[neilep]

Hubble images some of galaxy's dimmest stars
RICE UNIVERSITY NEWS RELEASE
Posted: August 17, 2006

Using the Hubble Space Telescope, astronomers have imaged some of
 the galaxy's oldest and dimmest stars, offering a rare experimental
 glimpse of two mysterious star types tiny, slow burners less than
one-tenth the size of our sun and once giant stars that still glow
more than 10 billion years after their deaths.


 


Looking like glittering jewels, the stars in this
Hubble Space Telescope image at left are part of the ancient
globular star cluster NGC 6397. The image at lower right shows the
faintest red dwarf star (the red dot within the red circle) spied by
 Hubble. The image at upper right pinpoints one of the dim white
dwarfs (the blue dot within the blue circle) seen by Hubble. Credit:
NASA, ESA, and H. Richer (University of British Columbia)


The research appears in this week's issue of the journal Science.

"This project pushed the limits of what even Hubble can do," said study co-author Jay Anderson, a research scientist at Rice University. "These stars can't be reliably detected in a single image. You have to combine a large number of images to find them."

In total, the research team trained Hubble's cameras on the same patch of sky for more than 75 hours, gathering 378 overlapping images. The target was a region of space containing about 1 percent of the globular cluster NGC 6397 a collection of stars that formed early in our galaxy's history.

"When we look at random stars in the sky they have a variety of ages," Anderson said. "Globular clusters offer unique opportunities for astronomers to study a population of stars that are all the same age. All the stars we see in clusters are ancient, because they were created when the galaxy was forming. They're fossils from the galaxy's earliest days."

There are about 150 globular clusters in our galaxy, and most contain between 100,000 and 1 million stars. While most of the galaxy's stars including our own sun orbit the galactic center in the plane of the galaxy, globular clusters predate the flattening of the Milky Way, so they're scattered in a more spherical distribution.

NGC 6397 is one of the nearest clusters to Earth, located just 8,500 light years away. But even at this relatively close astronomical distance, the light from NGC 6397's faintest stars is easily lost in the glare from its brightest stars.

To survey the dimmest objects, Anderson and colleagues relied on computers. Anderson, whose specialty is writing programs to sift through astronomical data, spent months writing and refining software that could examine each Hubble image, pixel by pixel, and find the faintest stars.

The two types of object imaged represent the heavy end and the light end of the stellar mass spectrum.

A star's destiny is determined by its mass. There's a minimum mass that a star must have in order to burn hydrogen, and objects below that threshold cool rapidly and fade away. From the NGC 6397 survey, Anderson and his colleagues identified the smallest visible stars yet seen in a globular cluster, stars less than one-tenth the mass of Earth's sun. This is very near the predicted theoretical threshold, and Anderson said data from the survey will be helpful for verifying and refining theories about the structure and evolution of low-mass stars.

On the other end of the stellar mass spectrum are stars that are significantly larger than the sun. Stars about eight times the mass of the sun burn quickly and die in spectacular planetary nebulae, explosions that spew much of the star's material into space. Upon their final collapse, these stars become white dwarfs, extremely dense objects that radiate heat for billions of years as they slowly fade into darkness. Anderson said that while the brightest and therefore youngest white dwarfs have been seen in many clusters, the new survey yielded the first images of the faintest and oldest white dwarfs in an ancient cluster. The brightness of the white dwarfs at this end of the scale can help astronomers find out how long the stars have been cooling. From that, they can better determine the age of the cluster, which in turn can be used to narrow estimates of the lower limit of the age of the universe.

SOURCE: spaceflightnow.com

Men are the same as women, just inside out !

[neilep]

Mystery of Quintuplet stars in Milky Way solved
ROCHESTER INSTITUTE OF TECHNOLOGY NEWS RELEASE
Posted: August 17, 2006

For the first time, scientists have identified the cluster of Quintuplet stars in the Milky Way's galactic center, next to the super massive black hole, as massive binary stars nearing the end of their life cycle, solving a mystery that had dogged astronomers for more than 15 years.




A Yin and Yang in the Galactic Center. High-resolution infrared
images of the dusty pinwheel nebulae are shown inset overlaid on a
Hubble Space Telescope image of the Quintuplet cluster. Each of the
five bright red stars is now thought to be a pinwheel nebula.
Credit: Peter Tuthill (Sydney U.), Keck Observatory, Donald Figer

(RIT).
 
 
The nature of the stars was not entirely clear until now. In a paper published in the Aug. 18 issue of Science, co-authors Peter Tuthill of the University of Sydney and Donald Figer of Rochester Institute of Technology show that the Quintuplet cluster consists of young massive binary stars that produce large amounts of dust. Their data reveal that five bright red stars are nearing the end of their "short" lives of approximately 5 million years. These quickly evolving stars burn fast and bright, but die younger than fainter stars, which live for billions of years. The study captures the Quintuplet stars just before disintegrating in supernovae explosions.

Using advanced imaging techniques on the world's biggest telescope at the W.M. Keck Observatory in Hawaii, the scientists captured the stars at the highest attainable resolution for the instrument, far exceeding the capability of the Hubble Space Telescope, which imaged the cluster a decade ago. The extra-resolution gives scientists a new glimpse of the dust plumes surrounding the stars and the swirling spirals Tuthill likened to pinwheels when he identified the first one in 1999 elsewhere in the galaxy.

"Only a few pinwheels are known in the galaxy," Figer says. "The point is, we've found five all next to each other in the same cluster. No one has seen anything like this before."

According to Figer, the swirling dust in pinwheel stars is key to the presence of the most evolved massive stars and points to the presence of pairs of stars. The geometry of the plume allows scientists to measure the properties of the binary stars, including the orbital period and distance.

"The only way that pinwheels can form is if they have two stars, swirling around each other. The stars are so close that their winds collide, forming dust in a spiral shape, just like water sprayed from a garden hose of a twirling sprinkler," Figer says. "A single star wouldn't be able to produce the dust and wouldn't have the spiral outflow."

An earlier study by Figer in 1996 claimed the Quintuplet cluster consists of evolved massive stars that produce dust. Figer's research could not be confirmed until now with the use of the Keck telescope.

"If you want to understand star formation, you have to understand if they are forming alone or if they have partners," Figer says. "The answer gives us a clue as to whether stars form alone or with companions."


Source: spaceflightnow.com








Men are the same as women, just inside out !

[neilep]

Eternal life of stardust portrayed in Spitzer image
UNIVERSITY OF ARIZONA NEWS RELEASE


This vibrant image from NASA's Spitzer Space Telescope
shows the Large Magellanic Cloud, a satellite galaxy to our own
Milky Way galaxy. Credit: NASA/JPL-Caltech/M. Meixner (STScI) & the
 SAGE Legacy Team

Download larger image version here

 
 
Astronomers have combined hundreds of thousands of Spitzer Space Telescope images into a map of the whole Large Magellanic Cloud. They see features throughout the galaxy in such sharp detail that they can count newly formed stars, determine how much dust old stars are pumping into the galaxy and, for the first time, to sensitively map the rate at which stars are forming across an entire galaxy.

"We can use this amazing map to really start to understand in detail how a galaxy evolves," said Karl Gordon of the University of Arizona Steward Observatory. Gordon heads the UA group who processed 600,000 images that Spitzer's Multiband Imaging Photometer (MIPS) took of the Large Magellanic Cloud.

The Large Magellanic Cloud, a satellite galaxy of our Milky Way about 160,000 light years away, is an ideal astrophysical laboratory for studying the lifecycle of galaxies.

Using Spitzer's unprecedented sensitivity across a spectrum of infrared wavelengths, "We now can study some details in another galaxy that so far we've been able to study only in our own galaxy," Gordon said.

Spitzer scientists combined some of the MIPS images with others taken by the Infrared Array Camera (IRAC), a Spitzer instrument that takes images at shorter infrared wavelengths than MIPS does. The result is a composite picture of 300,000 images of the Large Magellanic Cloud, a picture that shows everything from hot stars to cold dust between the stars, or the interstellar medium.

"What's exciting and significant is that our images go really deep in the galaxy, deep enough to get a life cycle of the interstellar medium, a life cycle of dust. We see young stars which consume dust as they form in dusty molecular clouds and old stars which are ejecting dust back into the interstellar medium.

"We can now test sophisticated theories about how stars form, how they evolve, what the different populations are, and how important they are in a global galaxy environment," Gordon said. "One of the strengths of this is not just that we've measured a small piece of the galaxy, but we've measured almost the entire galaxy in deep, sharp detail."

The survey of the Large Magellanic Cloud is among 19 key "Legacy" projects undertaken by NASA's Spitzer Space Telescope, which was launched August 2003. The project is headed by Margaret Meixner of the Space Telescope Science Institute in Baltimore. Others from the UA Steward Observatory who are reporting this research in the Astronomical Journal are Charles W. Engelbracht, Bi-Qing For, Karl Misselt, Jason Harris, Douglas Kelly, Pablo Perez-Gonzalez and Dennis Zaritsky.

SOURCE: SPACEFLIGHTNOW.COM





Men are the same as women, just inside out !

[neilep]

Incredible cliffs of Dione
CASSINI PHOTO RELEASE




Credit: NASA/JPL/Space Science Institute
Download larger image version here
 
 
This splendid view showcases Dione's tortured complex of bright cliffs. At lower right is the feature called Cassandra, exhibiting linear rays extending in multiple directions.

The trailing hemisphere of Dione (1,126 kilometers, or 700 miles across) is seen here. North is up.

The image was taken in polarized green light with the Cassini spacecraft narrow-angle camera at a distance of approximately 263,000 kilometers (163,000 miles) from Dione. Image scale is 2 kilometers (1 mile) per pixel.

SOURCE:SPACEFLIGHTNOW.COM

Men are the same as women, just inside out !

[neilep]

Space station streaks over Atlantis
SPACEFLIGHT NOW
Posted: September 5, 2006

As space shuttle Atlantis stands bathed in powerful flood lights at launch pad 39B on the evening before blastoff, its destination -- the International Space Station -- soars overhead as photographed in this time-lapse image from the Kennedy Space Center press site.


Credit: Ben Cooper/Spaceflight Now
 

SOURCE: SPACEFLIGHTNOW>COM





Men are the same as women, just inside out !

[neilep]

Planet or failed star? Hubble finds strange object
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: September 7, 2006

Astronomers using NASA's Hubble Space Telescope have photographed one of the smallest objects ever seen around a normal star beyond our Sun. Weighing in at 12 times the mass of Jupiter, the object is small enough to be a planet. The conundrum is that it's also large enough to be a brown dwarf, a failed star.



This Hubble image shows the brown dwarf candidate,
called CHXR 73 B, as the bright spot at lower right. It orbits a red
 dwarf star, dubbed CHXR 73, which is a third less massive than the
Sun. Credit: NASA, ESA and K. Luhman (Penn State University)

Download larger image version here
 
 
The Hubble observation of the diminutive companion to the low-mass red dwarf star CHXR 73 is a dramatic reminder that astronomers do not have a consensus in deciding which objects orbiting other stars are truly planets -- even though they have at last agreed on how they will apply the definition of "planet" to objects inside our solar system.

Kevin Luhman of Penn State University in University Park, Pa., leader of the team that found the object, called CHXR 73 B, is casting his vote for a brown dwarf. "New, more sensitive telescopes are finding smaller and smaller objects of planetary-mass size," said Luhman. "These discoveries have prompted astronomers to ask the question, are planetary-mass companions always planets?"

Some astronomers suggest that an extrasolar object's mass determines whether it is a planet. Luhman and others advocate that an object is only a planet if it formed from the disk of gas and dust that commonly encircles a newborn star. Our solar system planets formed 4.6 billion years ago out of a dust disk around our Sun.

Brown dwarfs, by contrast, form just like stars: from the gravitational collapse of large, diffuse clouds of hydrogen gas. Unlike stars, brown dwarfs do not have quite enough mass to ignite hydrogen fusion reactions in their cores, which power stars such as our Sun.

CHXR 73 B is 19.5 billion miles from its red dwarf sun. That's roughly 200 times farther than Earth is from our Sun. At 2 million years old, the star is very young when compared with our middle-aged 4.6-billion-year-old Sun.

"The object is so far away from its star that it is unlikely to have formed in a circumstellar disk," Luhman explained. Disks around low-mass stars are about 5 to 10 billion miles in diameter. There isn't enough material at that distance from the red dwarf to create a planet. Theoretical models show that giant planets like Jupiter form no more than about 3 billion miles from their stars.



This is an artist's concept of the red dwarf star CHXR
73 (upper left) and its companion CHXR 73 B in the foreground (lower
right) weighing in at 12 Jupiter masses. Credit: NASA, ESA and G.
Bacon (STScI)

Download larger image version here
 
Hubble's Advanced Camera for Surveys discovered the object while conducting a survey of free-floating brown dwarfs. Astronomers have found hundreds of brown dwarfs in our galaxy since the first brown dwarfs were spied about a decade ago. Most of them are floating through space and not orbiting stars.

"It is important to study young star systems to understand how small bodies formed. Young brown dwarfs are brighter than older, cooler brown dwarfs. This allows them to be seen even at lower masses, where older dwarfs would still be undetectable," said team member John Wilson of the University of Virginia in Charlottesville.

One way to further settle the uncertainty would be if a disk of dust could be observed around CHXR 73's companion. Like stars, brown dwarfs have circumstellar disks, too. They would be no more than about 2 billion miles in diameter.

NASA's Spitzer Space Telescope has detected disks around several free-floating brown dwarfs. But CHXR 73 B is too close to its star for Spitzer to detect the disk. So astronomers will have to wait for the launch of the James Webb Space Telescope in 2013 to determine if this companion has a disk. The Webb telescope will combine Hubble's sharpness, which is needed for detecting close companions, and Spitzer's infrared sensitivity, which is necessary for seeing cool, dusty disks.

The team's result will appear in the Sept. 20 issue of the Astrophysical Journal.


SOURCE: SPACEFLIGHTNOW.COM





Men are the same as women, just inside out !

[neilep]

Earliest New World Writing Discovered

 A heap of debris taken from a quarry in Veracruz, Mexico has yielded a stone block inscribed with what appears to be the oldest writing ever found in the Americas. Numerous symbols are carved across the block in rows. Experts say the block dates back almost 3,000 years, and was created by people from the Olmec civilization. The Olmec were an early central American people who rose to prominence before the heyday of the Maya.

It is a once-in-a-lifetime discovery, says Stephen Houston, an archeologist at Brown University.

The inscriptions are hieroglyphics -- 62 small drawings in rows, with some of the signs repeated up to four times.

"It's not just a set of symbols that might be placed together the way you might see, let's say, on medieval French or English painting," Houston says. "Rather, they are arranged in a sequence that is meant to reflect a language with grammatical elements and with a word order that makes sense."

There are 28 different glyphs -- as archeologists call the signs for short. Some look like vegetables. One looks like a sharp awl or pick. Some symbols are repeated, such as a symbol that looks like an insect. Houston suspects that one symbol might be some sort of punctuation. Some sequences of symbols are separated from the rest, in what look like poetic couplets.

Not all of these symbols are unfamiliar to archeologists. Mary Pohl at Florida State University is an expert on the Olmec. She's analyzed Olmec symbols on jewelry and a cylindrical seal that dates almost as far back as the inscribed tablet. She says a few of the symbols are clearly written versions of carved stone objects, like an ear of corn, previously found at Olmec archeological sites.

"One sign looks actually like a corn cob with silk coming out the top," Pohl says. Other signs are unique, she says, and never before seen, like one of an insect.

Pohl says these objects -- and thus probably the writing -- had a special value in rituals.

"We see that the writing is very closely connected with ritual and the early religious beliefs, because they are taking the ritual carvings and putting them into glyphs and making writing out of them," Pohl says. "And all of this is occurring in the context of the emergence of early kings and the development of a centralized power and stratified society."

The tablet and inscriptions are described in the journal Science. Its date is based on other artifacts found nearby, and may need further confirmation.

Houston and scientists from Mexico who first identified the text say they have no idea what it actually says. With no previous text to work from, deciphering it will be difficult.

What's needed are more texts for comparison. Archeologists say there are a lot of Olmec sites in Mexico that are still unexplored, and any one could hold the key to reading the oldest known language in the Americas.


Front view of a stone block recently discovered in
Veracruz, Mexico. It's inscribed with 28 different signs, some of
them repeated.  Science © 2006



A recreation of the symbols and their placement on the
Veracruz stone block.  Science © 2006


A previously discovered cylinder seal from San Andres,
Tabasco, Mexico, showing glyphs also created by the Olmec
civilization. The writings are estimated to date from 650 B.C.

 

SOURCE:NPR.ORG



Men are the same as women, just inside out !

[neilep]

Meet the Earliest Baby Girl ever Discovered!

Discovery of an Australopithecus afarensis child will help to answer important questions concerning human evolution
   
   
   


3.3 million years ago, a three year old girl died in present day Ethiopia, in an area called Dikika. Though a baby, she provides researchers with a unique account of our past, as would a grandmother. Her completeness, antiquity, and age at death combine make this find unprecedented in the history of paleoanthropology and open many new research avenues to investigate into the infancy of early human ancestors. The extraordinary discovery reported this week in the scientific journal Nature, was found in north-eastern Ethiopia, by a paleoanthropological research team led by Dr. Zeresenay Alemseged of the Max Planck Institute in Leipzig, Germany. The scientific significance of the new find is multi-fold, contributing substantially to our comprehension of the morphology, body plan, behaviour, movement and developmental patterns of our early ancestors. After full cleaning and preparation of the fossil it will be possible to reconstruct, for the first time, much of an entire body of a 3 year-old Australopithecus afarensis child, which will resolve many pending questions regarding early human evolution.



Fig. 1: The skull of the Australopithecus afarensis child.

Image: National Museum of Ethiopia, Addis Ababa


The new find consists of a skeleton of the earliest and most complete juvenile human ancestor ever found that lived 150,000 years before Lucy. She was only three years old when she died and belongs to Australopithecus afarensis (the Lucy species) and was found in an area called Dikika, in Ethiopia, by a paleoanthropological team, the DRP (Dikika Research Project) led by Dr. Zeresenay Alesmeged of the Max Planck Institute. The DRP is an international and multidisciplinary project including several researchers with diverse areas of expertise, and about 40 assistants conducting field research in Ethiopia every year. The first piece of the baby was found on December 10th, 2000, but recovering the partial skeleton required intensive searching and sifting over four successive field seasons




 Some of the postcranial (the skeleton other than the head) elements of the Dikika skeleton.

Image: National Museum of Ethiopia, Addis Ababa


SOURCE: EUREKAALERT.ORG

Men are the same as women, just inside out !

[Hadrian]

You may like the picture I posted in this topic.
http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=5360


What you do speaks so loudly that I cannot hear what you say.

[neilep]

Hundreds of young galaxies found in early universe
SPACE TELESCOPE SCIENCE INSTITUTE NEWS RELEASE
Posted: September 24, 2006

Astronomers analyzing two of the deepest views of the cosmos made with NASA's Hubble Space Telescope have uncovered a gold mine of galaxies, more than 500 that existed less than a billion years after the Big Bang. These galaxies thrived when the cosmos was less than 7 percent of its present age of 13.7 billion years. This sample represents the most comprehensive compilation of galaxies in the early universe, researchers said.





The discovery is scientifically invaluable for understanding the origin of galaxies, considering that just a decade ago early galaxy formation was largely uncharted territory. Astronomers had not seen even one galaxy that existed when the universe was a billion years old, so finding 500 in a Hubble survey is a significant leap forward for cosmologists.

The galaxies unveiled by Hubble are smaller than today's giant galaxies and very bluish in color, indicating they are ablaze with star birth. The images appear red because of the galaxies' tremendous distance from Earth. The blue light from their young stars took nearly 13 billion years to arrive at Earth. During the journey, the blue light was shifted to red light due to the expansion of space.

"Finding so many of these dwarf galaxies, but so few bright ones, is evidence for galaxies building up from small pieces -- merging together as predicted by the hierarchical theory of galaxy formation," said astronomer Rychard Bouwens of the University of California, Santa Cruz, who led the Hubble study.

SOURCE: SPACEFLIGHTNOW.COM


Men are the same as women, just inside out !

[neilep]

Opportunity rover arrives at dramatic vista
NASA NEWS RELEASE
Posted: September 27, 2006

NASA's Mars Rover Opportunity has arrived at the rim of a crater approximately five times wider than a previous stadium-sized one it studied for half a year.


Credit: NASA/JPL-Caltech
Download larger image version here
 
 
Initial images from the rover's first overlook after a 21-month journey to "Victoria Crater" show rugged walls with layers of exposed rock and a floor blanketed with dunes. The far wall is approximately one-half mile from the rover.

"This is a geologist's dream come true," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for NASA's twin rovers Opportunity and Spirit. "Those layers of rock, if we can get to them, will tell us new stories about the environmental conditions long ago. We especially want to learn whether the wet era that we found recorded in the rocks closer to the landing site extended farther back in time. The way to find that out is to go deeper, and Victoria may let us do that."

Opportunity has been exploring Mars since January 2004, more than 10 times longer than its original prime mission of three months. It has driven more than 5.7 miles. Most of that was to get from "Endurance" crater to Victoria, across a flat plain pocked with smaller craters and strewn with sand ripples. Frequent stops to examine intriguing rocks interrupted the journey, and one large sand ripple kept the rover trapped for more than five weeks

SOURCE : SPACEFLIHTNOW.COM


Men are the same as women, just inside out !

[neilep]

Hubble finds extrasolar planets far across galaxy
NASA NEWS RELEASE

NASA's Hubble Space Telescope has discovered 16 extrasolar planet candidates orbiting a variety of distant stars in the central region of our Milky Way galaxy.

The planet bonanza was uncovered during a Hubble survey called the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). Hubble looked farther than has ever successfully been searched before for extrasolar planets. Hubble peered at 180,000 stars in the crowded central bulge of our galaxy 26,000 light-years away. That is one-quarter the diameter of the Milky Way's spiral disk. The results will appear in the Oct. 5 issue of the journal Nature.


This illustration presents a purely speculative view of what such a
"hot Jupiter" might look like. Credit: NASA, ESA, and A. Schaller (for STScI)


This tally is consistent with the number of planets expected to be uncovered from such a distant survey, based on previous exoplanet detections made in our local solar neighborhood. Hubble's narrow view covered a swath of sky no bigger in angular size than two percent the area of the full moon. When extrapolated to the entire galaxy, Hubble's data provides strong evidence for the existence of approximately six billion Jupiter-sized planets in the Milky Way.

Five of the newly discovered planets represent a new extreme type of planet not found in any nearby searches. Dubbed Ultra-Short-Period Planets (USPPs), these worlds whirl around their stars in less than one Earth day.

"Discovering the very short-period planets was a big surprise," said team leader Kailash Sahu of the Space Telescope Science Institute, Baltimore. "Our discovery also gives very strong evidence that planets are as abundant in other parts of the galaxy as they are in our solar neighborhood."

Hubble could not directly view the 16 newly found planet candidates. Astronomers used Hubble's Advanced Camera for Surveys to search for planets by measuring the slight dimming of a star due to the passage of a planet in front of it, an event called a transit. The planet would have to be about the size of Jupiter to block enough starlight, about one to 10 percent, to be measurable by Hubble.

The planets are called candidates, because astronomers could only obtain follow-up mass measurements for two of them due to the distance and faintness of these systems. Following an exhaustive analysis, the team ruled out alternative explanations such as a grazing transit by a stellar companion that could mimic the predicted signature of a true planet. The finding could more than double the number of planets spied with the transit technique to date.

There is a tendency for the planet candidates to revolve around stars more abundant in elements heavier than hydrogen and helium, such as carbon. This supports theories that stars rich in heavy elements have the necessary ingredients to form planets.

The planet candidate with the shortest orbital period, named SWEEPS-10, swings around its star in 10 hours. Located only 740,000 miles from its star, the planet is among the hottest ever detected. It has an estimated temperature of approximately 3,000 degrees Fahrenheit.

"This star-hugging planet must be at least 1.6 times the mass of Jupiter, otherwise the star's gravitational muscle would pull it apart," said SWEEPS team member Mario Livio. "The star's low temperature allows the planet to survive so near to the star."

"Ultra-Short-Period Planets seem to occur preferentially around normal red dwarf stars that are smaller and cooler than our sun," Sahu explained. "The apparent absence of USPPs around sun-like stars in our local neighborhood indicates that they might have evaporated away when they migrated too close to a hotter star."


This is an image of one-half of the Hubble Space Telescope field of view in
 the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). The green
circles identify 9 stars that are orbited by planets with periods of a few days.
 The bottom frame identifies one of two stars in the field where astronomers
were able to spectroscopically measure the star's back-and-forth wobble due to
the pull of the planet. Credit: NASA, ESA, K. Sahu (STScI) and the SWEEPS Science Team

There is an alternative reason why Jupiter-like planets around cooler stars may migrate in closer to the star than such planets around hotter stars. The circumstellar disk of gas and dust out of which they formed extends in closer to a cooler star. Since the discovery of the first "hot Jupiter" around another star in 1995, astronomers have realized this unusual type of massive planet must have spiraled in close to its parent star from a more distant location where it must have formed. The inner edge of a circumstellar disk halts the migration.

Planetary transits occur only when the planet's orbit is viewed nearly edge-on. However, only about 10 percent of hot Jupiters have edge-on orbits that allow the planet to be observed transiting a star. To be successful, transit surveys must view a large number of stars at once. The SWEEPS transit survey covered a rich field of stars in the Sagittarius Window.

The term "window" implies a clear view into the galactic center, but much of the galactic plane is obscured by dust. Hubble monitored 180,000 stars for periodic, brief dimming in a star's brightness. The star field was observed over a continuous seven-day period Feb. 23-29, 2004.

To ensure the dimming was caused by an object orbiting a star, the team used Hubble to detect from two to 15 consecutive transits for each of the16 planet candidates. Two stars in the field are bright enough that the SWEEPS team could make an independent confirmation of a planet's presence by spectroscopically measuring a slight wobble in the star's motion due to the gravitational pull of an unseen companion. They used the European Southern Observatory's Very Large Telescope, located on Mount Paranal in Chile, to measure a slight wobble in the star.

One of the planetary candidates has a mass below the detection limit of 3.8 Jupiter masses. The other candidate is 9.7 Jupiter masses, which is below the minimum mass of 13 Jupiter masses for a brown dwarf. A brown dwarf is an object that forms like a star but does not have enough mass to shine by nuclear fusion.

Since the stars are so faint and the field of view is so densely packed with stars, measuring the slight wobble in the star's motion using spectroscopy to confirm most of the planet candidates is not feasible. Future telescopes such as NASA's James Webb Space Telescope will provide the needed sensitivity to confirm most of the planet candidates.

The Hubble SWEEPS program is an important proof-of-concept for NASA's future Kepler Mission, scheduled for launch in 2008. The Kepler observatory will continuously monitor a region of the Milky Way galaxy to detect transiting planets around mostly distant stars. Kepler will be sensitive enough to detect possibly hundreds of Earth-size planet candidates in or near the habitable zone, the distance from a star where liquid water could feasibly exist on a planet's surface.

SOURCE: SPACEFLIGHTNOW.COM

[neilep]

Spitzer peels back layers of star's explosion
NASA/JPL NEWS RELEASE
Posted: October 26, 2006

Astronomers using NASA's infrared Spitzer Space Telescope have discovered that an exploded star, named Cassiopeia A, blew up in a somewhat orderly fashion, retaining much of its original onion-like layering.


 [ Invalid Attachment ]
This image from Spitzer shows the scattered remains of
 an exploded star named Cassiopeia A. In this false-color
 image, the faint, blue glow surrounding the dead star is
material that was energized by a shock wave, called the
 forward shock, which was created when the star blew up.
 The forward shock is now located at the outer edge of
the blue glow. Stars are also seen in blue. Green, yellow
and red primarily represent material that was ejected in
the explosion and heated by a slower shock wave, called the
 reverse shock wave. Credit: NASA/JPL-Caltech
Download larger image version http://photojournal.jpl.nasa.gov/jpeg/PIA01903.jpg
 
 
"Spitzer has essentially found key missing pieces of the Cassiopeia A puzzle," said Jessica Ennis of the University of Minnesota, Minneapolis, lead author of a paper to appear in the Nov. 20 issue of the Astrophysical Journal.

"We've found new bits of the 'onion' layers that had not been seen before," said Dr. Lawrence Rudnick, also of the University of Minnesota, and principal investigator of the research. "This tells us that the star's explosion was not chaotic enough to stir its remains into one big pile of mush."

Cassiopeia A, or Cas A for short, is what is known as a supernova remnant. The original star, about 15 to 20 times more massive than our sun, died in a cataclysmic "supernova" explosion relatively recently in our own Milky Way galaxy. Like all mature massive stars, the Cas A star was once neat and tidy, consisting of concentric shells made up of various elements. The star's outer skin consisted of lighter elements, such as hydrogen; its middle layers were lined with heavier elements like neon; and its core was stacked with the heaviest elements, such as iron.

Until now, scientists were not exactly sure what happened to the Cas A star when it ripped apart. One possibility is that the star exploded in a more or less uniform fashion, flinging its layers out in successive order. If this were the case, then those layers should be preserved in the expanding debris. Previous observations revealed portions of some of these layers, but there were mysterious gaps.

Spitzer was able to solve the riddle. It turns out that parts of the Cas A star had not been shot out as fast as others when the star exploded. Imagine an onion blasting apart with some layered chunks cracking off and zooming away, and other chunks from a different part of the onion shooting off at slightly slower speeds.

"Now we can better reconstruct how the star exploded," said Dr. William Reach of NASA's Spitzer Science Center, Pasadena, Calif. "It seems that most of the star's original layers flew outward in successive order, but at different average speeds depending on where they started."

How did Spitzer find the missing puzzle pieces? As the star's layers whiz outward, they are ramming, one by one, into a shock wave from the explosion and heating up. Material that hit the shock wave sooner has had more time to heat up to temperatures that radiate X-ray and visible light. Material that is just now hitting the shock wave is cooler and glowing with infrared light. Consequently, previous X-ray and visible-light observations identified hot, deep-layer material that had been flung out quickly, but not the cooler missing chunks that lagged behind. Spitzer's infrared detectors were able to find the missing chunks ­ gas and dust consisting of the middle-layer elements neon, oxygen and aluminum.

Cassiopeia A is the ideal target for studying the anatomy of a supernova explosion. Because it is young and relatively close to our solar system, it is undergoing its final death throes right in front of the watchful eyes of various telescopes. In a few hundred years or so, Cas A's scattered remains will have completely mixed together, forever erasing important clues about how the star lived and died.


SOURCE: SPACEFLIGHTNOW.COM

[neilep]

On the cutting edge: Carbon nanotube cutlery
Scanning electron micrograph of a prototype 'nanoknife' shows a single carbon nanotube stretched between two tungsten needles. Triangular probe is the tip of an atomic force cantilever used to determine...
Click here for more information.

Researchers at the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder (CU) have designed a carbon nanotube knife that, in theory, would work like a tight-wire cheese slicer. In a paper presented this month at the 2006 International Mechanical Engineering Congress and Exposition*, the research team announced a prototype nanoknife that could, in the future, become a tabletop tool of biology, allowing scientists to cut and study cells more precisely than they can today.

For years, biologists have wrestled with conventional diamond or glass knives, which cut frozen cell samples at a large angle, forcing the samples to bend and sometimes later crack. Because carbon nanotubes are extremely strong and slender in diameter, they make ideal materials for thinly cutting precise slivers of cells. In particular, scientists might use the nanoknife to make 3D images of cells and tissues for electron tomography, which requires samples less than 300 nanometers thick.

By manipulating carbon nanotubes inside scanning electron microscopes, 21st-century nanosmiths have begun crafting a suite of research tools, including nanotweezers, nanobearings and nano-oscillators. To design the nanoknife, the NIST and CU scientists welded a carbon nanotube between two electrochemically sharpened tungsten needles. In the resulting prototype, the nanotube stretches between two ends of a tungsten wire loop. The knife resembles a steel wire that cuts a block of cheese.

To begin demonstrating the feasibility of their knife design, the researchers assessed its mechanical strength in force tests, applying increasing pressure to the device. The team found that the welds were the weakest point of the nanoknife, and they are now experimenting with alternative welding techniques. The researchers plan to test the nanoknife on a block of wax later this year (cells typically are immobilized in wax for dissection and microscopy.)

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Caption: Scanning electron micrograph of a prototype
"nanoknife" shows a single carbon nanotube stretched between two tungsten
needles. Triangular probe is the tip of an atomic force cantilever used to
 determine the breaking point of the knife. (Color added for clarity.)

Credit: NIST/CU

SOURCE: EUREKA ALERT

[neilep]

Hubble Finds Evidence for Dark Energy in the Young Universe

Scientists using NASA's Hubble Space Telescope have discovered that dark energy is not a new constituent of space, but rather has been present for most of the universe's history. Dark energy is a mysterious repulsive force that causes the universe to expand at an increasing rate. Investigators used Hubble to find that dark energy was already boosting the expansion rate of the universe as long as nine billion years ago. This picture of dark energy is consistent with Albert Einstein's prediction of nearly a century ago that a repulsive form of gravity emanates from empty space. Data from Hubble provides supporting evidence to help astrophysicists to understand the nature of dark energy. This will allow them to begin ruling out some competing explanations that predict that the strength of dark energy changes over time.

Researchers also have found that the class of ancient exploding stars, or supernovae, used to measure the expansion of space today look remarkably similar to those that exploded nine billion years ago and are just now being seen by Hubble. This important finding gives additional credibility to the use of these supernovae for tracking the cosmic expansion over most of the universe's lifetime. Supernovae provide reliable measurements because their intrinsic brightness is well understood. They are therefore reliable distance markers, allowing astronomers to determine how far away they are from Earth. These snapshots, taken by Hubble reveal five supernovae and their host galaxies. The arrows in the top row of images point to the supernovae. The bottom row shows the host galaxies before or after the stars exploded. The supernovae exploded between 3.5 and 10 billion years ago.


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SOURCE: HUBBLESITE.ORG

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World's oldest ritual discovered
Worshipped the python 70,000 years ago



A startling archaeological discovery this summer changes our understanding of human history. While, up until now, scholars have largely held that man’s first rituals were carried out over 40, 000 years ago in Europe, it now appears that they were wrong about both the time and place.

Associate Professor Sheila Coulson, from the University of Oslo, can now show that modern humans, Homo sapiens, have performed advanced rituals in Africa for 70,000 years. She has, in other words, discovered mankind’s oldest known ritual.

The archaeologist made the surprising discovery while she was studying the origin of the Sanpeople. A group of the San live in the sparsely inhabited area of north-western Botswana known as Ngamiland.


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In the excavation they found more than 13,000 artifacts.



Coulson made the discovery while searching for artifacts from the Middle Stone Age in the only hills present for hundreds of kilometers in any direction. This group of small peaks within the Kalahari Desert is known as the Tsodilo Hills and is famous for having the largest concentration of rock paintings in the world.

The Tsodilo Hills are still a sacred place for the San, who call them the “Mountains of the Gods” and the “Rock that Whispers”.

The python is one of the San’s most important animals. According to their creation myth, mankind descended from the python and the ancient, arid streambeds around the hills are said to have been created by the python as it circled the hills in its ceaseless search for water.

Sheila Coulson’s find shows that people from the area had a specific ritual location associated with the python. The ritual was held in a little cave on the northern side of the Tsodilo Hills. The cave itself is so secluded and access to it is so difficult that it was not even discovered by archaeologists until the 1990s.

When Coulson entered the cave this summer with her three master’s students, it struck them that the mysterious rock resembled the head of a huge python. On the six meter long by two meter tall rock, they found three-to-four hundred indentations that could only have been man-made.

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PYTHON STONE


"You could see the mouth and eyes of the snake. It looked like a real python. The play of sunlight over the indentations gave them the appearance of snake skin. At night, the firelight gave one the feeling that the snake was actually moving".

They found no evidence that work had recently been done on the rock. In fact, much of the rock’s surface was extensively eroded.

When they saw the many indentations in the rock, the archaeologists wondered about more than when the work had been done. They also began thinking about what the cave had been used for and how long people had been going there. With these questions in mind, they decided to dig a test pit directly in front of the python stone.

At the bottom of the pit, they found many stones that had been used to make the indentations. Together with these tools, some of which were more than 70,000 years old, they found a piece of the wall that had fallen off during the work.

In the course of their excavation, they found more than 13,000 artifacts. All of the objects were spearheads and articles that could be connected with ritual use, as well as tools used in carving the stone. They found nothing else.

As if that were not enough, the stones that the spearheads were made from are not from the Tsodilo region but must have been brought from hundreds of kilometers away.

The spearheads are better crafted and more colourful than other spearheads from the same time and area. Surprisingly enough, it was only the red spearheads that had been burned.

"Stone age people took these colourful spearheads, brought them to the cave, and finished carving them there. Only the red spearheads were burned. It was a ritual destruction of artifacts. There was no sign of normal habitation. No ordinary tools were found at the site. Our find means that humans were more organised and had the capacity for abstract thinking at a much earlier point in history than we have previously assumed. All of the indications suggest that Tsodilo has been known to mankind for almost 100,000 years as a very special place in the pre-historic landscape.” says Sheila Coulson.

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The spearheads were particularly beautiful and were brought from hundreds of kilometers away.


Sheila Coulson also noticed a secret chamber behind the python stone. Some areas of the entrance to this small chamber were worn smooth, indicating that many people had passed through it over the years.

"The shaman, who is still a very important person in San culture, could have kept himself hidden in that secret chamber. He would have had a good view of the inside of the cave while remaining hidden himself. When he spoke from his hiding place, it could have seemed as if the voice came from the snake itself. The shaman would have been able to control everything. It was perfect.” The shaman could also have “disappeared” from the chamber by crawling out onto the hillside through a small shaft.

While large cave and wall paintings are numerous throughout the Tsodilo Hills, there are only two small paintings in this cave: an elephant and a giraffe. These images were rendered, surprisingly, exactly where water runs down the wall.

Sheila Coulson thinks that an explanation for this might come from San mythology.

In one San story, the python falls into a body of water and cannot get out by itself. The python is pulled from the water by a giraffe. The elephant, with its long trunk, is often used as a metaphor for the python.

"In the cave, we find only the San people’s three most important animals: the python, the elephant, and the giraffe. That is unusual. This would appear to be a very special place. They did not burn the spearheads by chance. They brought them from hundreds of kilometers away and intentionally burned them. So many pieces of the puzzle fit together here. It has to represent a ritual." concludes Sheila Coulson.



It was a major archaeological find five years ago that made it possible for Sheila Coulson to date the finds in this little cave in Botswana. Up until the turn of the century, archaeologists believed that human civilisation developed in Europe after our ancestors migrated from Africa. This theory was crushed by Archaeologist Christopher Henshilwood when he published his find of traces from a Middle Stone Age dwelling in the Blombos Cave in Southern Cape, South Africa.


SOURCE: EURELAALERT.ORG

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 Portrait of a Dramatic Stellar Crib


A new, stunning image of the cosmic spider, the Tarantula Nebula and its surroundings, finally pays tribute to this amazing, vast and intricately sculpted web of stars and gas. The newly released image, made with ESO's Wide Field Imager on the 2.2-m ESO/MPG Telescope at La Silla, covers 1 square degree on the sky and could therefore contain four times the full Moon.


ESO PR Photo 50a/06
The Tarantula Nebula (WFI/2.2m)

Known as the Tarantula Nebula for its spidery appearance, the 30 Doradus complex is a monstrous stellar factory. It is the largest emission nebula in the sky, and can be seen far down in the southern sky at a distance of about 170,000 light-years, in the southern constellation Dorado (The Swordfish or the Goldfish). It is part of one of the Milky Way's neighbouring galaxies, the Large Magellanic Cloud.

The Tarantula Nebula is thought to contain more than half a million times the mass of the Sun in gas and this vast, blazing labyrinth hosts some of the most massive stars known. The nebula owes its name to the arrangement of its brightest patches of nebulosity, that somewhat resemble the legs of a spider. They extend from a central 'body' where a cluster of hot stars (designated 'R136') illuminates and shapes the nebula. This name, of the biggest spiders on the Earth, is also very fitting in view of the gigantic proportions of the celestial nebula - it measures nearly 1,000 light-years across and extends over more than one third of a degree: almost, but not quite, the size of the full Moon. If it were in our own Galaxy, at the distance of another stellar nursery, the Orion Nebula (1,500 light-years away), it would cover one quarter of the sky and even be visible in daylight.

Because astronomers believe that most of the stars in the Universe were formed in large and hectic nurseries such as the 30 Doradus region, its study is fundamental. Early this year, astronomers took a new, wide look at the spider and its web of filaments, using the Wide Field Imager on the 2.2-m MPG/ESO telescope located at La Silla, Chile, while studying the dark clouds in the region. Dark clouds are enormous clouds of gas and dust, with a mass surpassing a million times that of the Sun. They are very cold, with temperatures about -260 degrees Celsius, and are difficult to study because of the heavy walls of dust behind which they hide. Their study is however essential, as it is in their freezing wombs that stars are born.




ESO PR Photo 50b/06
SN 1987A and the Honeycomb Nebula (WFI/2.2m)

Observing in four different bands, the astronomers made a mosaic of the half-degree field of view of the instrument to obtain an image covering one square degree. With each individual image containing 64 million pixels, the resultant mosaic thus contained 4 times as many, or 256 million pixels! The observations were made in very good image quality, the 'seeing' being typically below 1 arcsecond.

The image is based on data collected through four filters, including two narrow-band filters that trace hydrogen (red) and oxygen (green). The predominance of green in the Tarantula is a result of the younger, hotter stars in this region of the complex.

It would be easy to get lost in the meanderings of the filamentary structures or get stuck in the web of the giant arachnid, as is easily experienced with the zoom-in feature provided on the associated photo page, and it is therefore difficult to mention all the unique objects to be discovered. Deserving closer attention perhaps is the area at the right-hand border of the Tarantula. It contains the remains of a star that exploded and was seen with the unaided eye in February 1987, i.e. almost 20 years ago. Supernova SN 1987A, as it is known, is the brightest supernova since the one observed by the German astronomer Kepler in 1604. The supernova is known to be surrounded by a ring, which can be distinguished in the image.

A little to the left of SN 1987A, another distinctive feature is apparent: the Honeycomb Nebula. This characteristic bubble-like structure results apparently from the interaction of a supernova explosion with an existing giant shell, which was itself generated by the combined action of strong winds from young, massive stars and supernova explosions.


The image is based on observations carried out by João Alves (Calar Alto, Spain), Benoit Vandame and Yuri Bialetski (ESO) with the Wide Field Imager (WFI) at the 2.2-m telescope on La Silla. The colour composite was made by Bob Fosbury (ST-EcF).

Super Massive Piccys here http://www.eso.org/outreach/press-rel/pr-2006/phot-50-06.html

Excellent Zoomify here  http://www.eso.org/outreach/press-rel/pr-2006/images/phot-50a-06-w0.html

SOURCE:

>European Organisation for Astronomical Research in the Southern Hemisphere      
ESO
European Organisation
for Astronomical
Research in the
Southern Hemisphere
www.eso.rg

[neilep]

Psychedelic Saturn
CASSINI PHOTO RELEASE





Credit: NASA/JPL/Space Science Institute
Download larger image version here http://photojournal.jpl.nasa.gov/jpeg/PIA08858.jpg


This psychedelic view of Saturn and its rings is a composite made from images taken with the Cassini spacecraft wide-angle camera using spectral filters sensitive to wavelengths of infrared light centered at 728, 752 and 890 nanometers.

Cassini acquired the view in December at a distance of approximately 822,000 kilometers (511,000 miles) from Saturn. Image scale is 46 kilometers (28 miles) per pixel.



SOURCE: SPACEFLIGHTNOW.ORG

[neilep]

 
Shadows on ice
CASSINI PHOTO RELEASE

Canyons and mountain peaks snake along the terminator on the crater-covered, icy moon Dione. With the Sun at a low angle on their local horizon, the line of mountain ridges above center casts shadows toward the east.

Sunlit terrain seen here is on the anti-Saturn hemisphere of Dione (1,126 kilometers, or 700 miles across) -- the side that always faces away from Saturn. North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera in December at a distance of approximately 299,000 kilometers (186,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 81 degrees. Image scale is 2 kilometers (1 mile) per pixel.








Credit: NASA/JPL/Space Science Institute
Download larger image version here
http://photojournal.jpl.nasa.gov/jpeg/PIA08856.jpg[/color]




SOURCE: SPACEFLIGHTNOW.ORG

[neilep]

Pan's progress
CASSINI PHOTO RELEASE




Credit: NASA/JPL/Space Science Institute
Download larger image version here

http://photojournal.jpl.nasa.gov/jpeg/PIA08857.jpg

Pan is seen in this color view as it sweeps through the Encke Gap with its attendant ringlets. As the lemon-shaped little moon orbits Saturn, it always keeps its long axis pointed along a line toward the planet. From this vantage point, the dark side of the moon is visible.

This view looks toward Pan (26 kilometers, or 16 miles across) within the Encke Gap (325 kilometers, or 200 miles wide), on the unlit side of the rings, and from an inclination of about 33 degrees above the ringplane.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The image was taken with the Cassini spacecraft narrow-angle camera in December at a distance of approximately 779,000 kilometers (484,000 miles) from Pan and at a Sun-Pan-spacecraft, or phase, angle of 83 degrees. Image scale is 5 kilometers (3 miles) per pixel.


SOURCE: SPACEFLIGHTNOW.ORG