Science Photo of the Week

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Offline Alandriel

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Spitzer telescope spies a stellar bubble blower
NASA/JPL NEWS RELEASE
Posted: November 14, 2007

A new image from NASA's Spitzer Space Telescope shows a baby star 1,140 light-years away from Earth blowing two massive "bubbles." But instead of bubble gum, this youngster, called HH 46/47, is using powerful jets of gas to make bubbles in outer space.



[attachment=1524]
In this processed Spitzer Space Telescope image, baby star HH 46/47 can be
 seen blowing two massive "bubbles." The star is 1,140 light-years away
from Earth. Credit: NASA/JPL-Caltech

Download larger image version here

 
 
The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are from starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. Red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

According to Thangasamy Velusamy of NASA's Jet Propulsion Laboratory in Pasadena, Calif., baby stars and their potential planet-forming disks grow by gravitationally pulling in and absorbing surrounding gas and dust. Scientists suspect that these disks stop growing when the central baby star develops powerful winds and jets that blow away surrounding material.

"Spitzer can image these jets and winds in infrared light and help us understand the details of these phenomena," says Velusamy.

For astronomers who know what to look for, Spitzer's supersensitive infrared instruments are excellent tools for studying young stars embedded within thick clouds of cosmic dust and gas, revealing information about their growth. However, Velusamy notes that it is often difficult for most people to get a clear, detailed picture of infant stars and their "growing pains."

"When you see a star through a telescope, its image is blurred in a known way, and the smaller the telescope the larger is the blurring," he says.

To clear up this blurring, astronomers at JPL developed an advanced image-processing technique for Spitzer data called Hi-Res deconvolution. This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When Velusamy and his team applied this technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

According to William Langer, also of JPL, this image will help scientists determine which of many different mechanisms are responsible for producing the winds and jets of baby stars.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

This paper on HH46/47 by Velusamy, Langer, and Kenneth Marsh, all of JPL, was published in the October issue of Astrophysical Journal Letters.

SOURCE: SPACELFIGHTNOW.ORG
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Rosetta: OSIRIS’ view of Earth by night
 
15 November 2007


This is a composite of four images combined to show the illuminated crescent of Earth and the cities of the northern hemisphere. The images were acquired with the OSIRIS Wide Angle Camera (WAC) during Rosetta’s second Earth swing-by on 13 November.

This image showing islands of light created by human habitation was taken with the OSIRIS WAC at 19:45 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80 000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth and Rosetta was about 160°). The image was taken with a five-second exposure of the WAC with the red filter.
[attachment=1575]
This image showing Earth’s illuminated crescent
 was taken with the WAC at 20:05 CET as Rosetta
 was about 75 000 km from Earth. The crescent
 seen is around Antarctica. The image is a colour
 composite combining images obtained at various wavelengths.


Credits: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA
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    Maunder Crater, perspective view
)





[attachment=1577]


Description
    The above image shows the striking Maunder crater located in the region of Noachis Terra on Mars. The crater lies at 50° South and 2° East. The High Resolution Stereo Camera (HRSC) on ESA’s Mars Express orbiter took pictures of the Noachis Terra region during orbits 2412 and 2467 on 29 November and 14 December 2005 respectively, with a ground resolution of approximately 15 metres per pixel.

    Named after the british astronomer Edward W. Maunder, the crater located halfway between Argyre Planitia and Hellas Planitia on the southern Highlands of Mars.

    This perspective view has been calculated from the digital terrain model derived from the HRSC stereo channels.

Credits:
    ESA/DLR/FU Berlin (G. Neuku
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Return To Europa: A Closer Look Is Possible
December 13, 2007

Jupiter’s moon Europa is just as far away as ever, but new research is bringing scientists closer to being able to explore its tantalizing ice-covered ocean and determine its potential for harboring life.

“We’ve learned a lot about Europa in the past few years,” says William McKinnon, professor of Earth and Planetary Sciences at Washington University in St. Louis, Mo.

“Before we were almost sure that there was an ocean, but now the scientific community has come to a consensus that there most certainly is an ocean. We’re ready to take the next step and explore that ocean and the ice shell that overlays it. We have a number of new discoveries and techniques that can help us do that.”

McKinnon is discussing some of these recent findings and new opportunities for exploring Europa in a news briefing today at the meeting of the American Geophysical Union in San Francisco. He is joined by colleagues Donald Blankenship, research scientist at the Institute for Geophysics at the University of Texas at Austin’s Jackson School of Geosciences., and Peter Doran, associate professor of Earth and Environmental Sciences, University of Illinois at Chicago.

McKinnon points to refined methods that can use combined measurements of gravity and the magnetic field made from orbit to characterize Europa's ocean. By observing how the moon flexes and deforms and by measuring magnetic variations, researchers can determine how thick or thin the ice is over the ocean and even learn how salty the ocean is. A new model shows that radiation on Europa is much less, up to two-thirds less, than previous models predicted, making the environment much more hospitable for orbiting spacecraft or landers to operate.

Sophisticated reprocessing of data from the Galileo mission has revealed new information about the chemistry of Europa’s surface. It maps the presence of carbon dioxide, an important chemical for life, most probably coming from the ocean beneath the surface. This indicates that improved measurements from orbit have the chance to detect compounds not found in the Galileo data.

Future explorations of Europa will benefit from lessons learned from the Cassini spacecraft’s recent findings of active geysers on Saturn’s moon Enceladus. “Europa is a young, geologically active body like Enceladus,” says McKinnon. Galileo didn’t see any plumes on Europa like those spouting from Enceladus, but it didn’t have the best instrumentation to detect the telltale hot spots. “Now we know what we should look for,” says McKinnon, “and we should expect the unexpected.”


[attachment=1788]

Thick or thin ice shell on Jupiter’s moon Europa? Scientists are all but certain that
 Europa has an ocean underneath its surface ice, but do not know how thick this ice might
 be. This artists’ conception illustrates two possible cut-away views through Europa’s ice
 shell. In both heat escapes, possibly volcanically, from Europa’s rocky mantle and is
carried upward by buoyant oceanic currents. If the heat from below is intense and the ice
 shell is thin enough (left), the ice shell can directly melt, causing what are called
“chaos” on Europa, regions of what appear to be broken, rotated, and tilted ice blocks. On
 the other hand, if the ice shell is sufficiently thick (right), the less intense interior
 heat will be transferred to the warmer ice at the bottom of the shell, and additional
heat is generated by tidal squeezing of the warmer ice. This warmer ice will slowly rise,
 flowing as glaciers do on Earth, and the slow but steady motion may also disrupt the
extremely cold, brittle ice at the surface. Europa is no larger than Earth’s moon, and its
 internal heating stems from its eccentric orbit about Jupiter, seen in the distance. As
tides raised by Jupiter in Europa’s ocean rise and fall, they may cause cracking,
additional heating, and even venting of water vapor into the airless sky above Europa’s
icy surface. (Artwork by Michael Carroll.) Credit: NASA/JPL.



New radar sounding techniques will be a key component for exploring Europa. “There have been theories about whether the ice above the ocean is thick or thin, and now we have the ability to determine this with radar,” says Blankenship. “That’s been proved by the radar on Mars Express, which imaged the north polar cap of Mars, and the higher-resolution radar on the Mars Reconnaissance Orbiter. Radar can give us a detailed cross section through the ice shell on Europa.” The ice-penetrating radar will also be able to locate liquid water both within and beneath the shell, he continues, just as it can spot water within crevasses and lakes beneath the ice of Antarctica. "Free water within the icy shell and its relationship to the underlying ocean will be a critical factor in determining the habitability of Europa."




Byrd Glacier, Antarctica. Analogs in Antarctica's ice-covered lakes will provide critical testing grounds for the technology needed to explore Europa's ice-covered ocean. More info>>Researchers are also preparing for the day in the future when they will be able to get to Europa's surface and ultimately into its ocean to explore it directly. "In the meantime, we're using extreme environments on Earth as our laboratory," says Doran. "Ice-covered lakes in Antarctica are good, small-scale analogs to what we might find on Europa." Doran is lead investigator of a project called Endurance, which, in collaboration with Stone Aerospace, is developing an autonomous underwater robotic vehicle, to test approaches and procedures for exploring Europa's ocean. The project is funded by NASA's Astrobiology Science and Technology for Exploring Planets program.

"We're testing the vehicle in Wisconsin in February 2008," Doran says, "and then we'll be deploying it in Antarctica later in the year." The robotic explorer will be able to create three-dimensional maps of the subsurface Antarctic lake. It will also be able to map the biochemistry of the water body, pinpointing the chemical signatures that may indicate life.

For Europa, under-ice exploration lies in the distant future. In the meantime, say the researchers, a closer look at Europa is possible from an orbiting spacecraft able to measure gravity and magnetic fields, determine surface composition, search for active or recent eruptions, and use radar to understand the relationship between the surface and the sub-surface.

SOURCE: JACKSON SCHOOL OF GEOSCIENCES
http://www.jsg.utexas.edu/news/releases.html

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'Death Star' galaxy black hole fires at neighbor
NASA NEWS RELEASE
Posted: December 17, 2007

WASHINGTON - A powerful jet from a super massive black hole is blasting a nearby galaxy, according to new findings from NASA observatories. This never-before witnessed galactic violence may have a profound effect on planets in the jet's path and trigger a burst of star formation in its destructive wake.

[attachment=1846]
This composite image shows the jet from a
black hole at the center of a galaxy striking
 the edge of another galaxy, the first time
such an interaction has been found. X-rays
from Chandra (colored purple), optical and
ultraviolet (UV) data from Hubble (red and
orange), and radio emission from the Very
Large Array (VLA) and MERLIN (blue) show
how the jet from the main galaxy on the
lower left is striking its companion galaxy
to the upper right.

 Credit: X-ray: NASA/CXC/CfA/D.Evans et al.; Optical/UV: NASA/STScI; Radio: NSF/VLA/CfA/D.Evans et al., STFC/JBO/MERLIN

 
 
Known as 3C321, the system contains two galaxies in orbit around each other. Data from NASA's Chandra X-ray Observatory show both galaxies contain super massive black holes at their centers, but the larger galaxy has a jet emanating from the vicinity of its black hole. The smaller galaxy apparently has swung into the path of this jet.

This "death star" galaxy was discovered through the combined efforts of both space and ground-based telescopes. NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope were part of the effort. The Very Large Array telescope, Socorro, N.M., and the Multi-Element Radio Linked Interferometer Network (MERLIN) telescopes in the United Kingdom also were needed for the finding.

"We've seen many jets produced by black holes, but this is the first time we've seen one punch into another galaxy like we're seeing here," said Dan Evans, a scientist at the Harvard-Smithsonian Center for Astrophysics and leader of the study. "This jet could be causing all sorts of problems for the smaller galaxy it is pummeling."

Jets from super massive black holes produce high amounts of radiation, especially high-energy X-rays and gamma-rays, which can be lethal in large quantities. The combined effects of this radiation and particles traveling at almost the speed of light could severely damage the atmospheres of planets lying in the path of the jet. For example, protective layers of ozone in the upper atmosphere of planets could be destroyed.

[attachment=1848]
An artist's illustration of the system,
 showing the main galaxy and the companion
 galaxy. A jet of particles generated by a
supermassive black hole at the center of the
 main galaxy is striking the companion galaxy.
 The jet is disrupted and deflected by this impact.
 The key features of this system are labeled in
the final view.

 Credit: NASA/CXC/M. Weiss

 
 
Jets produced by super massive black holes transport enormous amounts of energy far from black holes and enable them to affect matter on scales vastly larger than the size of the black hole. Learning more about jets is a key goal for astrophysical research.

"We see jets all over the universe, but we're still struggling to understand some of their basic properties," said co-investigator Martin Hardcastle of the University of Hertfordshire in the United Kingdom. "This system of 3C321 gives us a chance to learn how they're affected when they slam into something like a galaxy and what they do after that."

The effect of the jet on the companion galaxy is likely to be substantial, because the galaxies in 3C321 are extremely close at a distance of only about 20,000 light years apart. They lie approximately the same distance as Earth is from the center of the Milky Way galaxy.

A bright spot in the Very Large Array and MERLIN images shows where the jet has struck the side of the galaxy, dissipating some of the jet's energy. The collision disrupted and deflected the jet.

Another unique aspect of the discovery in 3C321 is how relatively short-lived this event is on a cosmic time scale. Features seen in the Very Large Array and Chandra images indicate that the jet began impacting the galaxy about one million years ago, a small fraction of the system's lifetime. This means such an alignment is quite rare in the nearby universe, making 3C321 an important opportunity to study such a phenomenon.

It is possible the event is not all bad news for the galaxy being struck by the jet. The massive influx of energy and radiation from the jet could induce the formation of large numbers of stars and planets after its initial wake of destruction is complete.

The results from Evans and his colleagues will appear in The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

SOURCE:SPACEFLIGHTNOW.ORG
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Far side of the Moon

[attachment=1975]
CREDIT:NASA


The far side of the Moon is the lunar hemisphere that is permanently turned away from the Earth. The far hemisphere was first photographed by the Soviet Luna 3 probe in 1959, and was first directly observed by human eyes when the Apollo 8 mission orbited the Moon in 1968. The rugged terrain is distinguished by a multitude of crater impacts, as well as relatively few lunar maria. It includes the largest known impact feature in the Solar System: the South Pole-Aitken basin. The far side has been suggested as a potential location for a large radio telescope, as it would be shielded from possible radio interference from Earth

SOURCE:Wikipedia

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It looks like the moon has taken quite a few blows for us. I, for one, will never swear at it again.
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Sunspot is harbinger of the new solar cycle
NOAA NEWS RELEASE
Posted: January 7, 2008

A new 11-year cycle of heightened solar activity, bringing with it increased risks for power grids, critical military, civilian and airline communications, GPS signals and even cell phones and ATM transactions, showed signs it was on its way last week when the cycle's first sunspot appeared in the sun's Northern Hemisphere, NOAA scientists said.



[attachment=2016]
First official sunspot belonging to the new Solar Cycle 24. Credit: NOAA
 

 
"This sunspot is like the first robin of spring," said solar physicist Douglas Biesecker of NOAA's Space Weather Prediction Center. "In this case, it's an early omen of solar storms that will gradually increase over the next few years."

A sunspot is an area of highly organized magnetic activity on the surface of the sun. The new 11-year cycle, called Solar Cycle 24, is expected to build gradually, with the number of sunspots and solar storms reaching a maximum by 2011 or 2012, though devastating storms can occur at any time.

During a solar storm, highly charged material ejected from the sun may head toward Earth, where it can bring down power grids, disrupt critical communications, and threaten astronauts with harmful radiation. Storms can also knock out commercial communications satellites and swamp Global Positioning System signals. Routine activities such as talking on a cell phone or getting money from an ATM machine could suddenly halt over a large part of the globe.

"Our growing dependence on highly sophisticated, space-based technologies means we are far more vulnerable to space weather today than in the past," said Vice Admiral Conrad C. Lautenbacher, Jr., under secretary of commerce for oceans and atmosphere and NOAA administrator. "NOAA's space weather monitoring and forecasts are critical for the nation's ability to function smoothly during solar disturbances."

Last April, in coordination with an international panel of solar experts, NOAA issued a forecast that Solar Cycle 24 would start in March 2008, plus or minus six months. The panel was evenly split between those predicting a strong or weak cycle. Both camps agree that the sooner the new cycle takes over the waning previous cycle, the more likely that it will be a strong season with many sunspots and major storms, said Biesecker. Many more sunspots with Solar Cycle 24 traits must emerge before scientists consider the new cycle dominant, with the potential for more frequent storms.

The new sunspot, identified as #10,981, is the latest visible spot to appear since NOAA began numbering them on January 5, 1972. Its high-latitude location at 27 degrees North, and its negative polarity leading to the right in the Northern Hemisphere are clear-cut signs of a new solar cycle, according to NOAA experts. The first active regions and sunspots of a new solar cycle can emerge at high latitudes while those from the previous cycle continue to form closer to the equator.

SWPC is the nation's first alert for solar activity and its affects on Earth. The center's space weather forecasters issue outlooks for the next 11-year solar "season" and warn of individual storms occurring on the sun that could impact Earth. SWPC is one of NOAA's nine National Centers for Environmental Prediction and is also the warning agency of the International Space Environment Service (ISES), a consortium of 11 member nations.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects


SOURCE: SPACEFLIGHTNOW.ORG
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Hot cyclones churn at both ends of Saturn
NASA/JPL NEWS RELEASE
Posted: January 5, 2008

Despite more than a decade of winter darkness, Saturn's north pole is home to an unexpected hot spot remarkably similar to one at the planet's sunny south pole. The source of its heat is a mystery. Now, the first detailed views of the gas giant's high latitudes from the Cassini spacecraft reveal a matched set of hot cyclonic vortices, one at each pole.



[attachment=2018]
This image shows newly discovered "hot spot"
 on Saturn's north pole and the mysterious
hexagon that encircles the pole.
 Credit: NASA/JPL/GSFC/Oxford University

 
 
While scientists already knew about the hot spot at Saturn's south pole from previous observations by the W. M. Keck Observatory in Hawaii, the north pole vortex was a surprise. The researchers report their findings in the Jan. 4 issue of Science.

"We had speculated that the south pole hot spot was connected to the southern, sunlit conditions," said Glenn Orton, a senior research scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and co-investigator on Cassini's composite infrared spectrometer. "Since the north pole has been deprived of sunlight since the arrival of winter in 1995, we didn't expect to find a similar feature there."

The infrared data show that the shadowed north pole vortex shares much the same structure and temperature as the one at the sunny south pole. The cores of both show a depletion of phospine gas, an imbalance probably caused by air moving downward into the lowest part of Saturn's atmosphere, the troposphere. Both polar vortices appear to be long-lasting and intrinsic parts of Saturn and are not related to the amount of sunlight received by one pole or the other.

"The hot spots are the result of air moving polewards, being compressed and heated up as it descends over the poles into the depths of Saturn," said Leigh Fletcher, a planetary scientist from the University of Oxford, England, and the lead author of the Science paper. "The driving forces behind the motion, and indeed the global motion of Saturn's atmosphere, still need to be understood."

Though similar, the two polar regions differ in one striking way. At the north pole, the newly discovered vortex is framed by the distinctive, long-lived and still unexplained polar hexagon. This mysterious feature encompassing the entire north pole was first spotted in the 1980s by NASA's Voyager 1 and 2 spacecraft. Cassini's infrared cameras also detected the hexagon in deep atmospheric clouds early in 2007.

In their paper, Fletcher and his colleagues report that the bright, warm hexagon is much higher than previous studies had shown. "It extends right to the top of the troposphere," says Fletcher. "It is associated with downward motion in the troposphere, though the cause of the hexagonal structure requires further study."

Winter lasts about 15 years on Saturn. Researchers anticipate that when the seasons change in the coming years and Saturn's north pole is once again in sunlight, they will be able to see a swirling vortex with high eye walls and dark central clouds like the one now visible at the south pole. "But Saturn may surprise us again," says Fletcher.

"The fact that Neptune shows a similar south polar hot spot whets our appetite for the strange dynamics of the poles of the other gas giants," Fletcher says.

More information about Jupiter's poles will come from NASA's Juno mission, currently scheduled for launch in 2011 and arrival in 2016.

Fletcher's research was funded by the United Kingdom's Science and Technology Facilities Council.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The science team for Cassini's composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md


SOURCE:SPACEFLIGHTNOW.ORG
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Even thin galaxies can grow fat black holes
NASA/JPL NEWS RELEASE
Posted: January 14, 2008

NASA's Spitzer Space Telescope has detected plump black holes where least expected -- skinny galaxies.

Like people, galaxies come in different shapes and sizes. There are thin spirals both with and without central bulges of stars, and more rotund ellipticals that are themselves like giant bulges. Scientists have long held that all galaxies except the slender, bulgeless spirals harbor supermassive black holes at their cores. Furthermore, bulges were thought to be required for black holes to grow.

[attachment=2201]


This artist's concept illustrates the two types
 of spiral galaxies that populate our universe:
 those with plump middles, or central bulges
(upper left), and those lacking the bulge
(foreground). Credit: NASA/JPL-Caltech

 
 
The new Spitzer observations throw this theory into question. The infrared telescope surveyed 32 flat and bulgeless galaxies and detected monstrous black holes lurking in the bellies of seven of them. The results imply that galaxy bulges are not necessary for black hole growth; instead, a mysterious invisible substance in galaxies called dark matter could play a role.

"This finding challenges the current paradigm. The fact that galaxies without bulges have black holes means that the bulges cannot be the determining factor, " said Shobita Satyapal of the George Mason University, Fairfax, Va. "It's possible that the dark matter that fills the halos around galaxies plays an important role in the early development of supermassive black holes."

Satyapal presented the findings at the 211th meeting of the American Astronomical Society in Austin, Texas. A study from Satyapal and her team will be published in the April 10 issue of the Astrophysical Journal.

Our own Milky Way is an example of a spiral galaxy with a bulge; from the side, it would look like a plane seen head-on, with its wings out to the side. Its black hole, though dormant and not actively "feeding," is several million times the mass of our sun.

Previous observations had suggested that bulges and black holes flourished together like symbiotic species. For instance, supermassive black holes are almost always about 0.2 percent the mass of their galaxies' bulges. In other words, the more massive the bulge, the more massive the black hole. Said Satyapal, "Scientists reasoned that somehow the formation and growth of galaxy bulges and their central black holes are intimately connected."

But a wrinkle appeared in this theory in 2003, when astronomers at the University of California, Berkeley, and Observatories of the Carnegie Institution of Washington, Pasadena, Calif., discovered a relatively "lightweight" supermassive black hole in a galaxy lacking a bulge. Then, earlier this year, Satyapal and her team uncovered a second supermassive black hole in a similarly svelte galaxy.

In the latest study, Satyapal and her colleagues report the discovery of six more hefty black holes in thin galaxies with minimal bulges, further weakening the "bulge-black hole" theory. Why hadn't anybody seen these black holes before? According to the scientists, bulgeless galaxies tend to be very dusty, letting little visible light escape. But infrared light can penetrate dust, so the team was able to use Spitzer's infrared spectrograph to reveal the "fingerprints" of active black holes lurking in galaxies millions of light years away.

"A feeding black hole spits out high-energy light that ionizes much of the gas in the core of the galaxy," said Satyapal. "In this case, Spitzer identified the unique fingerprint of highly ionized neon -- only a feeding black hole has the energy needed to excite neon to this state." The precise masses of the newfound black holes are unknown.

If bulges aren't necessary ingredients for baking up supermassive black holes, then perhaps dark matter is. Dark matter is the enigmatic substance that permeates galaxies and their surrounding halos, accounting for up to 90 percent of a galaxy's mass. So-called normal matter makes up stars, planets, living creatures and everything we see around us, whereas dark matter can't be seen. Only its gravitational effects can be felt. According to Satyapal, dark matter might somehow determine the mass of a black hole early on in the development of a galaxy.

"Maybe the bulge was just serving as a proxy for the dark matter mass -- the real determining factor behind the existence and mass of a black hole in a galaxy's center," said Satyapal.

Other authors of this study include: D. Vega of the George Mason University; R.P. Dudik of the George Mason University and NASA Goddard Space Flight Center, Greenbelt, Md.; N.P. Abel of the University of Cincinnati, Ohio; and Tim Heckman of the Johns Hopkins University, Baltimore, Md.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Jim Houck of Cornell.

SOURCE:SPACEFLIGHTNOW.COM
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The violent lives of galaxies: Caught in dark matter web
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: January 20, 2008





Astronomers are using NASA's Hubble Space Telescope to dissect one of the largest structures in the universe as part of a quest to understand the violent lives of galaxies. Hubble is providing indirect evidence of unseen dark matter tugging on galaxies in the crowded, rough-and-tumble environment of a massive supercluster of hundreds of galaxies.


[attachment=2203]





See larger image here
 
 
Dark matter is an invisible form of matter that accounts for most of the universe's mass. Hubble's Advanced Camera for Surveys has mapped the invisible dark matter scaffolding of the supercluster Abell 901/902, as well as the detailed structure of individual galaxies embedded in it.

The images are part of the Space Telescope Abell 901/902 Galaxy Evolution Survey (STAGES), which covers one of the largest patches of sky ever observed by the Hubble telescope. The area surveyed is so wide that it took 80 Hubble images to cover the entire STAGES field. The new work is led by Meghan Gray of the University of Nottingham in the United Kingdom and Catherine Heymans of the University of British Columbia in Vancouver, along with an international team of scientists.

The Hubble study pinpointed four main areas in the supercluster where dark matter has pooled into dense clumps, totaling 100 trillion times the Sun's mass. These areas match the location of hundreds of old galaxies that have experienced a violent history in their passage from the outskirts of the supercluster into these dense regions. These galaxies make up four separate galaxy clusters.

"Thanks to Hubble's Advanced Camera for Surveys, we are detecting for the first time the irregular clumps of dark matter in this supercluster," Heymans said. "We can even see an extension of the dark matter toward a very hot group of galaxies that are emitting X-rays as they fall into the densest cluster core."

The dark matter map was constructed by measuring the distorted shapes of over 60,000 faraway galaxies. To reach Earth, the galaxies' light traveled through the dark matter that surrounds the supercluster galaxies and was bent by the massive gravitational field. Heymans used the observed, subtle distortion of the galaxies' shapes to reconstruct the dark matter distribution in the supercluster using a method called weak gravitational lensing. The dark matter map is 2.5 times sharper than a previous ground-based survey of the supercluster.

"The new map of the underlying dark matter in the supercluster is one key piece of this puzzle," Gray explained. "At the same time we're looking in detail at the galaxies themselves." The survey's broader goal is to understand how galaxies are influenced by the environment in which they live.

On Earth, the pace of quiet country life is vastly different from the hustle of the big city. In the same way, galaxies living lonely isolated lives look very different from those found in the most crowded regions of the universe, like a supercluster. "We've known for a long time that galaxies in crowded environments tend to be older, redder, and rounder than those in the field," Gray said.

"Galaxies are continually drawn into larger and larger groups and clusters by the inevitable force of gravity as the universe evolves."

In such busy environments galaxies are subject to a life of violence: high-speed collisions with other galaxies; the stripping away of gas, the fuel supply they use to form new stars; and distortion due to the strong gravitational pull of the underlying invisible dark matter. "Any or all of these effects may play a role in the transformation of galaxies, which is what we're trying to determine," Gray said.

The STAGES survey's simultaneous focus on both the big picture and the details can be likened to studying a big city. "It's as if we're trying to learn everything we can about New York City and New Yorkers," Gray explained. "We're examining large-scale features, like mapping the roads, counting skyscrapers, monitoring traffic. At the same time we're also studying the residents to figure out how the lifestyles of people living downtown differ from those out in the suburbs. But in our case the city is a supercluster, the roads are dark matter, and the people are galaxies."

Further results by other team members support this view. "In the STAGES supercluster we clearly see that transformations are happening in the outskirts of the supercluster, where galaxies are still moving relatively slowly and first feel the influence of the cluster environment," said Christian Wolf, an Advanced Research Fellow at the University of Oxford in the U.K.

Assistant professor Shardha Jogee and graduate student Amanda Heiderman, both of the University of Texas in Austin, concur. "We see more collisions between galaxies in the regions toward which the galaxies are flowing than in the centers of the clusters," Jogee said. "By the time they reach the center, they are moving too fast to collide and merge, but in the outskirts their pace is more leisurely, and they still have time to interact."

The STAGES team also finds that the outer parts of the clusters are where star formation in the galaxies is slowly switching off and where the supermassive black holes at the hearts of the galaxies are most active.

Added Heiderman: "The galaxies at the centers of the clusters may have been there for a long time and have probably finished their transformation. They are now old, round, red, and dead."

The team plans more studies to understand how the supercluster environment is responsible for producing these changes.

Abell 901/902 resides 2.6 billion light-years from Earth and measures more than 16 million light-years across.

This work was supported by the Science and Technology Facilities Council (UK), NASA, the National Science Foundation Long Term Space Astrophysics (NASA LTSA) program, a Marie Curie Fellowship, a CITA National Fellowship, CIfAR, and CFI.


SOURCE:SPACEFLIGHTNOW.COM
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Circumstellar dust takes flight in 'The Moth'
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: January 20, 2008

What superficially resembles a giant moth floating in space is giving astronomers new insight into the formation and evolution of planetary systems.

This is not your typical flying insect. It has a wingspan of about 22 billion miles. The wing- like structure is actually a dust disk encircling the nearby, young star HD 61005, dubbed "The Moth." Its shape is produced by starlight scattering off dust.

[attachment=2205]


See larger image here
 
 
Dust disks around roughly 100-million-year-old stars like HD 61005 are typically flat, pancake-shaped structures where planets can form. But images taken with NASA's Hubble Space Telescope of "The Moth" are showing that some disks sport surprising shapes.

"It is completely unexpected to find a dust disk with this unusual shape," said senior research scientist Dean Hines of the Space Science Institute, New Mexico Office in Corrales, New Mexico, and a member of the Hubble team that discovered the disk. "We think HD 61005 is plowing through a local patch of higher-density gas in the interstellar medium, causing material within HD 61005's disk to be swept behind the star. What effect this might have on the disk, and any planets forming within it, is unknown."

Hines called this possible collision "unusual, because we don't expect very much interstellar material to be in the solar neighborhood. That's because the area through which our Sun is moving was evacuated within the past few million years by at least one supernova, the explosion of a massive star. Yet, here's evidence of dense material that's very close, only 100 light-years away."

Astronomers have found evidence that the environment in which a star forms influences its prospects for planet formation. Hubble has actually seen that young planet-forming disks can be affected directly by their environment. The harsh stellar radiation from the Trapezium stars in the Orion Nebula has altered some disks. It is unclear, however, what effect passage through a cloud similar to the one in which HD 61005 finds itself would have on planet formation. Researchers have speculated that passage through dense regions of the interstellar medium could impact the atmospheres of evolving planets.

The Moth is part of a survey of Sun-like stars that Hines and collaborators observed with Hubble's Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) and NASA's Spitzer Space Telescope to study the formation and evolution of planetary systems. Under the lead of Michael Meyer of the University of Arizona in Tucson, the team initially used Spitzer to look for heat radiation‹the tell-tale sign of dust warmed by the star‹to identify interesting star systems.

Hines then teamed with Glenn Schneider of the University of Arizona to use Hubble's high- contrast imaging capability of the NICMOS coronagraph to image these disks and reveal where the dust detected by Spitzer resides. The NICMOS coronagraph blocked out the starlight so that astronomers could see details in the surrounding disk.

"These symbiotic capabilities, uniquely implemented in NASA's Great Observatories, provide astronomers with the powerful observational tools to study the circumstellar environments of potentially planet-forming systems," Schneider said.

Added Meyer: "Combining observations from these two spacecraft gives us information about the composition of the dust grains, whether they're icy or sandy, or whether they're like the sooty smoke particles rising from a chimney. The composition and sizes of the dust can tell us a lot about the dynamics and evolution of a solar system. In our solar system, for example, astronomers have evidence of rocks smashing into each other and generating dust, as in the asteroid and Kuiper belts. We're seeing these same processes unfold in other planetary systems


SOURCE:SPACEFLIGHTNOW.COM
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Unusual supernovae may reveal black holes
UC-SANTA CRUZ NEWS RELEASE
Posted: January 29, 2008

A strange and violent fate awaits a white dwarf star that wanders too close to a moderately massive black hole. According to a new study, the black hole's gravitational pull on the white dwarf would cause tidal forces sufficient to disrupt the stellar remnant and reignite nuclear burning in it, giving rise to a supernova explosion with an unusual appearance. Observations of such supernovae could confirm the existence of intermediate-mass black holes, currently the subject of much debate among astronomers.

[attachment=2297]
This series of images shows the interaction of a white dwarf
star with a black hole. As it passes the black hole, the white
 dwarf becomes strongly compressed and heated (top left),
triggering an explosion. Most of the stellar mass is ejected
 into space (the "bubble" in the upper right part of the debris
 in the top right image), while the rest (the cusp-like part
of the image) falls toward the black hole. While the ejected
matter expands rapidly, the infalling matter builds a violent,
thick accretion disk around the black hole.

 
 
"Our supercomputer simulations show a peculiar supernova that would be a unique signature of an intermediate-mass black hole," said Enrico Ramirez-Ruiz, assistant professor of astronomy and astrophysics at the University of California, Santa Cruz.

Ramirez-Ruiz and his collaborators--Stephan Rosswog of Jacobs University in Bremen, Germany, and William Hix of Oak Ridge National Laboratory--used detailed computer simulations to follow the entire process of tidal disruption of a white dwarf by a black hole. Their simulations included gas dynamics, gravity, and nuclear physics, requiring weeks of computer time to simulate events that would take place in a fraction of a second. A paper describing their results has been accepted for publication in Astrophysical Journal Letters, and a preprint is currently available online.

"Every star that is not too massive ends up as a white dwarf, so they are very common. We were interested in whether tidal disruption can bring this stellar corpse to life again," said Rosswog, the first author of the paper.

A white dwarf can explode as a "type Ia" supernova if it accumulates enough mass by siphoning matter away from a companion star. When it reaches a critical mass (about 1.4 times the mass of the Sun), the white dwarf collapses and explodes. Astronomers use these type Ia supernovae as "standard candles" for cosmic distance measurements because their brightness evolves over time in a predictable manner.

The new paper describes a distinctly different mechanism for igniting a white dwarf, in which tidal disruption by a black hole causes drastic compression of the stellar material. The white dwarf is flattened into a pancake shape aligned in the plane of its orbit around the black hole. As each section of the star is squeezed through a point of maximum compression, the extreme pressure causes a sharp increase in temperatures, which triggers explosive burning.

The explosion ejects more than half of the debris from the disrupted star, while the rest of the stellar material falls into the black hole. The infalling material forms a luminous accretion disk that emits x-rays and should be detectable by the Chandra X-ray Observatory, the researchers said.

"This is a new mechanism for ignition of a white dwarf that results in a very different type of supernova than the standard type Ia, and it is followed by an x-ray source," Ramirez-Ruiz said.

He estimated that this type of event would occur about 100 times less frequently than the standard type Ia supernovae, but should be detectable by future surveys designed to observe large numbers of supernovae. The Large Synoptic Survey Telescope (LSST), planned for completion in 2013, is expected to discover hundreds of thousands of type Ia supernovae per year.

"These exotic creatures will start showing up in the data from the LSST," Ramirez-Ruiz said. "We want to predict the light curves so we can look for them in the survey data."

The mechanism described in the paper requires a black hole that is neither too small nor too big. Such intermediate-mass black holes (500 to 1,000 times the mass of the Sun) may reside in some globular star clusters, but there is much less evidence for their existence than there is for the relatively small stellar black holes (tens of times the mass of the Sun) or for supermassive black holes (a few million times the mass of the Sun), found at the centers of galaxies.

The new paper describes in detail the disruption of a white dwarf with two-tenths the mass of the Sun by a black hole 1,000 times the mass of the Sun. The researchers also found that they can vary the mass of the white dwarf and still get the same outcome--tidal disruption and ignition of the white dwarf.

"We can ignite the whole mass range of white dwarfs if they get close enough to the black hole," Rosswog said.

This research was supported by the Department of Energy's Program for Scientific Discovery through Advanced Computing


SOURCE:SPACEFLIGHTNOW.COM
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Spacecraft photographs avalanches on Mars
NASA/JPL NEWS RELEASE


PASADENA, Calif. - A NASA spacecraft in orbit around Mars has taken the first ever image of active avalanches near the Red Planet's north pole. The image shows tan clouds billowing away from the foot of a towering slope, where ice and dust have just cascaded down.

[attachment=2504]


Credit: NASA/JPL-Caltech/University of Arizona
[biggy piccy HERE

 
 
The High Resolution Imaging Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter took the photograph Feb. 19. It is one of approximately 2,400 HiRISE images being released today.

Ingrid Daubar Spitale of the University of Arizona, Tucson, who works on targeting the camera and has studied hundreds of HiRISE images, was the first person to notice the avalanches. "It really surprised me," she said. "It's great to see something so dynamic on Mars. A lot of what we see there hasn't changed for millions of years."

The camera is looking repeatedly at selected places on Mars to track seasonal changes. However, the main target of the Feb. 19 image was not the steep slope.

"We were checking for springtime changes in the carbon-dioxide frost covering a dune field, and finding the avalanches was completely serendipitous," said Candice Hansen, deputy principal investigator for HiRISE, at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The full image reveals features as small as a desk in a strip of terrain 6 kilometers (3.7 miles) wide and more than 10 times that long, at 84 degrees north latitude. Reddish layers known to be rich in water ice make up the face of a steep slope more than 700 meters (2,300 feet) tall, running the length of the image.

"We don't know what set off these landslides," said Patrick Russell of the University of Berne, Switzerland, a HiRISE team collaborator. "We plan to take more images of the site through the changing Martian seasons to see if this kind of avalanche happens all year or is restricted to early spring."

More ice than dust probably makes up the material that fell from the upper portion of the scarp. Imaging of the site during coming months will track any changes in the new deposit at the base of the slope. That will help researchers estimate what proportion is ice.

"If blocks of ice broke loose and fell, we expect the water in them will be changing from solid to gas," Russell said. "We'll be watching to see if blocks and other debris shrink in size. What we learn could give us a better understanding of one part of the water cycle on Mars."



SOURCE: SPACEFLIGHNOW.ORG
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It looks like a glacial flow sort of thing, and there is a big drop at the edge.
Beeswax: Natures petrol tank sealant.

When things are in 3D, is it always the same three dimensions?

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SNR 0509-67.5:
Action Replay Of Powerful Stellar Explosion


[attachment=2542]
SNR 0509-67.5
Credit: X-ray: NASA/CXC/Rutgers/J.Warren, J.Hughes; Optical (Light Echo): NOAO/AURA/NSF/Harvard/A.Rest et al.; Optical (LMC): NOAO/AURA/NSF/S.Points, C.Smith & MCELS team

Bigger PICCY HERE

This combination of X-ray and optical images shows the aftermath of a powerful supernova explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light years from Earth. The debris from this explosion, the supernova remnant SNR 0509-67.5, is shown in a Chandra X-ray Observatory image (upper inset), where the lowest energy X-rays are shown in red, the intermediate energies are green and the highest energies are blue. In 2004, scientists used Chandra to show that SNR 0509-67.5 was likely caused by a Type Ia supernova, using an analysis of the elements, such as silicon and iron, that were detected. A Type Ia is thought to result from a white dwarf star in a binary system that reaches a critical mass and explodes.


The light echo image , from the National Science Foundation's Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, shows optical light from the original supernova explosion that has bounced off dust clouds in the neighboring regions of the LMC (the light echoes are shown in blue and stars in orange). The light from these echoes travels a longer path than the light that travels straight toward us, and so can be seen hundreds of years after the supernova itself. This image is one of a sequence of 5 images taken between 2001 and 2006 that are shown separately in a time-lapse movie.


The large optical image is from the Magellanic Cloud Emission Line Survey (MCELS), obtained with the University of Michigan's 0.9-meter Curtis Schmidt telescope at CTIO. Emission lines of hydrogen (H-alpha) are red, singly-ionized sulfur is green and doubly-ionized oxygen is blue. The image highlights regions of star formation in the LMC, including supernova remnants and giant structures carved out by multiple supernovas.

For the first time astronomers have used two methods - X-ray observations of a supernova remnant and optical observations of the expanding light echoes from the explosion - to estimate the energy of a supernova explosion. In two separate papers, astronomers concluded that the supernova occurred about 400 years ago (in Earth's time frame), and was unusually bright and energetic. This is the best ever determination of the power of a supernova explosion long after it was visible from Earth.

In the new optical study spectra of the light echo, obtained with Gemini Observatory, were used to confirm that the supernova was a Type Ia and to unambiguously determine the particular class of explosion and therefore its energy. In the new X-ray study, spectra from Chandra and ESA's XMM-Newton Observatory were then independently used to calculate the amount of energy involved in the original explosion, using an analysis of the supernova remnant and state-of-the-art explosion models. The X-ray work also concluded that the explosion was an especially energetic and bright variety of Type Ia supernova, confirming the validity of the explosion models.


SOURCE:chandra.harvard.edu
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Molecular Cloud Barnard 68

[attachment=2560]
Credit: FORS Team, 8.2-meter VLT Antu, ESO

Explanation: Where did all the stars go? What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gas absorb practically all the visible light emitted from background stars. The eerily dark surroundings help make the interiors of molecular clouds some of the coldest and most isolated places in the universe. One of the most notable of these dark absorption nebulae is a cloud toward the constellation Ophiuchus known as Barnard 68, pictured above. That no stars are visible in the center indicates that Barnard 68 is relatively nearby, with measurements placing it about 500 light-years away and half a light-year across. It is not known exactly how molecular clouds like Barnard 68 form, but it is known that these clouds are themselves likely places for new stars to form. It is possible to look right through the cloud in infrared light.

SOURCE:http://antwrp.gsfc.nasa.gov/apod/ap080323.html
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Thanks Neil [:)] I like that picture :)

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Thanks Neil [:)] I like that picture :)

You're welcome chum...here's a link to big version http://antwrp.gsfc.nasa.gov/apod/image/0803/barnard68_vlt_big.jpg
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Across the Universe


 How far can you see? Even the faintest stars visible to the eye are merely hundreds or thousands of light-years distant, all well within our own Milky Way Galaxy. Of course, if you know where to look you can also spot the Andromeda Galaxy as a pale, fuzzy cloud, around 2.5 million light-years away. But staring toward the northern constellation Bootes on March 19th, even without binoculars or telescope you still could have witnessed a faint, brief, flash of light from a gamma-ray burst. The source of that burst has been discovered to lie over halfway across the Universe at a distance of about 7.5 billion light-years. Now holding the distinction of the most distant object that could be seen by the unaided eye and the intrinsically brightest object ever detected, the cosmic explosion is estimated to have been over 2.5 million times more luminous than the brightest known supernova. The monster burst was identified and located by the orbiting Swift satellite, enabling rapid distance measurements and follow-up observations by large ground-based telescopes.



[attachment=2606]

 The fading afterglow of the gamma-ray burster, cataloged as GRB080319B, is shown in these two panels in X-rays (left) and ultraviolet light (right).


Credit: NASA Swift Team, Stefan Immler (GSFC) et al


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The N44 Complex


 A truly giant complex of emission nebulae, N44 is about 1,000 light-years across. It shines in southern skies as a denizen of our neighboring galaxy, the Large Magellanic Cloud, 170,000 light-years away. Winds and intense radiation from hot, young, luminous stars in N44 excite and sculpt filaments and streamers of the glowing nebular gas. But supernovae - the death explosions of the massive short lived stars - have also likely contributed to the region's enormous, blown-out shapes. The cluster of young stars seen near the center lies in a superbubble nearly 250 light-years across. This detailed, false-color view of the intricate structures codes emission from hydrogen, oxygen, and sulfur in shades of blue and green.


[attachment=2608]




Credit & Copyright: Don Goldman, Macedon Ranges Observatory
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Galaxy Wars: M81 versus M82

 On the left, surrounded by blue spiral arms, is spiral galaxy M81. On the right marked by red gas and dust clouds, is irregular galaxy M82. This stunning vista shows these two mammoth galaxies locked in gravitational combat, as they have been for the past billion years. The gravity from each galaxy dramatically affects the other during each hundred million-year pass. Last go-round, M82's gravity likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms. But M81 left M82 with violent star forming regions and colliding gas clouds so energetic the galaxy glows in X-rays. In a few billion years only one galaxy will remain.



[attachment=2610]


 Credit: Rainer Zmaritsch & Alexander Gross
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Embryonic planet imaged around young star
BY EMILY BALDWIN
ASTRONOMY NOW
Posted: April 2, 2008



[attachment=2638]


This is an image from
 the computer simulation of HL Tau and its
surrounding disc. In the model the dense clump
 (seen here at top right) forms with a mass
of about 8 times that of Jupiter at a distance
 from the star about 75 times that from the
Earth to the Sun. Image: Greaves, Richards,
 Rice & Muxlow 2008
).


The youngest planet ever to be seen has been captured in its earliest stage of formation in a disc of gas and rocky debris around a star 520 light years away.

Using the MERLIN and Very Large Array radio observatories in the UK and US respectively, a team of astronomers lead by Dr Jane Greaves of the University of St Andrews studied the disc of gas and rocky particles surrounding the extremely young star HL Tau and identified a 'clump' of material at a distance of about 65 AU from the parent star, twice as far from HL Tau as Neptune is from our Sun.

 
 
"This star is probably less than 100,000 years old," says Greaves, "and we see a distinct ball of gas and dust orbiting around it, which is exactly how a protoplanet should look." The protoplanet is made up of dust grains and fist-sized rocks, and could form a planet about 14 times as massive as Jupiter.

Using computer simulations, team member Dr Ken Rice of the University of Edinburgh showed that a massive protoplanet of around 8 Jupiter masses could condense out of a disc into a self-constrained structure at a distance comparable to that observed by the radio telescopes. "The simulations show that the gravitational instability model really does work," comments Greaves. "This is the first image of a protoplanet that has ever been made and we've also captured the environment in which the planet is forming."

The team hope to use the eMERLIN telescope array to make similar observations of other protoplanetary discs, which may be able to resolve Earth-sized exoplanets.

SOURCE:SPACEFLIGHTNOW.ORG
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South of Orion
Credit & Copyright: Johannes Schedler (Panther Observatory)


[attachment=2651]

BIGGY PICCY

This tantalizing array of nebulae and stars can be found about 2 degrees south of the famous star-forming Orion Nebula. The region abounds with energetic young stars producing jets and outflows that push through the surrounding material at speeds of hundreds of kilometers per second. The interaction creates luminous shock waves known as Herbig-Haro (HH) objects. For example, the graceful, flowing arc just right of center is cataloged as HH 222, also called the Waterfall Nebula. Seen below the Waterfall, HH 401 has a distinctive cone shape. The bright bluish nebula below and left of center is NGC 1999, a dusty cloud reflecting light from an embedded variable star. The entire cosmic vista spans over 30 light-years, near the edge of the Orion molecular cloud complex some 1,500 light-years distant.

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'Focused' solar explosions get millions of degrees hotter
NASA-GODDARD NEWS RELEASE


A NASA-funded researcher has discovered that solar flares -- explosions in the atmosphere of the sun -- get much hotter when they stay "focused".

"A flare typically divides its energy between directly heating the solar atmosphere and accelerating particles," said Dr. Ryan Milligan of the Oak Ridge Association of Universities, Tennessee, who is stationed at NASA's Goddard Space Flight Center in Greenbelt, Md. "This flare seemed to focus on one task, devoting all its energy to heating, allowing it to become millions of degrees hotter than its multi-tasking cousins." The result was presented at the Royal Astronomical Society's National Astronomy Meeting 2008 at Queen's University, Belfast, United Kingdom.

[attachment=2756]
An image of the solar flare taken using the X-Ray
 Telescope onboard Hinode on June 7, 2007. This
shows the flare loops in the solar atmopshere
at temperatures exceeding 10 million degree Celsius. Credit: JAXA

 
 
Solar flares are caused by the sudden release of magnetic energy. The largest can release as much energy as a billion one-megaton nuclear bombs. However, the flare observed in this study was a less powerful "micro" flare. NASA researchers want to understand flares because they generate radiation that can be hazardous to unprotected astronauts, like those walking on the surface of the moon.

Flares normally occur above loops of electrically conducting gas, called plasma, in the sun's atmosphere. When a typical flare goes off, it heats the plasma and sends beams of electrons racing down the sides of the loops. The electron beams evaporate more plasma from the sun's visible surface, which expands back up the loops.

"This evaporated plasma has traditionally been believed to be the source of the hottest temperatures seen in solar flares," said Milligan. "However, the flare in this new observation reached a temperature of almost 27 million degrees Fahrenheit -- some nine million degrees hotter than expected for a flare of this size -- without any evidence for beams of accelerated electrons."

Milligan used the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Hinode spacecraft to make his observation of the microflare on June 7, 2007. RHESSI revealed that the flare had a peak temperature of 27 million degrees, and also that the flare showed no evidence for high-energy electrons. Hinode was able to show the effects of the energy released at various layers in the solar atmosphere. In particular, the Extreme-ultraviolet Imaging Spectrometer instrument was used to detect signatures of plasma evaporation from the sun's surface through Doppler shifts of emission lines. The low-velocities observed confirmed the RHESSI observation that high-energy electrons were not present.

"If our assumption is correct, then this result tells us that the energy released during a solar flare is more efficient at achieving a higher temperature if the energy is used to directly heat the plasma in the sun's atmosphere, instead of being divided between heating and particle acceleration. This very effect has recently been shown in computer simulations of energy release during microflares," said Milligan.

The research was funded by the NASA Postdoctoral Program administered by the Oak Ridge Association of Universities, Tennessee.

Hinode is a Japanese mission, collaborating with NASA and the Science and Technology Facilities Council, United Kingdom, as international partners. The RHESSI project is a NASA Small Explorer mission managed by the Space Sciences Laboratory of the University of California, Berkeley. The Explorers Program Office at Goddard provides management and technical oversight under the direction of the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington, D.C

SOURCE: SPACEFLIGHTNEWS.COM
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Black hole found in center of enigmatic Omega Centauri
HUBBLE EUROPEAN SPACE AGENCY INFORMATION CENTRE RELEASE

Omega Centauri has been known as an unusual globular cluster for a long time. A new result obtained by the NASA/ESA Hubble Space Telescope and the Gemini Observatory reveals that the explanation behind Omega Centauri's peculiarities may be a black hole hidden in its center. One implication of the discovery is that it is very likely that Omega Centauri is not a globular cluster at all, but a dwarf galaxy stripped of its outer stars, as some scientists have suspected for a few years.

[attachment=2758]
Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
 
 
A new discovery has resolved some of the mystery surrounding Omega Centauri, the largest and brightest globular cluster in the sky. Images obtained with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope and data obtained by the GMOS spectrograph on the Gemini South telescope in Chile show that Omega Centauri appears to harbour an elusive intermediate-mass black hole in its center.

"This result shows that there is a continuous range of masses for black holes, from supermassive, to intermediate-mass, to small stellar mass types," explained astronomer Eva Noyola of the Max-Planck Institute for Extraterrestrial Physics in Garching, Germany, and leader of the team that made the discovery.

Omega Centauri is visible from Earth with the naked eye and is one of the favourite celestial objects for stargazers from the southern hemisphere. Although the cluster is 17 000 light-years away, located just above the plane of the Milky Way, it appears almost as large as the full Moon when the cluster is seen from a dark rural area. Exactly how Omega Centauri should be classified has always been a contentious topic.

It was first listed in Ptolemy's catalogue nearly two thousand years ago as a single star. Edmond Halley reported it as a nebula in 1677. In the 1830s the English astronomer John Herschel was the first to recognise it as a globular cluster. Now, more than a century later, this new result suggests Omega Centauri is not a globular cluster at all, but a dwarf galaxy stripped of its outer stars.

Globular clusters consist of up to one million old stars tightly bound by gravity and are found in the outskirts of many galaxies including our own. Omega Centauri has several characteristics that distinguish it from other globular clusters: it rotates faster than a run-of-the-mill globular cluster, its shape is highly flattened and it consists of several generations of stars - more typical globulars usually consist of just one generation of old stars.

Moreover, Omega Centauri is about 10 times as massive as other big globular clusters, almost as massive as a small galaxy. These peculiarities have led astronomers to suggest that Omega Centauri may not be a globular cluster at all, but a dwarf galaxy stripped of its outer stars by an earlier encounter with the Milky Way.

"Finding a black hole at the heart of Omega Centauri could have profound implications for our understanding of its past interaction with the Milky Way," said Noyola.

Eva Noyola and her colleagues measured the motions and brightnesses of the stars at the center of Omega Centauri. The measured velocities of the stars in the center are related to the total mass of the cluster and were far higher than expected from the mass deduced from the number and type of stars seen. So, there had to be something extraordinarily massive (and invisible) at the center of the cluster responsible for the fast-swirling dance of stars ‹ almost certainly a black hole with a mass of 40 000 solar masses.

"Before this observation, we had only one example of an intermediate-mass black hole ‹ in the globular cluster G1, in the nearby Andromeda Galaxy," said astronomer Karl Gebhardt of the University of Texas at Austin, USA, and a member of the team that made the discovery.

Although the presence of an intermediate-mass black hole is the most likely reason for the stellar speedway near the cluster's center, astronomers have analysed a couple of other possible causes: a collection of unseen burnt-out stars such as white dwarfs or neutron stars adding extra mass, or a group of stars with elongated orbits that would make the stars closest to the center appear to speed up.

According to Noyola these alternative scenarios are unlikely: "The normal evolution of a star cluster like Omega Centauri should not end up with stars behaving in those ways. Even if we assume that either scenario did happen somehow, both configurations are expected to be very short-lived. A clump of burnt-out stars, for example, is expected to move farther away from the cluster center quickly. For stars with elongated orbits, these orbits are expected to become circular very quickly."

According to scientists, these intermediate-mass black holes could turn out to be "baby" supermassive black holes. "We may be on the verge of uncovering one possible mechanism for the formation of supermassive black holes. Intermediate-mass black holes like this could be the seeds of full-sized supermassive black holes." Astronomers have debated the existence of intermediate-mass black holes because they have not found strong evidence for them and there is no widely accepted mechanism for how they could form. They have ample evidence that small black holes of a few solar masses are produced when giant stars die. There is similar evidence that supermassive black holes weighing the equivalent of millions to billions of solar masses sit at the heart of many galaxies, including our own Milky Way.

Intermediate-mass black holes may be rare and exist only in former dwarf galaxies that have been stripped of their outer stars, but they could also be more common than expected, existing at the centers of globular clusters as well. A previous Hubble survey of supermassive black holes and their host galaxies showed a correlation between the mass of a black hole and that of its host. Astronomers estimate that the mass of the dwarf galaxy that may have been the precursor of Omega Centauri was roughly 10 million solar masses. If lower mass galaxies obey the same rule as more massive galaxies that host supermassive black holes, then the mass of Omega Centauri does match that of its black hole.

The team will use the European Southern Observatory's Very Large Telescope in Paranal, Chile to conduct follow-up observations of the velocity of the stars near the cluster's center to confirm the discovery.


SOURCE: SPACEFLIGHTNOW.COM
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Stellar birth observed in the galactic wilderness
NASA/JPL NEWS RELEASE


A new image from NASA's Galaxy Evolution Explorer shows baby stars sprouting in the backwoods of a galaxy -- a relatively desolate region of space more than 100,000 light-years from the galaxy's bustling center.

[attachment=2778]




The blue and pink pinwheel in the center is the
 Southern pinwheel galaxy's main stellar disk,
 while the flapping, ribbon-like structures are
its extended arms. Image credit:
 NASA/JPL-Caltech/VLA/MPIA

 
 
The striking image, a composite of ultraviolet data from the Galaxy Evolution Explorer and radio data from the National Science Foundation's Very Large Array in New Mexico, shows the Southern Pinwheel galaxy, also known simply as M83.

In the new view, the main spiral, or stellar, disk of M83 looks like a pink and blue pinwheel, while its outer arms appear to flap away from the galaxy like giant red streamers. It is within these so-called extended galaxy arms that, to the surprise of astronomers, new stars are forming.

"It is absolutely stunning that we find such an enormous number of young stars up to 140,000 light-years away from the center of M83," said Frank Bigiel of the Max Planck Institute for Astronomy in Germany, lead investigator of the new Galaxy Evolution Explorer observations. For comparison, the diameter of M83 is only 40,000 light-years across.

Some of the "outback" stars in M83's extended arms were first spotted by the Galaxy Evolution Explorer in 2005. Remote stars were also discovered around other galaxies by the ultraviolet telescope over subsequent years. This came as a surprise to astronomers because the outlying regions of a galaxy are assumed to be relatively barren and lack high concentrations of the ingredients needed for stars to form.

The newest Galaxy Evolution Explorer observations of M83 (colored blue and green) were taken over a longer period of time and reveal many more young clusters of stars at the farthest reaches of the galaxy. To better understand how stars could form in such unexpected territory, Bigiel and his colleagues turned to radio observations from the Very Large Array (red). Light emitted in the radio portion of the electromagnetic spectrum can be used to locate gaseous hydrogen atoms, or raw ingredients of stars. When the astronomers combined the radio and Galaxy Evolution Explorer data, they were delighted to see they matched up.

"The degree to which the ultraviolet emission and therefore the distribution of young stars follows the distribution of the atomic hydrogen gas out to the largest distances is absolutely remarkable," said Fabian Walter, also of the Max Planck Institute for Astronomy, who led the radio observations of hydrogen in the galaxy.

The astronomers speculate that the young stars seen far out in M83 could have formed under conditions resembling those of the early universe, a time when space was not yet enriched with dust and heavier elements.

"Even with today's most powerful telescopes, it is extremely difficult to study the first generation of star formation. These new observations provide a unique opportunity to study how early generation stars might have formed," said co-investigator Mark Seibert of the Observatories of the Carnegie Institution of Washington in Pasadena.

M83 is located 15 million light-years away in the southern constellation Hydra.


SOURCE: SPACEFLIGHTNEWS.COM

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ABOVE THE CLOUDS

[attachment=2821]




From the windswept peak of Mauna Kea, on the Big Island of Hawaii, your view of the world at night could look like this. At an altitude of about 13,500 feet, the mountain top is silhouetted in the stunning skyscape recorded near dusk in early December of 2005. The volcanic peak rises just above a sea of storm clouds illuminated by a bright Moon. Planet Venus is setting near the Moon as the brilliant evening star. The scene also includes the faint, milky band of our own galaxy's disk of stars and cosmic dust clouds stretching from the horizon into the sky along the right edge of the frame.

SOURCE:http://antwrp.gsfc.nasa.gov
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Neil I think that your Hawaiian (sp) picture is fantastic !!!!!!!!!
Rosalind Franklin was my first cousin and one my life's main regrets is that I never met this brilliant and beautiful lady.
She discovered the Single DNA Helix in 1953, then it was taken by Wilkins without her knowledge or agreeement.

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Hurricane Florence was photographed by the crew on board the Space Shuttle Atlantis in November 1994. The hurricane is located over the Atlantic Ocean about 600 km from the coast of Bermuda. The image shows the typical pattern of hurricane systems: a large-scale line of clouds spiralling from bottom centre towards the central and thicker part of the storm, with the small clear "eye" at its very centre.
Source:sciencephotogallery.co.uk
« Last Edit: 19/05/2009 21:52:31 by BenV »

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Neil I think that your Hawaiian (sp) picture is fantastic !!!!!!!!!

Glad you like it Rosalind !..it is rather spectacular isn't it ?
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NASA spacecraft tracks raging Saturn storm
NASA/JPL NEWS RELEASE
Posted: April 29, 2008

PASADENA, Calif. -- As a powerful electrical storm rages on Saturn with lightning bolts 10,000 times more powerful than those found on Earth, the Cassini spacecraft continues its five-month watch over the dramatic events.



[attachment=2899]


The view at left was created by combining images
taken using red, green and blue spectral filters,
 and shows Saturn in colors that approximate what
 the human eye would see. The storm stands out
with greater clarity in the sharpened, enhanced
color view at right.
 Credit: NASA/JPL/Space Science Institute

 
 See a larger image here


Scientists with NASA's Cassini-Huygens mission have been tracking the visibly bright, lightning-generating storm -- the longest continually observed electrical storm ever monitored by Cassini.

Saturn's electrical storms resemble terrestrial thunderstorms, but on a much larger scale. Storms on Saturn have diameters of several thousand kilometers (thousands of miles), and radio signals produced by their lightning are thousands of times more powerful than those produced by terrestrial thunderstorms.

Lightning flashes within the persistent storm produce radio waves called Saturn electrostatic discharges, which the radio and plasma wave science instrument first detected on Nov. 27, 2007. Cassini's imaging cameras monitored the position and appearance of the storm, first spotting it about a week later, on Dec. 6.

"The electrostatic radio outbursts have waxed and waned in intensity for five months now," said Georg Fischer, an associate with the radio and plasma wave science team at the University of Iowa, Iowa City. "We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn."

The new storm is located in Saturn's southern hemisphere -- in a region nicknamed "Storm Alley" by mission scientists -- where the previous lightning storms were observed by Cassini.

"In order to see the storm, the imaging cameras have to be looking at the right place at the right time, and whenever our cameras see the storm, the radio outbursts are there," said Ulyana Dyudina, an associate of the Cassini imaging team at the California Institute of Technology in Pasadena, Calif.

Cassini's radio plasma wave instrument detects the storm every time it rotates into view, which happens every 10 hours and 40 minutes, the approximate length of a Saturn day. Every few seconds the storm gives off a radio pulse lasting for about a tenth of a second, which is typical of lightning bolts and other electrical discharges. These radio waves are detected even when the storm is over the horizon as viewed from Cassini, a result of the bending of radio waves by the planet's atmosphere.

Amateur astronomers have kept track of the storm over its five-month lifetime. "Since Cassini's camera cannot track the storm every day, the amateur data are invaluable," said Fischer. "I am in continuous contact with astronomers from around the world."

The long-lived storm will likely provide information on the processes powering Saturn's intense lightning activity. Cassini scientists will continue to monitor Storm Alley as the seasons change, bringing the onset of autumn to the planet's southern hemisphere.

SOURCE: SPACELIGHTNOW.COM

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Compact galaxies in early universe pack a big punch
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: April 29, 2008


Imagine receiving an announcement touting the birth of a baby 20 inches long and weighing 180 pounds. After reading this puzzling message, you would immediately think the baby's weight was a misprint.

Astronomers looking at galaxies in the universe's distant past received a similar perplexing announcement when they found nine young, compact galaxies, each weighing in at 200 billion times the mass of the Sun. The galaxies, each only 5,000 light-years across, are a fraction of the size of today's grownup galaxies but contain approximately the same number of stars. Each galaxy could fit inside the central hub of our Milky Way Galaxy.

[attachment=2903]
This illustration from a hypothetical planet
in a distant ultradense galaxy reveals a sky
packed with thousands of stars. There are 200
 times more stars in this sky than in our Earth's
 nighttime sky. Credit: NASA, ESA, G. Bacon (STScI),
 and P. van Dokkum (Yale University)
 

 
Astronomers used NASA's Hubble Space Telescope and the W.M. Keck Observatory on Mauna Kea, Hawaii, to study the galaxies as they existed 11 billion years ago, when the universe was less than 3 billion years old.

"Seeing the compact sizes of these galaxies is a puzzle," said Pieter G. van Dokkum of Yale University in New Haven, Conn., who led the study. "No massive galaxy at this distance has ever been observed to be so compact. It is not yet clear how they would build themselves up to become the large galaxies we see today. They would have to change a lot over 11 billion years, growing five times bigger. They could get larger by colliding with other galaxies, but such collisions may not be the complete answer."

To determine the sizes of the galaxies, the team used the Near Infrared Camera and Multi-Object Spectrometer on Hubble. The Keck observations were carried out with assistance of a powerful laser to correct for image blurring caused by the Earth's atmosphere. "Only Hubble and Keck can see the sizes of these galaxies because they are very small and far away," van Dokkum explained.

Van Dokkum and his colleagues studied the galaxies in 2006 with the Gemini South Telescope Near-Infrared Spectrograph, on Cerro Pachon in the Chilean Andes. Those observations provided the galaxies' distances and showed that the stars are a half a billion to a billion years old. The most massive stars had already exploded as supernovae.

"In the Hubble Deep Field, astronomers found that star-forming galaxies are small," said Marijn Franx of Leiden University, The Netherlands. "However, these galaxies were also very low in mass. They weigh much less than our Milky Way. Our study, which surveyed a much larger area than in the Hubble Deep Field, surprisingly shows that galaxies with the same weight as our Milky Way were also very small in the past. All galaxies look really different in early times, even massive ones that formed their stars early."

[attachment=2901]
This illustration shows the comparative sizes
 of our Milky Way Galaxy and an ultracompact
galaxy, which existed in the early universe.
 Although the compact galaxy is only a fraction
 of the size of our Milky Way, it contains the
same number of stars. The small, dense galaxy
could fit inside the central hub of our Milky Way.
 Credit: NASA, ESA, A. Feild (STScI), and P.
van Dokkum (Yale University)
 

 
The ultradense galaxies might comprise half of all galaxies of that mass 11 billion years ago, van Dokkum said, forming the building blocks of today's largest galaxies.

How did these small, crowded galaxies form? One way, suggested van Dokkum, involves the interaction of dark matter and hydrogen gas in the nascent universe. Dark matter is an invisible form of matter that accounts for most of the universe's mass. Shortly after the Big Bang, the universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in puddles of the invisible material and began spinning rapidly in dark matter's gravitational whirlpool, forming stars at a furious rate.

Based on the galaxies' masses, which are derived from their color, the astronomers estimated that the stars are spinning around their galactic disks at roughly 890,000 to 1 million miles an hour (400 to 500 kilometers a second). Stars in today's galaxies, by contrast, are traveling at about half that speed because they are larger and rotate more slowly than the compact galaxies.

These galaxies are ideal targets for the Wide Field Camera 3, which is scheduled to be installed aboard Hubble during Servicing Mission 4 in the fall of 2008. "We hope to use the Wide Field Camera 3 to find thousands of these galaxies. The Hubble images, together with the laser adaptive optics at Keck and similar large telescopes, should lead to a better understanding of the evolution of galaxies early in the life of the universe," said Garth Illingworth of the University of California, Santa Cruz, and Lick Observatory.

The findings appeared in the April 10 issue of The Astrophysical Journal Letters.
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Moon Meets Mercury
Credit & Copyright: P-M Hedén (Clear Skies, TWAN)


[attachment=2971]





 On Tuesday, May 6, while standing on planet Earth and sweeping your binoculars along the western horizon just after sunset, you might have encountered this arresting skyscape. The view features a slender crescent Moon and bright planet Mercury separated on the sky by only about 2 degrees. Cradled in the sunlit lunar crescent, the night side of the Moon is faintly illuminated by earthshine -- sunlight reflected from planet Earth. Of course, the clouds in silhouette and fading twilight colors are common elements in pictures of the sky after sunset, but much less often seen is inner planet Mercury, usually hiding close to the Sun in Earth's sky. Still, the coming week will be a good time to spot Mercury near the western horizon about 30 minutes after sunset. As for the Moon, tonight and tomorrow night the crescent Moon will wander close to Mars in the early evening sky.
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The Gegenschein Over Chile
Credit & Copyright: Yuri Beletsky (ESO)


[attachment=2973]

BIG PICCY HERE



 Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above from last October is one of the most spectacular pictures of the gegenschein yet taken. Here a deep exposure of an extremely dark sky over Paranal Observatory in Chile shows the gegenschein so clearly that even a surrounding glow is visible. In the foreground are several of the European Southern Observatory's Very Large Telescopes, while notable background objects include the Andromeda galaxy toward the lower left and the Pleiades star cluster just above the horizon. The gegenschein is distinguished from zodiacal light near the Sun by the high angle of reflection. During the day, a phenomenon similar to the gegenschein called the glory can be seen in reflecting air or clouds opposite the Sun from an airplane.


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Part of missing matter in the universe now discovered
EUROPEAN SPACE AGENCY NEWS RELEASE


ESA's orbiting X-ray observatory XMM-Newton has been used by a team of international astronomers to uncover part of the missing matter in the universe.

Ten years ago, scientists predicted that about half of the 'ordinary' or normal matter made of atoms exists in the form of low-density gas, filling vast spaces between galaxies.
 
[attachment=3043]

Composite optical and X-ray image of galaxy
clusters Abell 222 and Abell 223. The cluster
 pair is connected by a filament permeated by
 hot X-ray emitting gas. Credits:
 ESA/ XMM-Newton/ EPIC/ ESO (J. Dietrich)/
 SRON (N. Werner)/ MPE (A. Finoguenov)
 

 
All the matter in the universe is distributed in a web-like structure. At dense nodes of the cosmic web are clusters of galaxies, the largest objects in the universe. Astronomers suspected that the low-density gas permeates the filaments of the web.

The low density of the gas hampered many attempts to detect it in the past. With XMM-Newton's high sensitivity, astronomers have discovered its hottest parts. The discovery will help them understand the evolution of the cosmic web.

Only about 5% of our universe is made of normal matter as we know it, consisting of protons and neutrons, or baryons, which along with electrons, form the building blocks of ordinary matter. The rest of our universe is composed of elusive dark matter (23%) and dark energy (72%).   

Small as the percentage might be, half of the ordinary baryonic matter is unaccounted for. All the stars, galaxies and gas observable in the universe account for less than a half of all the baryons that should be around.

Scientists predicted that the gas would have a high temperature and so it would primarily emit low-energy X-rays. But its very low density made observation difficult.

Astronomers using XMM-Newton were observing a pair of galaxy clusters, Abell 222 and Abell 223, situated at a distance of 2300 million light-years from Earth, when the images and spectra of the system revealed a bridge of hot gas connecting the clusters.

"The hot gas that we see in this bridge or filament is probably the hottest and densest part of the diffuse gas in the cosmic web, believed to constitute about half the baryonic matter in the universe," says Norbert Werner from SRON Netherlands Institute for Space Research, leader of the team reporting the discovery.

"The discovery of the warmest of the missing baryons is important. That's because various models exist and they all predict that the missing baryons are some form of warm gas, but the models tend to disagree about the extremes," adds Alexis Finoguenov, a team member.

Even with XMM-Newton's sensitivity, the discovery was only possible because the filament is along the line of sight, concentrating the emission from the entire filament in a small region of the sky. The discovery of this hot gas will help better understand the evolution of the cosmic web.

"This is only the beginning. To understand the distribution of the matter within the cosmic web, we have to see more systems like this one. And ultimately launch a dedicated space observatory to observe the cosmic web with a much higher sensitivity than possible with current missions. Our result allows to set up reliable requirements for those new missions." concludes Norbert Werner.

ESA's XMM-Newton Project Scientist, Norbert Schartel, comments on the discovery, "This important breakthrough is great news for the mission. The gas has been detected after hard work and more importantly, we now know where to look for it. I expect many follow-up studies with XMM-Newton in the future targeting such highly promising regions in the sky."
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Hubble sees the Antennae Galaxies moving closer
HUBBLE EUROPEAN SPACE AGENCY INFORMATION CENTRE RELEASE

New research on the Antennae Galaxies using the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope shows that this benchmark pair of interacting galaxies is in fact much closer than previously thought - 45 million light-years instead of 65 million light-years.

[attachment=3045]
Credit: NASA, ESA & Ivo Saviane (European Southern Observatory)
 See larger image here
 
 
The Antennae Galaxies are among the closest known merging galaxies. The two galaxies, also known as NGC 4038 and NGC 4039, began interacting a few hundred million years ago, creating one of the most impressive sights in the night sky. They are considered by scientists as the archetypal merging galaxy system and are used as a standard against which to validate theories about galaxy evolution.

An international group of scientists led by Ivo Saviane from the European Southern Observatory has used Hubble's Advanced Camera for Surveys and Wide Field Planetary Camera 2 to observe individual stars spawned by the colossal cosmic collision in the Antennae Galaxies. They reached an interesting and surprising conclusion. By measuring the colours and brightnesses of red giant stars in the system, the scientists found that the Antennae Galaxies are much closer than previously thought: 45 million light-years instead of the previous best estimate of 65 million light-years.

The team targeted a region in the relatively quiescent outer regions in the southern tidal tail, away from the active central regions. This tail consists of material thrown from the main galaxies as they collided. The scientists needed to observe regions with older red giant stars to derive an accurate distance. Red giants are known to reach a standard brightness, which can then be used to infer their distance. The method is known as the tip of the red giant branch (TRGB).

The proximity of the Antennae system means it is the best-studied galaxy merger in the sky, with a wealth of observational data to be compared to the predictions of theoretical models. Saviane says: "All aspiring models for galaxy evolution must be able to account for the observed features of the Antennae Galaxies, just as respectable stellar models must be able to match the observed properties of the Sun. Accurate models require the correct merger parameters, and of these, the distance is the most essential".

The previous canonical distance to the Antennae Galaxy was about 65 million light-years although values as high as 100 million light years have been used. Our Sun is only eight light-minutes away from us, so the Antennae Galaxies may seem rather distant, but if we consider that we already know of galaxies that are more than ten billion light-years away, the two Antennae Galaxies are really our neighbours.

The previous larger distance required astronomers to invoke some quite exceptional physical characteristics to account for the spectacular system: very high star-formation rates, supermassive star clusters, ultraluminous X-ray sources etc. The new smaller distance makes the Antennae Galaxies less extreme in terms of the physics needed to explain the observed phenomena. For instance, with the smaller distance its infrared radiation is now that expected of a 'standard' early merging event rather than that of an ultraluminous infrared galaxy. The size of the star clusters formed as a consequence of the Antennae merger now agree with those of clusters created in other mergers instead of being 1.5 times as large.

The Antennae Galaxies are named for the two long tails of stars, gas and dust that resemble the antennae of an insect. These 'antennae' are a physical result of the collision between the two galaxies. Studying their properties gives us a preview of what may happen when our Milky Way galaxy collides with the neighbouring Andromeda galaxy in several billion years. Although galaxy mergers today are not common, it is believed that in the past they were an important channel of galaxy evolution. Therefore understanding the physics of galaxy mergers is a very important task for astrophysicists.

The Antennae are located in the constellation of Corvus, the Crow.

The findings appeared in the May 2008 issue of The Astrophysical Journal.
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ARCHEOLOGY
Oldest bust of Caesar found in France

French archaeologists have found what is thought to be the oldest existing statue of Julius Caesar in southern France. The bust is believed to be the sole portrait made during his life.

A bust of Julius Caesar, believed to be the oldest representation of the Roman emperor yet known, has been found at the bottom of the River Rhone in Arles, a town founded by him in 46 BC, the French culture ministry said Tuesday.
 
The imperial bust, showing a balding and aging man, was found with other artefacts in the bed of the river in the south of France.

 
It is "the oldest representation yet known of Caesar," and "typical of a series of realistic portraits from the period of the (Roman) republic," said a ministry statement.
 
Three other statues, including one of the god Neptune dating from the beginning of the third century AD, were found at the same site.
 
"I suspect the bust was thrown in the river after he was assassinated  because it would not have been good at that time to be considered a follower of his," said French archaeologist Luc Long, who directed excavations at the underwater site.
 
"In Rome you don't find any statues of Caesar dating from the time he lived, they were all posthumous," he added.


[attachment=3047]



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Discovery of most recent supernova in our galaxy
NASA NEWS RELEASE


WASHINGTON -- The most recent supernova in our galaxy has been discovered by tracking the rapid expansion of its remains. This result, using NASA's Chandra X-ray Observatory and the National Radio Astronomy Observatory's Very Large Array, will help improve our understanding of how often supernovae explode in the Milky Way galaxy.



[attachment=3103]

Credit: X-ray (NASA/CXC/NCSU/S.Reynolds et al.
); Radio (NSF/NRAO/VLA/Cambridge/D.Green et al.)

 
 
The supernova explosion occurred about 140 years ago, making it the most recent in the Milky Way. Previously, the last known supernova in our galaxy occurred around 1680, an estimate based on the expansion of its remnant, Cassiopeia A.

Finding such a recent, obscured supernova is a first step in making a better estimate of how often the stellar explosions occur. This is important because supernovae heat and redistribute large amounts of gas, and pump heavy elements out into their surroundings. They can trigger the formation of new stars as part of a cycle of stellar death and rebirth. The explosion also can leave behind, in addition to the expanding remnant, a central neutron star or black hole.

The recent supernova explosion was not seen with optical telescopes because it occurred close to the center of the galaxy and is embedded in a dense field of gas and dust. This made the object about a trillion times fainter, in optical light, than an unobscured supernova. However, the remnant it caused can be seen by X-ray and radio telescopes.

"We can see some supernova explosions with optical telescopes across half of the universe, but when they're in this murk we can miss them in our own cosmic backyard," said Stephen Reynolds of North Carolina State University in Raleigh, who led the Chandra study. "Fortunately, the expanding gas cloud from the explosion shines brightly in radio waves and X-rays for thousands of years. X-ray and radio telescopes can see through all that obscuration and show us what we've been missing."

Astronomers regularly observe supernovae in other galaxies like ours. Based on those observations, researchers estimate about three explode every century in the Milky Way.

"If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions that are younger than Cassiopeia A," said David Green of the University of Cambridge in the United Kingdom, who led the Very Large Array study. "It's great to finally track one of them down."

[attachment=3105]
Clear expansion is seen between these Very
Large Array images obtained in 1985 and 2008.
 Credit: NSF/NRAO/VLA/Cambridge/D.Green et al.

 
 
The tracking of this object began in 1985, when astronomers, led by Green, used the Very Large Array to identify the remnant of a supernova explosion near the center of our galaxy. Based on its small size, it was thought to have resulted from a supernova that exploded about 400 to 1000 years ago.

Twenty-two years later, Chandra observations revealed the remnant had expanded by a surprisingly large amount, about 16 percent, since 1985. This indicates the supernova remnant is much younger than previously thought.

That young age was confirmed in recent weeks when the Very Large Array made new radio observations. This comparison of data pinpoints the age of the remnant at 140 years - possibly less if it has been slowing down - making it the youngest on record in the Milky Way.

Besides being the record holder for youngest supernova, the object is of considerable interest for other reasons. The high expansion velocities and extreme particle energies that have been generated are unprecedented and should stimulate deeper studies of the object with Chandra and the Very Large Array.

"No other object in the galaxy has properties like this," Reynolds said. "This find is extremely important for learning more about how some stars explode and what happens in the aftermath."

SOURCE: SPACEFLIGHNOW.COM
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The Perseus Cluster of Galaxies
Credit & Copyright:
 Jean-Charles Cuillandre (CFHT) & Giovanni
Anselmi (Coelum Astronomia), Hawaiian Starlight


[attachment=3135]

BIGGER PICCY HERE


 Here is one of the largest objects that anyone will ever see on the sky. Each of these fuzzy blobs is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through a foreground of faint stars in our own Milky Way Galaxy. Near the cluster center, roughly 250 million light-years away, is the cluster's dominant galaxy NGC 1275, seen above as the large galaxy on the image left. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as gas and galaxies fall into it. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster spanning over 15 degrees and containing over 1,000 galaxies. At the distance of NGC 1275, this view covers about 1.5 million light-years.
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A Fire Rainbow Over New Jersey
Credit & Copyright: Paul Gitto (Arcturus Observatory)


[attachment=3196]




What is that inverted rainbow in the sky? Sometimes known as a fire rainbow for its flame-like appearance, a circumhorizon arc is created by ice, not fire. For a circumhorizon arc to be visible, the Sun must be at least 58 degrees high in a sky where cirrus clouds are present. Furthermore, the numerous, flat, hexagonal ice-crystals that compose the cirrus cloud must be aligned horizontally to properly refract sunlight like a single gigantic prism. Therefore, circumhorizon arcs are quite unusual to see. Pictured above, however, a rare fire rainbow was captured above trees in Whiting, New Jersey, USA in late May.
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BLAST OFF
Image Credit: Jerry Cannon, Robert Murray, NASA

[attachment=3240]





Rising through a billowing cloud of smoke, this Delta II rocket left Cape Canaveral Air Force Station's launch pad 17-B Wednesday at 12:05 pm EDT. Snug in the payload section was GLAST, the Gamma-ray Large Area Space Telescope, now in orbit around planet Earth. GLAST's detector technology was developed for use in terrestrial particle accelerators. But from orbit, GLAST can study gamma-rays from extreme environments in our own Milky Way galaxy, as well as supermassive black holes at the centers of distant active galaxies, and the sources of powerful gamma-ray bursts. Those cosmic accelerators achieve energies not attainable in earthbound laboratories. GLAST also has the sensitivity to search for signatures of new physics in the relatively unexplored high-energy gamma-ray regime.
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Pluto assigned 'plutoid' tag
 in new IAU classification

BY DR EMILY BALDWIN
ASTRONOMY NOW
Posted: June 12, 2008


Almost two years after the International Astronomical Union (IAU) caused a worldwide furore by stripping Pluto of its former status as a 'proper' planet to a dwarf planet, the term 'plutoid' has been introduced to describe "Pluto-like transneptunian dwarf planets".


[attachment=3254]
The IAU's new Solar System, as defined in 2006,
 with Pluto, Eris and Ceres named as dwarf planets.
 Now, Pluto and Eris are plutoids, while Ceres
 remains a dwarf planet. Image: IAU.


The original demotion of Pluto to a dwarf planet came about as a result of numerous discoveries of Pluto-like bodies, some even larger in size, in the far reaches of our Solar System. If they were treated the same as Pluto, they too would have to be called planets, taking the Solar System’s planet inventory to more than 50, a prospect that was even less favourable than relegating just one planet to a sub-category, which also included the bodies Ceres and Eris.

Now, the IAU have once again re-written the textbooks to introduce a new term – 'plutoid' – to describe “celestial bodies in orbit around the Sun at a distance greater than that of Neptune, that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a near-spherical shape, and that have not cleared the neighbourhood around their orbit of debris”. The body must also have an absolute magnitude brighter than +1 to be considered as a plutoid and be named by the IAU as one. If, subsequently, the plutoid candidate turns out to not be massive enough to be classified as one, it will still keep its name, but will change category.


[attachment=3252]
The new plutoid category of Solar System bodies
 includes Pluto and its moons Charon, Hydra and
 Nix (left) and Eris and its moon Dysnomia (right)
. Image: IAU.

The new classification systems means that while Pluto and Eris are the first plutoids of the Solar System, Ceres remains a dwarf planet, because it is located in the asteroid belt between Mars and Jupiter. It is expected that more plutoids will be named as science progresses and new discoveries are made.

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M51 Hubble Remix
Credit: S. Beckwith (STScI),
 Hubble Heritage Team, (STScI/AURA), ESA, NASA
Additional Processing: Robert Gendler




[attachment=3273]


 The 51st entry in Charles Messier's famous catalog is perhaps the original spiral nebula - a large galaxy with a well defined spiral structure also cataloged as NGC 5194. Over 60,000 light-years across, M51's spiral arms and dust lanes clearly sweep in front of its companion galaxy (right), NGC 5195. Image data from the Hubble's Advanced Camera for Surveys has been reprocessed to produce this alternative portrait of the well-known interacting galaxy pair. The processing has further sharpened details and enhanced color and contrast in otherwise faint areas, bringing out dust lanes and extended streams that cross the small companion, along with features in the surroundings and core of M51 itself. The pair are about 31 million light-years distant. Not far on the sky from the handle of the Big Dipper, they officially lie within the boundaries of the small constellation Canes Venatici.
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Phoenix Digs for Clues on Mars
Credit: Phoenix Mission Team, NASA,
 JPL-Caltech, U. Arizona, Texas A&M University



[attachment=3290]

 What's a good recipe for preparing Martian soil? Start by filling your robot's scoop a bit less than half way. Next, dump your Martian soil into one of your TEGA ovens, being sure to watch out for clumping. Then, slowly increase the temperature to over 1000 degrees Celsius over several days. Keep checking to see when your soil becomes vaporized. Finally, your Martian soil is not ready for eating, but rather sniffing The above technique is being used by the Phoenix Lander that arrived on Mars three weeks ago. Data from the first batch of baked soil should be available in a few days. Pictured above, a circular array of the Phoenix Lander's solar panels are visible on the left, while a scoop partly filled with Martian soil is visible on the right. The robotic Phoenix Lander will spend much of the next three months digging, scooping, baking, sniffing, zapping, dissolving, and magnifying bits of Mars to help neighboring Earthlings learn more about the hydrologic and biologic possibilities of the sometimes mysterious red planet.
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Eta Carinae and the Homunculus Nebula
Credit: N. Smith, J. A. Morse (U. Colorado) et al., NASA

[attachment=3300]


 How did the star Eta Carinae create this unusual nebula? No one knows for sure. About 165 years ago, the southern star Eta Carinae mysteriously became the second brightest star in the night sky. In 20 years, after ejecting more mass than our Sun, Eta Car unexpected faded. This outburst appears to have created the Homunculus Nebula, pictured above in a composite image from the Hubble Space Telescope taken last decade. Visible in the above image center is purple-tinted light reflected from the violent star Eta Carinae itself. Surrounding this star are expanding lobes of gas laced with filaments of dark dust. Jets bisect the lobes emanating from the central star. Surrounding these lobes are red-tinted debris captured only by its glow in a narrow band of red light. This debris is expanding most quickly of all, and includes streaming whiskers and bow shocks caused by collisions with previously existing material. Eta Car still undergoes unexpected outbursts, and its high mass and volatility make it a candidate to explode in a spectacular supernova sometime in the next few million years.
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Pickering's Triangle from Kitt Peak
Credit & Copyright: T. Rector (U. Alaska Anchorage), H. Schweiker, WIYN, NOAO, AURA, NSF

[attachment=3526]

Biggy Piccy Here...it's worth it !!

 Wisps like this are all that remain visible of a Milky Way star. About 7,500 years ago that star exploded in a supernova leaving the Veil Nebula, also known as the Cygnus Loop. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history. Today, the resulting supernova remnant has faded and is now visible only through a small telescope directed toward the constellation of Cygnus. The remaining Veil Nebula is physically huge, however, and even though it lies about 1,400 light-years distant, it covers over five times the size of the full Moon. In images of the complete Veil Nebula, studious readers should be able to identify the Pickering's Triangle component pictured above, a component named for a famous astronomer and the wisp's approximate shape. The above image is a mosaic from the 4-meter Mayall telescope at the Kitt Peak National Observatory located in Arizona, USA.
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Shadow of a Martian Robot
Credit: Mars Exploration Rover Mission, JPL, NASA


[attachment=3528]

What if you saw your shadow on Mars and it wasn't human? Then you might be the Opportunity rover currently exploring Mars. Opportunity and sister robot Spirit have been probing the red planet since early 2004, finding evidence of ancient water, and sending breathtaking images across the inner Solar System. Pictured above, Opportunity looks opposite the Sun into Endurance Crater and sees its own shadow. Two wheels are visible on the lower left and right, while the floor and walls of the unusual crater are visible in the background. Opportunity and Spirit have now spent over four years exploring the red world, find new clues into the wet ancient past of our Solar System's second most habitable planet.
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The tiny star with a monster roar
BY DR EMILY BALDWIN
ASTRONOMY NOW
Posted: May 20, 2008


The brightest flare ever seen from a normal star other than our Sun, worth thousands of solar flares, has been released from a star that shines with just one percent of the Sun’s light.

EV Lacertae is a fairly normal red dwarf, the most common type of star in the Universe, and is one of our closest stellar neighbours at a distance of just 16 light-years. But weighing in at less than one-third the mass of the Sun and offering a faint magnitude 10 glow, it is far below naked eye visibility. That is, until it released a monster flare, detected on April 25 by the Russian-built Konus instrument on NASA’s Wind satellite and followed up by the Swift satellite, that would have been easily visible with the naked eye if the star had been observable in the night sky at the time. The flare remained bright in X-rays for eight hours before settling back to normal and was so blinding it caused instruments onboard Swift to automatically shut down.


[attachment=3645]
An artist impression of the incredibly powerful
 flare that erupted from the red dwarf star EV
 Lacertae last month. Image: Casey Reed/NASA.


"This gives us a golden opportunity to study a stellar flare on a second-by-second basis to see how it evolved," says Stephen Drake of NASA Goddard.

EV Lacertae rotates once every four days, generating strong localised magnetic fields that make it over one hundred times as magnetically powerful as the Sun’s field. The energy stored in its magnetic field powers the giant flares. The star is also a youthful few hundred million years old, around 15 times younger than our Sun. Younger stars rotate faster and generate more powerful flares, so in its first billion years our own Sun must have let loose millions of energetic flares that would have profoundly affected Earth and the other planets.

"Flares like this would deplete the atmospheres of life-bearing planets, sterilising their surfaces," says Rachel Osten, a Hubble Fellow at the University of Maryland and NASA Goddard.

Because of EV Lacertae’s relative youth, studying this recent eruption will give scientists a window into our Solar System’s early history.

 
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