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Offline neilep

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Next solar cycle will likely start in March, NOAA says
NOAA NEWS RELEASE
Posted: April 29, 2007

The next 11-year cycle of solar storms will most likely start next March and peak in late 2011 or mid-2012 - up to a year later than expected - according to a forecast issued by the NOAA Space Environment Center in coordination with an international panel of solar experts. The NOAA Space Environment Center led the prediction panel and issued the forecast at its annual Space Weather Workshop in Boulder, Colo. NASA sponsored the panel.


The solar cycle. Credit: NOAA
 
 
Expected to start last fall, the delayed onset of Solar Cycle 24 stymied the panel and left them evenly split on whether a weak or strong period of solar storms lies ahead, but neither group predicts a record-breaker.

During an active solar period, violent eruptions occur more often on the sun. Solar flares and vast explosions, known as coronal mass ejections, shoot energetic photons and highly charged matter toward Earth, jolting the planet's ionosphere and geomagnetic field, potentially affecting power grids, critical military and airline communications, satellites, Global Positioning System (GPS) signals, and even threatening astronauts with harmful radiation. These same storms illuminate night skies with brilliant sheets of red and green known as auroras, or the northern or southern lights.

Solar cycle intensity is measured in maximum number of sunspots-dark blotches on the sun that mark areas of heightened magnetic activity. The more sunspots there are, the more likely it is that major solar storms will occur.

In the cycle forecast issued Wednesday, half of the panel predicts a moderately strong cycle of 140 sunspots, plus or minus 20, expected to peak in October 2011. The other half predicts a moderately weak cycle of 90 sunspots, plus or minus 10, peaking in August 2012. An average solar cycle ranges from 75 to 155 sunspots. The late decline of Cycle 23 has helped shift the panel away from its earlier leaning toward a strong Cycle 24. Now the group is evenly split between strong and weak.

The first year after solar minimum, marking the end of Cycle 23, will provide the information scientists need to arrive at a consensus. NOAA and the panel decided to issue their best estimate now and update the forecast as the cycle progresses, since NOAA Space Environment Center customers have been requesting a forecast for more than a year.

"By giving a long-term outlook, we're advancing a new field-space climate-that's still in its infancy," said retired Air Force Brig. Gen. David L. Johnson, director of the NOAA National Weather Service. "Issuing a cycle prediction of the onset this far in advance lies on the very edge of what we know about the sun."

Scientists have issued cycle predictions only twice before. In 1989, a panel met to predict Cycle 22, which peaked that same year. Scientists met again in September of 1996 to predict Cycle 23-six months after the cycle had begun. Both groups did better at predicting timing than intensity, according to NOAA Space Environment Center scientist Douglas Biesecker, who chairs the current panel. He describes the group's confidence level as "high" for its estimate of a March 2008 onset and "moderate" overall for the two estimates of peak sunspot number and when those peaks would occur.

One disagreement among the current panel members centers on the importance of magnetic fields around the sun's poles as the previous cycle decays. End-cycle polar fields are the bedrock of the approach predicting a weak Cycle 24. The strong-cycle forecasters place more importance on other precursors extending over a several-cycle history. Another clue will be whether Cycle 24 sunspots appear by mid 2008. If not, the strong-cycle group might change its forecast.

"The panelists in each camp have clear views on why they believe in their prediction, why they might be wrong, and what it would take to change their minds," said Biesecker. "We're on the verge of understanding and agreeing on which precursors are most important in predicting future solar activity."

The NOAA Space Environment Center is the nation's first alert of solar activity and its affects on Earth. Just as NOAA's hurricane experts predict the upcoming season of Atlantic storms and forecast individual hurricanes, the agency's space weather experts issue outlooks for the next 11-year solar cycle and warn of storms occurring on the sun that could impact Earth. Both the NOAA National Hurricane Center and NOAA Space Environment Center are among nine NOAA National Centers for Environmental Prediction, part of the NOAA National Weather Service. The NOAA Space Environment Center also is the world warning agency of the International Space Environment Service, a consortium of 11 member nations.

NOAA, an agency of the U.S. Commerce Department, is celebrating 200 years of science and service to the nation. From the establishment of the Survey of the Coast in 1807 by Thomas Jefferson to the formation of the Weather Bureau and the Commission of Fish and Fisheries in the 1870s, much of America's scientific heritage is rooted in NOAA. 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 the 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 60 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.COM
 

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AWESOME FOR PROF !


Hawking enjoys zero G
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: April 26, 2007

Physicist Stephen Hawking, the wheelchair-bound theorist known for his insights into the nature of black holes and gravity, experienced weightlessness today during an eagerly anticipated airplane ride off Florida's East Coast.


Credit: Zero Gravity Corp.
 
 
Attended by a team of physicians, nurses and supporters, Hawking enjoyed 20 to 25 seconds of weightlessness during eight parabolic arcs aboard the Zero Gravity Corp.'s Boeing 727 jet. Passengers on such flights are weightlessness as they "fall" toward Earth inside the plane's foam-padded interior.

At the bottom of each arc, the nose of the plane is pulled up, briefly subjecting the passengers to about 1.5 times the force of gravity. Hawking, who suffers from amyotrophic lateral sclerosis, or ALS - Lou Gehrigs Disease - was closely monitored throughout the afternoon flight. After returning to the Kennedy Space Center's shuttle runway, he was all smiles and officials said he enjoyed the ride.

"Many people have asked me why I am taking this flight," the renowned physicist told reporters earlier today at the Shuttle Landing Facility. "I am doing it for many reasons. First of all, I believe that life on Earth is at an ever increasing risk of being wiped out by a disaster, such as sudden global warming, nuclear war, a genetically engineered virus or other dangers.

"I think the human race has no future if it doesn't go into space. I therefore want to encourage public interest in space," he said, speaking through a computer in his famously robotic "voice." "I have long wanted to go into space and the zero gravity flight is a first step toward space travel. I also want to demonstrate to the public that everyone can participate in this type of weightless experience."

Peter Diamandidis, president of Zero Gravity Corp., said the flight was organized to benefit four charities - Easter Seals, the Starlight Starbright Children's Foundation, Augie's Quest and the X Prize Foundation. Eight seats were auctioned off, raising some $150,000. Rides on the plane normally sell for $3,500 per passenger.

"We're really excited," Diamandis said. "The entire team is pumped and ready to go to fulfill his dream of being weightless."

To ensure's Hawking's safety, the physicist was closely monitored by his personal team of physicians and nurses. During a test flight Wednesday using an eighth grade student as a stand in, the team perfected the way they will gently lower Hawking to the padded floor after each parabola to make sure he remains comfortable during the half-minute or so when he will be subjected to 1.5 times the normal force of gravity.

"We've done a tremendous amount to ensure safety on this flight," Diamandis said. "We feel we have an excellent safety plan."

Diamandis said Hawking's doctors planned to assess blood pressure, oxygen levels and other factors after the first parabola to make sure it is safe to proceed. Diamandis said he would be happy with a single parabola, prompting Hawking to interject a computer-synthesized "no!"

"As you can imagine, I am very excited," Hawking said earlier. "I have been wheelchair bound for almost four decades and the chance to float free in zero G will be wonderful."

Hawking is considered one of the world's leading authorities on quantum black holes and big bang cosmology. Along with his scholarly achievements, Hawking is the author of the popular bestseller "A Brief History of Time."

SOURCE:SPACEFLIGHTNOW.COM
 

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Black holes may fill the universe with seeds of life
HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS NEWS RELEASE
Posted: April 30, 2007

CAMBRIDGE, MA - New research shows that black holes are not the ultimate destroyers that are often portrayed in popular culture. Instead, warm gas escaping from the clutches of enormous black holes could be one source of the chemical elements that make life possible.


The black hole at the center of the NGC 4051 galaxy emits a hot wind of chemical elements,
 including elements like carbon and oxygen that are critical for life. The hot wind originates
 very close to the black hole, at a distance about five times the size of Neptune's orbit.
 Although speedy, the wind is weaker than expected and ejects only 2 to 5 percent of accreting
 material. Credit: George Seitz/Adam Block/NOAO/AURA/NSF
 

 
Immediately after the Big Bang, the universe contained only hydrogen and helium. Heavier chemical elements had to be cooked up inside the first stars, then scattered throughout space to be incorporated in next-generation stars and their planets. Black holes may have helped to distribute those elements across the cosmos.

Black holes are not all-consuming monsters. Until gas crosses the boundary known as the event horizon, it can still escape if it is heated sufficiently.

"One of the big questions in cosmology is how much influence massive black holes exert on their surroundings," said co-author Martin Elvis of the Harvard-Smithsonian Center for Astrophysics (CfA). "This research helps answer that question."

An international team of astronomers has found that hot winds from giant black holes in galactic centers may blow heavy elements like carbon and oxygen into the vast tracts of space between galaxies.

The team, led by Yair Krongold of the Universidad Nacional Autonoma de Mexico, studied the supermassive black hole at the center of the galaxy NGC 4051. They found that gas was escaping from much closer to the black hole than previously thought. The outflow source is located about 2,000 Schwarzschild radii from the black hole, or about five times the size of Neptune's orbit. (The Schwarzschild radius is the black hole's "point of no return" - about 4 million miles for the black hole in NGC 4051.)

The team could also determine the fraction of gas that was avoiding being swallowed. That fraction ended up being smaller than earlier studies suggested.

"We calculate that between 2 to 5 percent of the accreting material is flowing back out," says team member Fabrizio Nicastro of the CfA.

Winds from black holes have been clocked at speeds of up to 4 million miles per hour. Over thousands of years, the chemical elements such as carbon and oxygen in those winds can travel immense distances, eventually becoming incorporated into the cosmic clouds of gas and dust, called nebulae, that will form new stars and planets.

This research, which used data from the European Space Agency's XMM-Newton satellite, is being reported in the April 20 issue of The Astrophysical Journal.
 
 

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Spitzer digs up hidden stars
HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS NEWS RELEASE
Posted: May 3, 2007

CAMBRIDGE, MA - Two rambunctious young stars are destroying their natal dust cloud with powerful jets of radiation, in an infrared image from NASA's Spitzer Space Telescope. The stars are located approximately 600 light-years away in a cosmic cloud called BHR 71.


Credit: NASA/JPL-Caltech/T. Bourke (CfA)
 
 
"BHR 71 has been a favorite object of mine for years," said Tyler Bourke of the Harvard-Smithsonian Center for Astrophysics. "This spectacular new Spitzer image really shows off the changes in the jets, in ways impossible at other wavelengths."

The visible light image (left) was taken by the European Space Agency's ground-based Very Large Telescope. In this image BHR 71 is just a large black structure. The burst of yellow light toward the bottom of the cloud is the only indication that stars might be forming inside.

In the infrared image (middle), the baby stars are shown as the bright yellow smudges toward the center. Both of these yellow spots have wisps of green shooting out of them. The green wisps reveal the beginning of a jet. Like a rainbow, the jet begins as green, then transitions to orange, and red toward the end.

The jets' changing colors reveals a cooling effect, and may suggest that the young stars are spouting out radiation in regular bursts. The green tints at the beginning of the jet reveal really hot hydrogen gas, the orange shows warm gas, and the wisps of red at the end represent the coolest gas.

The fact that gas toward the beginning of the jet is hotter than gas near the middle, suggests that the stars must give off regular bursts of energy - and the material closest to the star is being heated by shockwaves from a recent stellar outburst. Meanwhile, the tints of orange reveal gas that is currently being heated by shockwaves from a previous stellar outburst. By the time these shockwaves reach the end of the jet, they have slowed down so significantly that the gas is only heated a little, and looks red.

The combined visible-light infrared composite (right) shows that a young star's powerful jet is responsible for the rupture at the bottom of the dense cloud in the visible-light image. We know this because the burst of light in the visible-light image overlaps exactly with a jet spouting out of the left star, shown in the infrared image.

The combination of views also brings out some striking details that evaded visible-light detection. For example, the yellow dots scattered throughout the image are actually young stars forming inside BHR 71. Spitzer also uncovered another young star with jets, located to the right of the powerful jet seen in the visible-light image.

Spitzer can see details, that visible-light telescopes don't, because its infrared instruments are sensitive to "heat."

The infrared image is made up of data from Spitzer's infrared array camera. Blue shows infrared light at 3.6 microns, green is light at 4.5 microns, and red is light at 8.0 microns.
 

Offline Karen W.

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Green Glasses from Deep inside the Moon

John Longhi has pondered magma formation in the Moon for a long time, basing his work on careful experiments at high pressure and temperature, computer calculations based on the results of those experiments, and a vast knowledge of phase equilibria (what happens when rocks melt and crystallize). One of his interests has been the origin of the magma that produced the Apollo 15 green glass, a volcanic deposit. The green glass is what cosmochemists call "primitive," which means that it was not altered as it migrated from deep in the Moon to the surface. Thus, it reflects the composition of the lunar interior in the region where it formed.


                        lunar green glass



Spherules of green glass (most about 0.1 millimeter across) collected during the Apollo 15 mission. The spherules formed by fire fountaining, a type of volcanic eruption in which escaping gases disrupt the magma into countless droplets of magma (see PSRD article: Explosive Volcanic Eruptions on the Moon). The Apollo 15 green glass magma was modified only slightly if at all from the region of the lunar mantle in which it formed, so its composition provides a window to at least some parts of the lunar interior.

Citation: Taylor, G. J. (April, 2007) Two Views of the Moon's Composition. Planetary Science Research Discoveries.




« Last Edit: 16/06/2007 07:38:43 by Karen W. »
 

Offline Karen W.

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   Taken from National Aeronautics and space administration



FEATURE   
NASA Satellite Captures First View of 'Night-Shining Clouds'

   06.28.07

A NASA satellite has captured the first occurrence this summer of mysterious shiny polar clouds that form 50 miles above Earth’s surface.



   
FEATURE   
NASA Satellite Captures First View of 'Night-Shining Clouds'

   06.28.07

A NASA satellite has captured the first occurrence this summer of mysterious shiny polar clouds that form 50 miles above Earth’s surface.

One of the first ground sightings of noctilucent clouds in the 2007 season.
Click image to enlarge.

Image above: This image shows one of the first ground sightings of noctilucent clouds in the 2007 season. Credit: Veres Viktor of Budapest, Hungary taken on June 15, 2007.

The first observations of these "night-shining" clouds by a satellite named "AIM" which means Aeronomy of Ice in the Mesosphere, occurred above 70 degrees north latitude on May 25. People on the ground began seeing the clouds on June 6 over Northern Europe. AIM is the first satellite mission dedicated to the study of these unusual clouds.

These mystifying clouds are called Polar Mesospheric Clouds, or PMCs, when they are viewed from space and referred to as "night-shining" clouds or Noctilucent Clouds, when viewed by observers on Earth. The clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the Northern Hemisphere’s summer season which began in mid-May and extends through the end of August and are being seen by AIM’s instruments more frequently as the season progresses. They are also seen in the high latitudes during the summer months in the Southern Hemisphere.


   

 
Image above: On June 11, 2007 the cameras on the AIM satellite returned some of the first data documenting noctilucent clouds over the Arctic regions of Europe and North America. This new data reveals the global extent and structure of these mysterious clouds, to a degree that was previously unattainable. White and light blue represent noctilucent cloud structures. Black indicates areas where no data is available. Credit: Cloud Imaging and Particle Size Experiment data processing team at the University of Colorado Laboratory for Atmospheric and Space Physics

Very little is known about how these clouds form over the poles, why they are being seen more frequently and at lower latitudes than ever before, or why they have been growing brighter. AIM will observe two complete cloud seasons over both poles, documenting an entire life cycle of the shiny clouds for the first time.

"It is clear that these clouds are changing, a sign that a part of our atmosphere is changing and we do not understand how, why or what it means," stated AIM principal investigator James Russell III of Hampton University, Hampton, Va. "These observations suggest a connection with global change in the lower atmosphere and could represent an early warning that our Earth environment is being changed."

AIM is providing scientists with information about how many of these clouds there are around the world and how different they are including the sizes and shapes of the tiny particles that make them up. Scientists believe that the shining clouds form at high latitudes early in the season and then move to lower latitudes as time progresses. The AIM science team is studying this new data to understand why these clouds form and vary, and if they may be related to global change.

Once the summer season ends in the Northern Hemisphere around mid- to late August, the Southern Hemisphere spring season starts about three months later in the period around mid- to late November. AIM will then be watching for shining clouds in the Southern Hemisphere from November through mid-March when that season ends.

AIM and is managed at Goddard Space Flight Center, Greenbelt, Md and the AIM Project Data Center is located at Hampton University.


Cynthia O'Carroll
Goddard Space Flight Center
   



« Last Edit: 18/07/2007 22:32:20 by Karen W. »
 

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Stellar explosion brightest supernova ever seen
UNIVERSITY OF CALIFORNIA-BERKELEY NEWS RELEASE


BERKELEY -- An exploding star first observed last September is the largest and most luminous supernova ever seen, according to University of California, Berkeley, astronomers, and may be the first example of a type of massive exploding star rare today but probably common in the very early universe.


The brightest stellar explosion ever recorded may be a long-sought new type
of supernova, according to observations by NASA's Chandra X-ray Observatory
and ground-based optical telescopes. Credit: Illustration: NASA/CXC/M.Weiss;
 X-ray: NASA/CXC/UC Berkeley/N.Smith et al.; IR: Lick/UC Berkeley/J.Bloom & C.Hansen


Unlike typical supernovas that reach a peak brightness in days to a few weeks and then dim into obscurity a few months later, SN2006gy took 70 days to reach full brightness and stayed brighter than any previously observed supernova for more than three months. Nearly eight months later, it still is as bright as a typical supernova at its peak, outshining its host galaxy 240 million light years away.

UC Berkeley post-doctoral fellows Nathan Smith and David Pooley estimate the star's mass at between 100 and 200 times that of the sun. Such massive stars are so rare that galaxies like our own Milky Way may contain only a dozen out of a stellar population of 400 billion.

"This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Smith, who led a team of astronomers from UC Berkeley and the University of Texas. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before."

"Of all exploding stars ever observed, this was the king," said Alex Filippenko, UC Berkeley astronomer and leader of the ground-based observations at the University of California's Lick Observatory in California and the W. M. Keck Observatory in Hawaii. "We were astonished to see how bright it got, and how long it lasted."


This artist's illustration shows what the brightest supernova ever recorded,
known as SN 2006gy, may have looked like. The fireworks-like material (white)
 shows the explosive death of an extremely massive star. Before it exploded,
 the star expelled the lobes of cool gas (red). As the material from the
explosion crashes into the lobes, it heats the gas in a shock front (green,
 blue and yellow) and pushes it backward. Credit: NASA/CXC/M.Weiss


Based on the Lick and Keck observations, plus data from the Chandra X-ray Observatory, Smith, Pooley, Filippenko and their colleagues argue that the stellar explosion was not your run-of-the-mill supernova, but a possible pair-instability supernova. They have submitted a paper describing the discovery and their conclusions to The Astrophysical Journal.

Stars with masses at least 10 times greater than our sun end their lives after burning hydrogen to helium, helium to carbon, and on to larger elements until they reach iron, when fusion stops. Toward the end of this process, the heat produced in the core of the star becomes insufficient to support the outer layers, which collapse inward, finishing the fusion process and crunching the core to a neutron star or black hole. The outer layers of the star are blown off in a bright flare-up we observe as a supernova.

For stars much more massive than this, ranging from 140 solar masses to as many as 250, the temperature at the core becomes so great that before the fusion cascade is complete, high-energy gamma rays in the core start annihilating one another, creating matter-antimatter pairs, mostly electron-positron pairs. Since gamma radiation is the energy that prevents collapse of the outer layers of the star, once the radiation starts disappearing, the outer layers fall inward. The net result is a thermonuclear explosion that, theoretically, would be brighter than any typical supernova. In this type of supernova, the star is blown to smithereens, leaving behind no black hole.

"This discovery forces us to go back to the drawing board to understand how the most massive stars die," Smith said. "Instead of just winking away into a black hole, they apparently can suffer these brilliant explosions that can be seen far across the universe. The fact that this thing is so bright, and stayed bright for a long time, makes our chances of detecting them in the early universe much better."


This graphic gives a summary of our best current understanding of the
 evolution of stars, showing their birth, middle age and eventual demise.
 Credit: NASA/CXC/M.Weiss


Such pair-instability supernovas should theoretically produce a greater percentage of heavy elements. According to Smith, the radioactive decay of nickel-56 produces most of the light of a supernova, and this pair-instability supernova produced about 20 solar masses of nickel, compared to maybe 0.6 solar masses in a Type Ia supernova. Astronomers think that a large proportion of the universe's first stars were supermassive stars like this that, upon exploding, seeded the early universe with the heavy elements from which planets and later, humans, were made.

"We may have witnessed a modern-day version of how the first generation of the most massive stars ended their lives, when the universe was very young," Filippenko said.

The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding, reminiscent of the star eta Carinae, a so-called luminous blue variable which, at 100 to 120 solar masses, is the most massive star in our galaxy.

"This is also very exciting because it suggests that eta Carinae, only 7,500 light years away, might possibly explode in a similar manner, becoming a spectacularly bright star in our sky," Filippenko said.

"We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case," added Mario Livio of the Space Telescope Science Institute in Baltimore, Md., who was not involved in the research. "Eta Carinae's explosion could be the best star-show in the history of modern civilization



Estimated to be 100 times heftier than our Sun, Eta Carinae is one of the
most massive stars in our galaxy. It may also turn out to be one of the
 shortest-lived, because results for SN 2006gy suggest that it may be
destroyed by a supernova at any time. This Hubble telescope image of
Eta Carinae shows a huge, billowing pair of gas and dust clouds, caused
by a giant eruption about 160 years ago, when it became one of the brightest
stars in the southern sky. Credit: NASA/N.Smith & J.Morse



University of Texas graduate student Robert Quimby first observed the supernova on Sept. 18, 2006 in the galaxy NGC 1260, located in the constellation Perseus. Filippenko's team immediately began observing it with its dedicated supernova search and monitor telescope at Lick, the Katzman Automatic Imaging Telescope.

Filippenko and his graduate student Ryan Foley subsequently obtained spectra of the star using the Lick 3-meter Shane telescope and the DEIMOS spectrograph mounted on the Keck II telescope.

Pooley led the Chandra observation, which allowed the team to rule out the most likely alternative explanation for the supernova, namely that it was an explosion of a white dwarf star into a dense, hydrogen-rich environment.

"If that were the case, this supernova would have been 1,000 times brighter in X-rays than what we detected with Chandra," said Pooley. "This must have been an extremely massive star."

"In terms of the effect on the early universe, there's a huge difference between these two possibilities," said Smith. "One pollutes the galaxy with large quantities of newly synthesized elements, and the other locks them up forever in a black hole."

"One exciting repercussion of this is that, if pair-instability supernovas really are this bright, it gives us hope that the James Webb Space Telescope might actually be able to detect these explosions from the first stars, thereby verifying that they may actually exist," he added.

The results from Smith, Pooley, Filippenko and their colleagues, including Weidong Li, Ryan Chornock, Jeffrey M. Silverman, Joshua S. Bloom and Charles Hansen of UC Berkeley and J. Craig Wheeler of the University of Texas, 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 work also was supported by the National Science Foundation and the W. M. Keck Foundation


SOURCE: SPACEFLIGHTNOW.COM














 

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Hubble observatory discovers ring of dark matter
HUBBLE ESA INFORMATION CENTRE NEWS RELEASE


An international team of astronomers using the NASA/ESA Hubble Space Telescope has discovered a ghostly ring of dark matter that was formed long ago during a titanic collision between two massive galaxy clusters. It is the first time that a dark matter distribution has been found that differs substantially from the distribution of ordinary matter.


This Hubble Space Telescope composite image shows a ghostly "ring" of dark
matter in the galaxy cluster ZwCl0024+1652. Credit: NASA, ESA, M.J. Jee and
 H. Ford (Johns Hopkins University)
Download larger image version here

 
 
Astronomers have long suspected the existence of the invisible substance of dark matter as the source of additional gravity that holds together galaxy clusters. Otherwise, astronomers say, the clusters would fly apart if they relied only on the gravity from their visible stars. Although astronomers don't know what dark matter is made of, they hypothesize that it is a type of elementary particle that pervades the Universe.

In a result just published, astronomers using the NASA/ESA Hubble Space Telescope report the discovery of a ring of dark matter in the cluster ZwCl0024+1652. The ring's discovery is among the strongest evidence yet that dark matter exists.

"This is the first time we have detected dark matter as having a unique structure that is different from the gas and galaxies in the cluster," said astronomer M. James Jee of Johns Hopkins University in Baltimore, USA, a member of the team that spotted the dark matter ring.

The ring, which measures 2.6 million light-years across, was found in the cluster ZwCl0024+1652, located 5 billion light-years away from Earth. The team found the ring unexpectedly while they were mapping the distribution of dark matter within the cluster. Although astronomers cannot see dark matter, they can infer its existence in galaxy clusters by observing how its gravity bends the light of more distant background galaxies.

"Although the invisible matter has been found before in other galaxy clusters, it has never been detected to be so largely separated from the hot gas and the galaxies that make up galaxy clusters," Jee continued. "By seeing a dark matter structure that is not traced by galaxies and hot gas, we can study how it behaves differently from normal matter."

During the team's dark-matter analysis, they noticed a ripple in the mysterious substance, somewhat like the ripples created in a pond from a stone plopping into the water.

"I was annoyed when I saw the ring because I thought it was an artifact, which would have implied a flaw in our data reduction," Jee explained. "I couldn't believe my result. But the more I tried to remove the ring, the more it showed up. It took more than a year to convince myself that the ring was real. I've looked at a number of clusters and I haven't seen anything like this."

Curious about why the ring was in the cluster and how it had formed, Jee found previous research that suggested the cluster had collided with another cluster 1 to 2 billion years ago. The research, published in 2002 by Oliver Czoske of the Argelander-Institut für Astronomie at Bonn University, was based on spectroscopic observations of the cluster's three-dimensional structure. The study revealed two distinct groupings of galaxies clusters, indicating a collision between both clusters.


SOURCE:SPACEFLIGHTNOW.COM
 

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Hubble catches Jupiter changing its stripes
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: July 9, 2007

Massive Jupiter is undergoing dramatic atmospheric changes that have never been seen before with the keen "eye" of NASA's Hubble Space Telescope.

Jupiter's turbulent clouds are always changing as they encounter atmospheric disturbances while sweeping around the planet at hundreds of miles per hour. But these Hubble images reveal a rapid transformation in the shape and color of Jupiter's clouds near the equator, marking an entire face of the globe.


Credit: NASA, ESA, A. Simon-Miller (NASA Goddard Space Flight Center), A. Sanchez-Lavega,
 R. Hueso, and S. Perez-Hoyos (University of the Basque Country), E. Garcia-Melendo
(Esteve Duran Observatory Foundation, Spain), and G. Orton (Jet Propulsion Laboratory)


 
The planet is wrapped in bands of yellows, browns, and whites. These bands are produced by the atmosphere flowing in different directions at various latitudes. Lighter-hued areas where the atmosphere rises are called zones. Darker regions where the atmosphere falls are called belts. When these opposing flows interact, storms and turbulence appear.

Between March 25 and June 5, Hubble's Wide Field and Planetary Camera 2 captured entire bands of clouds changing color. Zones have darkened into belts and belts have lightened and transformed into zones. Cloud features have rapidly altered in shape and size.

The image at left shows a thin band of white clouds above Jupiter's equator. The white color indicates clouds at higher altitudes in Jupiter's atmosphere. In the image at right, the band's white hue has turned brown, showing clouds deep within the planet's atmosphere. The whole band appears to have merged with the one below it.

In the same cloud band above the equator, the small swirls in the left-hand image have morphed into larger wave-like features in the right-hand photo. Dominating the band is a dark streak that resembles a snake. This serpent-shaped structure is actually a small tear in the cloud deck, which gives astronomers a view deep within the atmosphere.

Below the equatorial region, the brownish upside-down shark fin in the left-hand image disappears in the photo at right. Appearing instead are brownish tongue-shaped clouds with a stream of white swirls below them.

These global upheavals have been seen before, but not with Hubble's sharp resolution. Astronomers using ground-based telescopes first spied drastic atmospheric transformation in the 1980s. Another major disturbance was seen in the early 1990s, after Hubble was launched into space. The telescope, however, did not have the resolution to view the upheaval in fine detail. These higher-quality Hubble images may help astronomers understand how such global upheavals develop on Jupiter.


SOURCE:SPACEFLIGHTNOW.COM
 

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Stellar fireworks are ablaze in galaxy, Hubble shows
HUBBLE ESA INFORMATION CENTRE NEWS RELEASE
Posted: July 9, 2007


Credit: NASA, ESA, A. Aloisi (ESA/STScI) and The Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration
Download larger image version here
 
 
Nearly 12.5 million light-years away in the dwarf galaxy NGC 4449 a veritable stellar "fireworks" is on display - here shown in exquisite detail through the eyes of the Hubble Space Telescope.

Hundreds of thousands of vibrant blue and red stars are visible in this new image of galaxy NGC 4449 taken by the NASA/ESA Hubble Space Telescope. Hot bluish white clusters of massive stars are scattered throughout the galaxy, interspersed with numerous dustier reddish regions of current star formation. Massive dark clouds of gas and dust are silhouetted against the flaming starlight.

NGC 4449 has been forming stars since several billion years ago, but currently it is experiencing a star formation event at a much higher rate than in the past. This unusual explosive and intense star formation activity qualifies as a starburst. At the current rate, the gas supply that feeds the stellar production would only last for another billion years or so.

Starbursts usually occur in the central regions of galaxies, but NGC 4449 has a more widespread star formation activity, since the very youngest stars are observed both in the nucleus and in streams surrounding the galaxy.

A "global" starburst like NGC 4449 resembles primordial star forming galaxies which grew by merging with and accreting smaller stellar systems. Since NGC 4449 is close enough to be observed in great detail, it is the ideal laboratory for the investigation of what may have occurred during galactic formation and evolution in the early Universe.

It's likely that the current widespread starburst was triggered by interaction or merging with a smaller companion. NGC 4449 belongs to a group of galaxies in the constellation Canes Venatici, the Hunting Dogs. Astronomers think that NGC 4449's star formation has been influenced by interactions with several of its neighbours.

This image was taken in November 2005 by an international science team led by Alessandra Aloisi of European Space Agency (ESA)/the Space Telescope Science Institute (STScI) in Baltimore. Other team members include Francesca Annibali (STScI), Claus Leitherer (STScI), Jennifer Mack (STScI), Marco Sirianni (ESA/STScI), Monica Tosi (INAF-OAB), and Roeland van der Marel (STScI).

Hubble's Advanced Camera for Surveys observed the NGC 4449 in blue, visible, infrared, and Hydrogen-alpha light.

SOURCE:SPACEFLIGHTNOW.COM
 

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Planets with four parents?


How many stars does it take to "raise" a planet? In our own solar system, it took only one -- our Sun. However, new research from NASA's Spitzer Space Telescope shows that planets might sometimes form in systems with as many as four stars.


This artist concept depicts a quadruple-star system called HD 98800. The system is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae. Credit: NASA/JPL-Caltech/T. Pyle (SSC)
 
Astronomers used Spitzer's infrared vision to study a dusty disk that swirls around a pair of stars in the quadruple-star system HD 98800. Such disks are thought to give rise to planets. Instead of a smooth, continuous disk, the telescope detected gaps that could be caused by a unique gravitational relationship between the system's four stars. Alternatively, the gaps could indicate planets have already begun to form, carving out lanes in the dust.

"Planets are like cosmic vacuums. They clear up all the dirt that is in their path around the central stars," said Dr. Elise Furlan, of the NASA Astrobiology Institute at the University of California at Los Angeles. Furlan is the lead author of a paper that has been accepted for publication in The Astrophysical Journal.

HD 98800 is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae.

Before Spitzer set its gaze on HD 98800, astronomers had a rough idea of the system's structure from observations with ground-based telescopes. They knew the system contains four stars, and that the stars are paired off into doublets, or binaries. The stars in the binary pairs orbit around each other, and the two pairs also circle each other like choreographed ballerinas. One of the stellar pairs, called HD 98800B, has a disk of dust around it, while the other pair has none.

Although the four stars are gravitationally bound, the distance separating the two binary pairs is about 50 astronomical units (AU) -- slightly more than the average distance between our Sun and Pluto. Until now, technological limitations have hindered astronomers' efforts to look at the dusty disk around HD 98800B more closely.

With Spitzer, scientists finally have a detailed view. Using the telescope's infrared spectrometer, Furlan's team sensed the presence of two belts in the disk made of large dust grains. One belt sits at approximately 5.9 AU away from the central binary, HD 98800B, or about the distance from the Sun to Jupiter. This belt is likely made up of asteroids or comets. The other belt sits at 1.5 to 2 AU, comparable to the area where Mars and the asteroid belt sit, and probably consists of fine grains.

"Typically, when astronomers see gaps like this in a debris disk, they suspect that a planet has cleared the path. However, given the presence of the diskless pair of stars sitting 50 AU away, the inward-migrating dust particles are likely subject to complex, time-varying forces, so at this point the existence of a planet is just speculation," said Furlan.

Astronomers believe that planets form like snowballs over millions of years, as small dust grains clump together to form larger bodies. Some of these cosmic rocks then smash together to form rocky planets, like Earth, or the cores of gas-giant planets like Jupiter. Large rocks that don't form planets often become asteroids and comets. As these rocky structures violently collide, bits of dust are released into space. Scientists can see these dust grains with Spitzer's supersensitive infrared eyes.

According to Furlan, the dust generated from the collision of rocky objects in the outer belt should eventually migrate toward the inner disk. However, in the case of HD 98800B, the dust particles do not evenly fill out the inner disk as expected, due to either planets or the diskless binary pair sitting 50 AU away and gravitationally influencing the movement of dust particles.

"Since many young stars form in multiple systems, we have to realize that the evolution of disks around them and the possible formation of planetary systems can be way more complicated and perturbed than in a simple case like our solar system," Furlan added.


SOURCE: SPACEFLIGHTNOW.COM
 

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Cassini finds possible origin to one of Saturn's rings
NASA/JPL NEWS RELEASE


PASADENA, Calif. - Cassini scientists may have identified the source of one of Saturn's more mysterious rings. Saturn's G ring likely is produced by relatively large, icy particles that reside within a bright arc on the ring's inner edge.


Credit: NASA/JPL/Space Science Institute
 
 
The particles are confined within the arc by gravitational effects from Saturn's moon Mimas. Micrometeoroids collide with the particles, releasing smaller, dust-sized particles that brighten the arc. The plasma in the giant planet's magnetic field sweeps through this arc continually, dragging out the fine particles, which create the G ring.

The finding is evidence of the complex interaction between Saturn's moons, rings and magnetosphere. Studying this interaction is one of Cassini's objectives. The study is in the Aug. 2 issue of the journal Science and was based on observations made by multiple Cassini instruments in 2004 and 2005.

"Distant pictures from the cameras tell us where the arc is and how it moves, while plasma and dust measurements taken near the G ring tell us how much material is there," said Matthew Hedman, a Cassini imaging team associate at Cornell University in Ithaca, N.Y., and lead author on the Science paper.

Saturn's rings are an enormous, complex structure, and their origin is a mystery. The rings are labeled in the order they were discovered. From the planet outward, they are D, C, B, A, F, G and E. The main rings -- A, B and C from edge-to-edge, would fit neatly in the distance between Earth and the moon. The most transparent rings are D -- interior to C -- and F, E and G, outside the main rings.

Unlike Saturn's other dusty rings, such as the E and F rings, the G ring is not associated closely with moons that either could supply material directly to it -- as Enceladus does for the E ring -- or sculpt and perturb its ring particles -- as Prometheus and Pandora do for the F ring. The location of the G ring continued to defy explanation, until now.

Cassini images show that the bright arc within the G ring extends one-sixth of the way around Saturn and is about 250 kilometers (155 miles) wide, much narrower than the full 5,955-kilometer width (3,700 miles) of the G ring. The arc has been observed several times since Cassini's 2004 arrival at the ringed planet and thus appears to be a long-lived feature. A gravitational disturbance caused by the moon Mimas exists near the arc.

As part of their study, Hedman and colleagues conducted computer simulations that showed the gravitational disturbance of Mimas could indeed produce such a structure in Saturn's G ring. The only other places in the solar system where such disturbances are known to exist are in the ring arcs of Neptune.

Cassini's magnetospheric imaging instrument detected depletions in charged particles near the arc in 2005. According to the scientists, unseen mass in the arc must be absorbing the particles. "The small dust grains that the Cassini camera sees are not enough to absorb energetic electrons," said Elias Roussos of the Max-Planck-Institute for Solar System Research, Germany, and member of the magnetospheric imaging team. "This tells us that a lot more mass is distributed within the arc."

The researchers concluded that there is a population of larger, as-yet-unseen bodies hiding in the arc, ranging in size from that of peas to small boulders. The total mass of all these bodies is equivalent to that of an ice-rich, small moon that's about 100 meters wide (328 feet wide).

Joe Burns, a co-author of the paper from Cornell University and a member of the imaging team, said, "We'll have a super opportunity to spot the G ring's source bodies when Cassini flies about 600 miles from the arc 18 months from now."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, Pasadena, Calif., manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at the laboratory. The imaging team is based at the Space Science Institute, Boulder, Colo. The magnetospheric imaging instrument team is based at Johns Hopkins University, Laurel, Md.

SOURCE: SPACEFLIGHTNOW.COM
 

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A monster galaxy pileup
YALE UNIVERSITY NEWS RELEASE
Posted: August 6, 2007

NEW HAVEN, Conn. - Four galaxies are slamming into each other and kicking up billions of stars in one of the largest cosmic smash-ups ever observed.

The clashing galaxies, spotted by NASA's Spitzer Space Telescope and the WIYN Telescope, will eventually merge into a single, behemoth galaxy up to 10 times as massive as our own Milky Way. This rare sighting provides an unprecedented look at how the most massive galaxies in the universe form.


This artist's concept shows what the night sky might look like from
 a hypothetical planet around a star tossed out of the ongoing collision between big galaxies (yellow blobs). Credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA

 
 
"Most of the galaxy mergers we already knew about are like compact cars crashing together," said Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "What we have here is like four sand trucks smashing together, flinging sand everywhere." Rines, who was a Mead postdoctoral fellow at Yale from 2003-6 when much of this work was done, is lead author of a paper accepted for publication in Astrophysical Journal Letters.

Collisions, or mergers, between galaxies are common in the universe. Gravity causes some galaxies that are close together to tangle and ultimately unite over a period of millions of years. Though stars in merging galaxies are tossed around like sand, they have a lot of space between them and survive the ride. Our Milky Way galaxy will team up with the Andromeda galaxy in five billion years.

Mergers between one big galaxy and several small ones, called minor mergers, are well documented. For example, one of the most elaborate known minor mergers is taking place in the Spiderweb galaxy - a massive galaxy that is catching dozens of small ones in its "web" of gravity. Astronomers have also witnessed "major" mergers among pairs of galaxies that are similar in size. But no major mergers between multiple hefty galaxies - the big rigs of the galaxy world - have been seen until now.

The new quadruple merger was discovered serendipitously during a survey of a distant cluster of galaxies, called CL0958+4702, located nearly five billion light-years away. The telescopes first spotted an unusually large fan-shaped plume of light coming out of a gathering of four blob-shaped, or elliptical, galaxies. Three of the galaxies are about the size of the Milky Way, while the fourth is three times as big.

"The colors from the WIYN and Spitzer data show that the stars are old, but the higher resolution WIYN images show that the light from the disrupted galaxy does not have small-scale structure but is instead smoothly distributed telling us that the galaxies involved in the merger are elliptical rather than spiral galaxies," said Jeffrey Kenney, professor and chair of Astronomy at Yale.

According to Kenney, WIYN (named for it¹s joint ownership by the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatory) is one of the best imaging telescopes in the world. "The sharpness of the WIYN images helps show that we are in fact seeing a merger, and what type of galaxies have merged."

"The WIYN telescope provides some of the sharpest images possible from ground-based telescopes. The WIYN images show that the four galaxies have well-defined cores that have held together during the merger, much like egg yolks stay together longer than egg whites if you "merge" them in a mixing bowl," said Rines.

Further analysis of the plume revealed that it is made up of billions of older stars flung out and abandoned in an ongoing clash.  About half of the stars in the plume will later fall back into the galaxies. "When this merger is complete, this will be one of the biggest galaxies in the universe," said Rines.


One of the biggest galaxy collisions ever observed is taking place
at the center of this image. The four yellow blobs in the middle are
 large galaxies that have begun to tangle and ultimately merge into
 a single gargantuan galaxy. Credit: NASA/JPL-Caltech/CXO/WIYN/Harvard-Smithsonian CfA

 
 
The Spitzer observations also show that the new merger lacks gas. Theorists predict that massive galaxies grow in a variety of ways, including gas-rich and gas-poor mergers. In gas-rich mergers, the galaxies are soaked with gas that ignites to form new stars. Gas-poor mergers lack gas, so no new stars are formed. Spitzer found only old stars in the quadruple encounter.

"The Spitzer data show that these major mergers are gas-poor, unlike most mergers we know about," said Rines. "The data also represent the best evidence that the biggest galaxies in the universe formed fairly recently through major mergers."

Some of the stars tossed out in the monstrous merger will live in isolated areas outside the borders of any galaxies. Such abandoned stars could theoretically have planets. If so, the planets' night skies would be quite different from our own, with fewer stars and more visible galaxies.

In addition to Spitzer and WIYN, Rines and his team used a telescope formerly known as the Multiple Mirror Telescope and now called MMT near Tucson, Ariz., to confirm that the four galaxies are intertwined, and NASA's Chandra X-ray Observatory to weigh the mass of the giant cluster of galaxies in which the merger was discovered. Both Spitzer and WIYN, also near Tucson, Ariz., were used to study the plume.

Other authors of this paper include Rose Finn of Siena College, Loudonville, N.Y.; and Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics.

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 array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics.

 
SOURCE:SPACEFLIGHTNOW.COM
 

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Dark matter mystery deepens in 'train wreck'
CHANDRA X-RAY CENTER NEWS RELEASE
Posted: August 22, 2007

Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior.

"These results challenge our understanding of the way clusters merge," said Dr. Andisheh Mahdavi of the University of Victoria, British Columbia. "Or, they possibly make us even reexamine the nature of dark matter itself."


This multi-wavelength image of Abell 520 shows the aftermath of
 a complicated collision of galaxy clusters, some of the most massive objects in the
Universe. In this image, the hot gas as detected by Chandra is colored red. Optical data
 from the Canada-France-Hawaii and Subaru telescopes shows the starlight from the
individual galaxies (yellow and orange). The location of most of the matter in the
cluster (blue) was also found using these telescopes, by tracing the subtle
light-bending effects on distant galaxies. This material is dominated by dark matter.
Credit: X-ray: NASA/CXC/UVic./A.Mahdavi et al. Optical/Lensing: CFHT/UVic./A.Mahdavi et
 
 

 
There are three main components to galaxy clusters: individual galaxies composed of billions of stars, hot gas in between the galaxies, and dark matter, a mysterious substance that dominates the cluster mass and can be detected only through its gravitational effects.

Optical telescopes can observe the starlight from the individual galaxies, and can infer the location of dark matter by its subtle light-bending effects on distant galaxies. X-ray telescopes like Chandra detect the multimillion-degree gas.

A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies.

"It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves."

In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies.

"The observation of this group of galaxies that is almost devoid of dark matter flies in the face of our current understanding of the cosmos," said Dr. Arif Babul, University of Victoria. "Our standard model is that a bound group of galaxies like this should have a lot of dark matter. What does it mean that this one doesn't?"

In the Bullet Cluster, known as 1E 0657-56, the hot gas is slowed down during the collision but the galaxies and dark matter appear to continue on unimpeded. In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas.

Mahdavi and his colleagues have two possible explanations for their findings, both of which are uncomfortable for prevailing theories. The first option is that the galaxies were separated from the dark matter through a complex set of gravitational "slingshots." This explanation is problematic because computer simulations have not been able to produce slingshots that are nearly powerful enough to cause such a separation.

The second option is that dark matter is affected not only by gravity, but also by an as-yet-unknown interaction between dark matter particles. This exciting alternative would require new physics and could be difficult to reconcile with observations of other galaxies and galaxy clusters, such as the aforementioned Bullet Cluster.

In order to confirm and fully untangle the evidence for the Abell 520 dark matter core, the researchers have secured time for new data from Chandra plus the Hubble Space Telescope. With the additional observations, the team hopes to resolve the mystery surrounding this system.

SOURCE:SPACEFLIGHTNOW.COM

 

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New study on role of climate in Neanderthal extinction
   
 
   


Questions remain unresolved as to whether the Neanderthals died out because of competition with modern people or because of deteriorating climatic conditions. Although scientists have gained increased knowledge of past climate it has been difficult to pinpoint the climatic character at the time of the Neanderthal disappearance. A new study by an international team of researchers, published this week in the prestigious journal Nature, has developed a breakthrough approach to address this issue (Nature, September 13, 2007).



Fig.: Comparison of Neanderthal and modern human skeletons.

Image: (Photo: K. Mowbray, Reconstruction: G. Sawyer and B. Maley, Copyright: Ian Tattersall).


"Our findings suggest that there was no single climatic event that caused the extinction of the Neanderthals" says palaeoanthro-pologist Katerina Harvati. Only a controversial date for very late Neanderthal survival places their disappearance just before a major environmental shift. "Even in this case" continues Harvati "the role of climate would have been indirect, perhaps promoting competition with other human groups".

"There are three main limitations to understanding the role of climate in the Neanderthal extinction" explains palaeoecologist Chronis Tzedakis: uncertainty over the exact timing of the Neanderthal disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record. "Our novel method circumvents the last two problems" adds palaeoclimatologist Konrad Hughen. "We were therefore able to provide a much more accurate picture of the climatic background at the time of the Neanderthal disappearance". "More generally," continues Hughen "our approach offers the huge potential to unravel the role of climate in critical events of the recent fossil record as it can be applied to any radiocarbon date from any deposit".

The new method was applied by the researchers to three possible dates for the Neanderthal extinction obtained from Gorham’s cave, Gibraltar - a site thought to have been occupied by some of the latest surviving Neanderthals. The first two of these dates (~32 and ~28 thousand radiocarbon years ago) relate to conditions that are not distinct from the general climatic instability of the last glacial period. The much more controversial date of ~24 thousand radiocarbon years ago places the last Neanderthals just before a major environmental shift, with an expansion of ice sheets and onset of cold conditions in northern Europe. Gibraltar’s climate, however, remained relatively unaffected "perhaps as a result of warm water from the subtropical Atlantic entering the western Mediterranean" according to palaeoceanographer Isabel Cacho.

The study was conducted by Chronis Tzedakis (University of Leeds); Konrad Hughen (Woods Hole Oceanographic Institution); Isabel Cacho (University of Barcelona); Katerina Harvati (Max Planck Institute for Evolutionary Anthropology).

SOURCE:EUREKALERT.ORG
« Last Edit: 19/09/2007 22:34:47 by neilep »
 

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A Warm South Pole? Yes, on Neptune!
Summer season on Neptune creates escape route for methane



Neptune's 'Hot' South Pole (VISIR/VLT)


Thermal images of planet Neptune taken with VISIR on ESO's Very Large Telescope, obtained on 1 and 2 September 2006. These thermal images show a 'hot' south pole on Neptune. These warmer temperatures provide an avenue for methane to escape out of the deep atmosphere. Scientists say Neptune's south pole is 'hotter' than anywhere else on the planet by about 10 degrees Celsius. The average temperature on Neptune is about minus 200 degrees Celsius. The upper left image samples temperatures near the top of Neptune's troposphere (near 100 mbar pressure). The hottest temperatures are located at the lower part of the image at Neptune's south pole (see the graphic at the upper right). The lower two images, taken 6.3 hours apart, sample temperatures at higher altitudes in Neptune's stratosphere. They do show generally warmer temperatures near, but not at, the south pole. In addition they show a warm area which can be seen in the lower left image and rotated completely around the planet in the lower right image.

Credit: VLT/ESO/NASA/JPL/Paris Observatory
 

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Super stuff in here. Thanks to this thread, I now have a pletora of new screen wallpapers.
Planets with four parents? C[8D] [8D]L

Mom - where's that? Is that real?
Perhaps honey, perhaps.....
 ;D



Now I know they're not exactly 'last weeks' and if they're a really old hat for ya then I'll happily bazook this post..... just yell!


Cell on the move
Dr Aleksandar Ivetic, of Imperial College, London, won the British Heart Foundation picture of the year with this image of a migrating cell. The vivid colours come from the markers used to visualise the location of different cytoskeleton proteins essential for cell movement.
Reference url



Mysterious microbubble
Injected preparations of tiny ‘microbubbles’ can be used to enhance the contrast and distinguish different structures within the body during ultrasound diagnosis of heart disease. This image by Raniska Tente, of the University of Edinburgh, is a computer-enhanced microscope image of a microbubble, just 100 millionths of a metre in diameter.
Reference url



Heart muscle  
Heart muscle is made of different cell types that ‘talk’ to each other so the tissue can respond to changing conditions and efficiently pump blood round the body. This image by Patrizia Camelliti and Peter Kohl shows the microscopic architecture of heart muscle, showing the muscle in red closely associated with fibroblast cells in green.  Reference url



Diseased blood vessels
DNA microarray technology allows scientists to quickly analyse the activity of thousands of genes in a single tissue sample. Here, Marianna Papaspyridonos and David Greaves from Oxford University, have tested gene activity in white blood cells from diseased blood vessels. Each spot represents a single gene – the brightest are the most active. Reference url


A human heart - ART ! ;D

 
 




 

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Cassini is on the trail of a runaway mystery
NASA/JPL NEWS RELEASE
Posted: October 8, 2007

NASA scientists are on the trail of Iapetus' mysterious dark side, which seems to be home to a bizarre "runaway" process that is transporting vaporized water ice from the dark areas to the white areas of the Saturnian moon.


Cassini captures the first high-resolution glimpse of the bright
trailing hemisphere of Saturn's moon Iapetus in this false-color mosaic. This false-color
 mosaic shows the entire hemisphere of Iapetus. Credit: NASA/JPL/Space Science Institute

Download larger image version here

 
 
This "thermal segregation" model may explain many details of the moon's strange and dramatically two-toned appearance, which have been revealed exquisitely in images collected during a recent close flyby of Iapetus by NASA's Cassini spacecraft.

Infrared observations from the flyby confirm that the dark material is warm enough (approximately minus 230 degrees Fahrenheit or 127 Kelvin) for very slow release of water vapor from water ice, and this process is probably a major factor in determining the distinct brightness boundaries.

"The side of Iapetus that faces forward in its orbit around Saturn is being darkened by some mysterious process," said John Spencer, Cassini scientist with the composite infrared spectrometer team from the Southwest Research Institute, Boulder, Colo.

Using multiple instruments on Cassini, scientists are piecing together a complex story to explain the bright and dark faces of Iapetus. But yet to be fully understood is where the dark material is coming from. Is it native or from outside the moon? It has long been hypothesized that this material did not originate from within Iapetus, but instead was derived from other moons orbiting at a much greater distance from Saturn in a direction opposite to Iapetus.

Scientists are now converging on the notion that the darkening process in fact began in this manner, and that thermal effects subsequently enhanced the contrast to what we see today.

"It's interesting to ponder that a more than 30-year-old idea might still help explain the brightness difference on Iapetus," said Tilmann Denk, Cassini imaging scientist at the Free University in Berlin, Germany. "Dusty material spiraling in from outer moons hits Iapetus head-on, and causes the forward-facing side of Iapetus to look different than the rest of the moon."

Once the leading side is even slightly dark, thermal segregation can proceed rapidly. A dark surface will absorb more sunlight and warm up, explains Spencer, so the water ice on the surface evaporates. The water vapor then condenses on the nearest cold spot, which could be Iapetus's poles, and possibly bright, icy areas at lower latitudes on the side of the moon facing in the opposite direction of its orbit. So the dark stuff loses its surface ice and gets darker, and the bright stuff accumulates ice and gets brighter, in a runaway process.

Scientists say the result is that there are virtually no shades of gray on Iapetus. There is only white and very dark.

Ultraviolet data also show a non-ice component in the bright, white regions of Iapetus. Spectroscopic analysis will reveal whether the composition of the material on the dark hemisphere is the same as the dark material that is present within the bright terrain.

"The ultraviolet data tell us a lot about where the water ice is and where the non-water ice stuff is. At first glance, the two populations do not appear to be present in the pattern we expected, which is very interesting," said Amanda Hendrix, Cassini scientist on the ultraviolet imaging spectrograph team at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Because of the presence of very small craters that excavate the bright ice beneath, scientists also believe that the dark material is thin, a result consistent with previous Cassini radar results. But some local areas may be thicker. The dark material seems to lie on top of the bright region, consistent with the idea that it is a residual left behind by the sublimated water ice.

Some other mysteries are coming together. There are more data on the signature mountain ridge that gives Iapetus its "walnut" appearance. In some places it appears subdued. One big question that remains is why it does not go all the way around.

Was it partially destroyed after it formed, or did it never extend all the way around the moon? Scientists have ruled out that it is a youthful feature because it is pitted with craters, indicating it is old. And the ridge looks too solid and competent to be the result of an equatorial ring around the moon collapsing onto its surface. The ring theory cannot explain features that look like tectonic structures in the new high resolution images.

Over the next few months, scientists hope to learn more about Iapetus' mysteries.

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 mission for NASA's Science Mission Directorate, Washington, D.C.

SOURCE: SPACEFLIGHTNOW>COM
« Last Edit: 13/10/2007 15:20:51 by neilep »
 

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Uncovering The Veil Nebula




Source: Hubblesite.org

 

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Solar Telescope Reaches 120,000 Feet on Jumbo-Jet-Sized Balloon






Slender hoses, blown into arcs by the wind, partially fill the balloon
 with helium before launch. A large portion of the balloon is left unfilled so it can
expand as it ascends into the stratosphere, where air pressure is considerably lower.
 (Photo by Carlye Calvin, ©UCAR. News media terms of use*)
 

 

BOULDER—In a landmark test flight, the National Center for Atmospheric Research (NCAR) and a team of research partners this month successfully launched a solar telescope to an altitude of 120,000 feet, borne by a balloon larger than a Boeing 747 jumbo jet. The test clears the way for long-duration polar balloon flights beginning in 2009 that will capture unprecedented details of the Sun's surface.

"This unique research project will enable us to view features of the Sun that we've never seen before," says Michael Knölker, director of NCAR's High Altitude Observatory and a principal investigator on the project. "We hope to unlock important mysteries about the Sun's magnetic field structures, which at times can cause electromagnetic storms in our upper atmosphere and may have an impact on Earth's climate."

The project, known as Sunrise, is an international collaboration involving NCAR, NASA, Germany's Max Planck Institute for Solar System Research and Kiepenheuer Institute for Solar Physics, Spain's Astrophysics Institute of the Canary Islands, and the Swedish Space Corporation. Additional U.S. partners include the Lockheed Martin Corporation and the University of Chicago. Funding for NCAR's work on the project comes from NASA and from the National Science Foundation, which is NCAR's primary sponsor.

The project may usher in a new generation of balloon-borne scientific missions that cost less than sending instruments into space. Scientists also can test an instrument on a balloon before making a commitment to launch it on a rocket.

The balloon, with its gondola of scientific instruments, was launched successfully on the morning of October 3 from the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. It flew for about 10 hours, capturing stable images of the solar surface and additional data from the various instruments of the sophisticated payload. The gondola then separated from the balloon and descended with a parachute, landing safely in a field outside Dalhart, Texas.

"We were able to verify the workings of the entire system end to end," says David Elmore, an NCAR engineer who oversaw the test flight. "We can now move on to planning the first full-scale mission with confidence."

Observing the midnight Sun


The ultimate goal of the Sunrise project is to investigate the structure and dynamics of the Sun's magnetic fields. The fields fuel solar activity, including plasma storms that buffet Earth's outer atmosphere and affect sensitive telecommunications and power systems. The fields also cause variations in solar radiation, which may be significant factors in long-term changes in Earth's climate.

The Sunrise project is scheduled next for a multiday flight over the Arctic in the summer of 2009, launching from Kiruna, Sweden. By taking advantage of the midnight Sun, the telescope will be able to capture continuous images for a period of several days to as long as two weeks, possibly orbiting the Arctic. It may be launched later on another long-distance flight over the Arctic or the Antarctic.

At an altitude of 120,000 feet, the telescope will rise above most of the turbulence of the atmosphere and ultraviolet-absorbing water vapor and ozone. It will be able to view stable images in the ultraviolet range, which allow for higher resolution than can be obtained from Earth's surface.

The telescope will capture features on the solar surface as small as 30 kilometers across (about 19 miles), more than double the resolution achieved by any other instrument to date. This will enable scientists to examine structures on the Sun that are believed to be key to understanding the mechanisms driving solar activity. In addition, by observing the same area during an entire flight over high latitudes in summer, the telescope will enable scientists to continually witness changes in the magnetic fields without the interruption of night.




The Sun rises behind the silhouetted Sunrise telescope just
prior to launch on October 3.  (Photo by Carlye Calvin, ©UCAR. News media terms of use*)


 
A sharp focus from a twisting balloon


The Sunrise project has presented engineers with a number of extraordinary challenges. The balloon is designed to carry 6,000 pounds of equipment, including a 1-meter (39-inch) solar telescope, additional observing instruments, communications equipment, computers and disk drives, solar panels, and roll cages and crush pads to protect the payload on landing. The equipment must be able to withstand dramatic changes in temperature, and the steel and aluminum gondola cannot vibrate in ways that could interfere with the operation of the telescope.

One of the most difficult aspects of the engineering work was to design the gondola in such a way that the telescope in flight would remain focused on a specific and relatively tiny area of the Sun, even while twisting on a soaring balloon for a week or longer during the full-scale research missions. To accomplish this, the gondola includes both a torque motor drive to keep the gondola and telescope in the correct orientation and a precision guiding and compensation system to constantly correct the telescope's aim.

In addition to the telescope, the gondola on its full-scale research missions will carry a polarimetric spectrograph that will measure wavelengths in the Sun's electromagnetic spectrum and enable scientists to make inferences about its magnetic fields. Another instrument, known as an imaging magnetograph, will provide two-dimensional magnetic field maps.

Because the gondola is designed to withstand considerable force when it lands, the instruments can be launched on repeated missions.

"This is a very economical way of rising above the atmosphere and capturing images that cannot be captured from Earth," Knölker says. "What we are doing is laying the groundwork for the next generation of space flights."

SOURCE: The University Corporation For Atmospheric Research
http://www.ucar.edu/news/releases/2007/sunrise.shtml

 
« Last Edit: 25/10/2007 00:43:12 by neilep »
 

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A Galaxy for Science and Research
European Commissioner captures stunning image of twisted spiral galaxy with ESO's VLT

During his visit to ESO's Very Large Telescope at Paranal, the European Commissioner for Science and Research, Janez Potočnik, participated in an observing sequence and took images of a beautiful spiral galaxy.



ESO PR Photo 49/07
Twisted Spiral Galaxy NGC 134


The visit took place on 27 October and the Commissioner observed with one of the FORS instruments on Antu, the first 8.2-m Unit Telescope of the VLT.

"Two hours bus ride from the nearest town, Antofagasta, in the middle of nowhere and at 2 600 m altitude, rises a state of the art astronomical observatory at which scientists from across Europe venture to exploit some of the most advanced technologies and sophisticated techniques available within astronomy. One of the facilities is the VLT, the Very Large Telescope, with which, together with the other telescopes, scientists can study objects at the far edge of the Universe," wrote Potočnik on his blog.

Known until now as a simple number in a catalogue, NGC 134, the 'Island in the Universe' that was observed by the Commissioner is replete with remarkable attributes, and the VLT has clapped its eyes on them. Just like our own Galaxy, NGC 134 is a barred spiral with its spiral arms loosely wrapped around a bright, bar-shaped central region.

One feature that stands out is its warped disc. While a galaxy's disc is often pictured as a flat structure of gas and stars surrounding the galaxy's centre, a warped disc is a structure that, when viewed sideways, resembles a bent record album left out too long in the burning Sun.

Warps are actually not atypical. More than half of the spiral galaxies do show warps one way or another, and our own Milky Way also has a small warp.

Many theories exist to explain warps. One possibility is that warps are the aftermath of interactions or collisions between galaxies. These can also produce tails of material being pulled out from the galaxy. The VLT image reveals that NGC 134 also appears to have a tail of gas stripped from the top edge of the disc.

So did NGC 134 have a striking encounter with another galaxy in the past? Or is some other galaxy out there exerting a gravitational pull on it? This is a riddle astronomers need to solve.

The superb VLT image also shows that the galaxy has its fair share of ionised hydrogen regions (HII regions) lounging along its spiral arms. Seen in the image as red features, these are glowing clouds of hot gas in which stars are forming. The galaxy also shows prominent dark lanes of dust across the disc, obscuring part of the galaxy's starlight.

Studying galaxies like NGC 134 is an excellent way to learn more about our own Galaxy.

NGC 134 was discovered by Sir John Herschel at the Cape of Good Hope and is located in the Sculptor southern constellation. The galaxy is located about 60 million light-years away - when the light that was captured by the VLT originally left the galaxy, a dramatic episode of mass extinction had led to the disappearance of dinosaurs on Earth, paving the way for the appearance of mammals and later specifically of humans, who have built unique high-tech installations in the Atacama desert to satisfy their curiosity about the workings of the Universe. Still, NGC 134 is not very far away, by cosmological standards. It is the dominant member of a small group of galaxies that belongs to the Virgo or Local Supercluster and is one of the 200 brightest galaxies in our skies.

SOURCE:www.eso.org
 

the1andonlydjt

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I just want to say Thank You for all of the good pictures.  I've enjoyed looking at them!
 

Offline ukmicky

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Welcome to the forum and thankyou for your kind comments but i feel Neil is the one who deserves your praise the most.
 

Offline Alandriel

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Neil likes the really biiiiiiiiiiiiig things - I get just as much kick out of the really tiiiiiiiiiiiny things

minature wonders  ;D


Porpita porpita, Blue button (jellyfish relative) - not one organism but many joined at the gas-filled hub that keeps the colony afloat. Each tentacle has a specialized role in the cooperative: catching prey, digesting or reproducing. The pigment blocks UV rays.
Chondrophore on Wikipedia



Clio pyramidata is a pteropod - a swimming snail - with a shell made out of aragon and was one of the first zooplankton species ever to have its genes sequenced at sea.



Baby octopus



Another jelly - Small planktonic jellyfish with bright green-fluorescent tentacles. The red fluorescence in the middle of the jellyfish comes from chlorophyll in the ingested algae. Image curtesy of Mikhail Matz.




 

Offline JimBob

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Hi

I think you mean "made of aragonite" not made of a part of Catalonia.

 [:I]
 

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