Astronomy Club of Ebene SSS(girls) - Latest AsTrOnOmY news!

Latest astronomy news from all around the world will be displayed on this page! So...
keep your fingers
crossed and let`s wait for the best
as well as the worst!

- Astronomers Find Highly Elliptical Disk Around early Star HD 15115

Astronomers using the Hubble Space Telescope and W. M. Keck Observatory have found a lopsided debris around a young star known as HD 15115. As seen from Earth, the edge-on disk resembles a needle sticking out from the star. Astronomers think the disk's odd imbalanced look is caused by dust following a highly elliptical orbit about the star. The lopsided disk may have been caused by the gravity of planets wide up debris in the disk or by the gravity of a nearby star. The observations were made by Paul Kalas, James Graham, and Michael P. Fitzgerald, all from the University of California at Berkeley. Their paper appeared in The Astrophysical Journal Letters. "The lopsided disk presents a host of new challenges for theorists," said Kalas. Debris disks are produced by dust from collisions among protoplanetary bodies, which are the building blocks of planets. These dusty disks can be precious by planets nearer to the star, much as Jupiter's gravity affects asteroids in the asteroid belt. This discovery is consistent with models for planetary upheavals in our own solar system, where Neptune may have originally formed between Saturn and Uranus. Neptune was eventually kicked out to its present location by a gravitational dance between Saturn and Jupiter before their orbits stabilized. "Therefore, we speculate that if such a planetary upheaval were occurring around HD 15115 at the present time, it could justify the highly asymmetric disk," Kalas said. This might happen through a powerful gravitational interaction between planets that kicks one or more planets into highly elliptical orbits, or even ejects them into interstellar space. When the planet's orbit becomes elliptical through a violent upheaval, the leftovers of the disk can be disturbed into an elliptical shape, according to Kalas. Kalas also is studying whether the gravity of a star known as HIP 12545, located about 10 light-years from HD 15115, may have created the disk's lopsided shape due to a close encounter in the past. Dusty disks are known to exist around at least 100 stars, but because of the difficulty in observing material within the glare of a star, less than a dozen have been studied closely. HD 15115 and HIP 12545 are among nearly 30 stars that belong to the Beta Pictoris Moving Group. Moving groups are expanded clusters of stars believed to have a common birthplace and age that are traveling loosely together through space. The dusty disk around HD 15115 was first inferred by observations at infrared wavelengths in 2000 and its existence confirmed in 2006 when the Hubble Space Telescope (HST) resolved the disk in reflected light for the first time. The disk was investigated further using Keck adaptive optics in 2006 and 2007. "The disk was seen in the HST data, but its appearance was so extraordinary we could not be certain that it was real. It took follow-up observations at Keck to confirm that it was a real disk," Kalas said.

Posted on Wed, 19 Dec 2007 01:02:00 +0300 in Astronomy club

Original article: Astronomers Find Highly Elliptical Disk Around early Star HD 15115 by at bautforum

- X-ray satellites find the biggest collisions in the Universe The orbiting X-ray telescopes XMM-Newton and Chandra have caught a pair of galaxy clusters merging into a giant cluster

X-ray satellites turn up the biggest collisions in the Universe The orbiting X-ray telescopes XMM-Newton and Chandra have caught a pair of galaxy clusters merging into a giant . The discovery adds to existing evidence that galaxy clusters can collide faster than previously thought. When individual galaxies collide and spiral into one another, they discard trails of hot gas that stretch across space, providing signposts to the mayhem. Recognising the signs of collisions between whole clusters of galaxies, however, is not as easy. Undaunted, Renato Dupke and colleagues from the University of Michigan, Ann Arbor, have used ESA XMM-Newton and NASAР В Р’В Chandra orbiting X-ray observatories, to disentangle the puzzling galaxy cluster, Abell 576. Previous X-ray observations had hinted that the gas was not moving uniformly across the cluster. Using the superior sensitivity and spectral resolution of XMM-Newton and Chandra high spatial resolution, Dupke took readings from two locations in the cluster and saw that there was a distinct difference in the velocity of the gas. One part of the cluster seemed to be moving away from us faster than the other. The enigma was that the moving gas itself was cold by astronomical standards. If this gas moved at such high speeds, it should have had a temperature of more than double the measured 50 million degrees Celsius. only reason was to take the Bullet Cluster and turn it in the line of sight, such that one galaxy cluster is directly behind the other says Dupke. The Bullet Cluster is a much-studied pair of galaxy clusters, which have collided head on. One has passed through the other, like a bullet travelling through an apple. In the Bullet Cluster, this is happening across our line of sight, so we can clearly see the two clusters. Dupke realised that Abell 576 is also a collision, but seen head on, so one cluster is now almost directly behind the other. The clouds of gas are the cores of each cluster, which have survived the initial collision but will eventually fall back together to become one. The data reveals that the clusters have collided at a speed of over 3300 km/s. This is interesting because there are some computer models of colliding galaxy clusters that suggest that such a high speed is impossible to reach. The bullet cluster Nevertheless, the Bullet Cluster is estimated to have a collision speed similar to the Abell 576 system. Р В Р’В Р В РІР‚В Р В Р’В Р Р†Р вЂљРЎв„ўР В Р Р‹Р РЋРІвЂћСћThere is now a growing body of evidence that these high collision velocities are possible, says Dupke. The job of explaining these high speeds now rests with the cosmologists. Major cluster-cluster collisions are expected to be rare, with estimates of their frequency ranging from less than one in a thousand clusters to one in a hundred. On collision, their internal gas is thrown out of equilibrium and if unrecognised, causes underestimation of its mass by between 5 and 20 percent. This is important because the masses of the various galaxy clusters are used to estimate the cosmological parameters that describe how the Universe expands. So, identifying colliding systems is extremely important to our understanding of the Universe. Dupke and colleagues are already investigating a number of other clusters that also appear to be interacting.

Posted on Mon, 17 Dec 2007 01:07:03 +0300 in Astronomy club

Original article: X-ray satellites find the biggest collisions in the Universe The orbiting X-ray telescopes XMM-Newton and Chandra have caught a pair of galaxy clusters merging into a giant cluster. by at bautforum

Astronomers invention Highly Elliptical Disk Around Young Star

Astronomers using the Hubble Space Telescope and W. M. Keck Observatory have found a lopsided debris around a young star known as HD 15115. As seen from Earth, the edge-on disk resembles a needle sticking out from the star. Astronomers think the disk's odd imbalanced look is caused by dust following a highly elliptical orbit about the star. The lopsided disk may have been caused by the gravity of planets far-reaching up debris in the disk or by the gravity of a nearby star. The observations were made by Paul Kalas, James Graham, and Michael P. Fitzgerald, all from the University of California at Berkeley. Their paper appeared in The Astrophysical Journal Letters. "The lopsided disk presents a host of new challenges for theorists," said Kalas. Debris disks are produced by dust from collisions among protoplanetary bodies, which are the building blocks of planets. These dusty disks can be artificial by planets nearer to the star, much as Jupiter's gravity affects asteroids in the asteroid belt. This discovery is consistent with models for planetary upheavals in our own solar system, where Neptune may have originally formed between Saturn and Uranus. Neptune was eventually kicked out to its present location by a gravitational dance between Saturn and Jupiter before their orbits stabilized. "Therefore, we speculate that if such a planetary upheaval were occurring around HD 15115 at the present time, it could explain the highly asymmetric disk," Kalas said. This might happen through a powerful gravitational interaction between planets that kicks one or more planets into highly elliptical orbits, or even ejects them into interstellar space. When the planet's orbit becomes elliptical through a violent upheaval, the recreation of the disk can be disturbed into an elliptical shape, according to Kalas. Kalas also is studying whether the gravity of a star known as HIP 12545, located about 10 light-years from HD 15115, may have created the disk's lopsided shape due to a close encounter in the past. Dusty disks are known to exist around at least 100 stars, but because of the difficulty in observing material within the glare of a star, less than a dozen have been studied closely. HD 15115 and HIP 12545 are among nearly 30 stars that belong to the Beta Pictoris Moving Group. Moving groups are expanded clusters of stars believed to have a common birthplace and age that are traveling loosely together through space. The dusty disk around HD 15115 was first inferred by observations at infrared wavelengths in 2000 and its existence confirmed in 2006 when the Hubble Space Telescope (HST) resolved the disk in reflected light for the first time. The disk was investigated further using Keck adaptive optics in 2006 and 2007. "The disk was seen in the HST data, but its appearance was so extraordinary we could not be certain that it was real. It took follow-up observations at Keck to confirm that it was a real disk," Kalas said.

Posted on Thu, 13 Dec 2007 01:47:39 +0300 in Astronomy club

Original article: Astronomers invention Highly Elliptical Disk Around Young Star by at bautforum.

The search for life on Mars

HiRISE discovers a possibly once-habitable ancient lake on the Red Planet.

Provided by the University of Arizona, Tuscon

Scientists studying images from the University of Arizona-led High Resolution Imaging Experiment camera on NASA's Mars Reconnaissance Orbiter have discovered never-before-seen impact megabreccia and a possibly once-habitable ancient lake on Mars at a place called Holden crater.

The megabreccia is topped by layers of fine sediments that formed in what apparently was a long-lived, calm lake that filled Holden crater on early Mars, HiRISE scientists say.

"Holden crater has some of the best-exposed lake deposits and ancient megabreccia known on Mars," says HiRISE's principal investigator, professor Alfred McEwen of the UA's Lunar and Planetary Laboratory. "Both contain minerals that formed in the presence of water and mark potentially habitable environments. This would be an excellent place to send a rover or sample-return mission to make major advances in understanding if Mars supported life."

Holden crater is an impact crater that formed within an older, multi-ringed impact basin called Holden basin. Before an impact created Holden crater, large channels crossed and deposited sediments in Holden basin.

Blocks as big as 50 meters across were blasted from Holden basin when Holden crater formed, then fell chaotically back to the surface and eventually formed megabreccia, a conglomeration of large, broken boulders mixed with smaller particles. HiRISE images show megabreccia outcrops in Holden crater walls. This megabreccia may be some of the oldest deposits exposed on the surface of Mars.

At least 5 percent, by weight, of the fine sediments in the layer on top of the megabreccia consists of clay, according to another instrument on the Mars Reconnaissance Orbiter, the Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM.

"The origin of the clays is uncertain, but clays in the probable lake sediments implies quiescent conditions that may preserve signatures of a past habitable environment," HiRISE co-investigator John Grant of the Smithsonian National Air and Space Museum says. "If we were looking on Earth for an environment that preserves signatures related to habitability, this is one of the kinds of environments we would look at."

And even the clay-containing layers aren't all that's icing the cake. Topping the clay layers that formed in the placid Holden crater lake are layers of great boulder-filled debris unleashed later, when water breached Holden crater rim, creating a torrential flood that eroded the older lake sediments.

The clay-rich layers would have remained buried from view, except for that great piece of luck, the fact that Holden crater rim could no longer withstand the force of an estimated 4,000 cubic kilometers of water dammed behind it. The body of water would have been larger than Lake Huron.

"The volume of water that poured through during this flood must have been spectacular," Grant says. "It ripped up finely bedded materials, including blocks 70 meters or 80 meters across, blocks nearly the size of football fields."

The first, prolonged watery episode at Holden crater that settled out the fine-grain sediments probably lasted at least thousands of years. By contrast, the second lake, formed when the crater rim was breached, may have lasted only hundreds of years, not long at all, Grant says.

The megabreccia excavated when Holden crater formed is the first found on Mars, Grant says. "When large craters form, they produce very large blocks of material. We see them on Earth. Popigai Crater in Russia is one example. But we'd never seen them on Mars, and we knew they ought to be there. Now we've seen them with HiRISE."

The observations suggest that the clays originally could have formed before the impact created Holden crater in the older Holden basin. Many of the blocks in the megabreccia appear to erode more easily than the surrounding crater wall material. These blocks could be chunks of Holden basin sediments that predate the impact crater, Grant said. "These blocks could be derived from the earlier Holden basin that were excavated on impact, then later re-eroded, with the sediments settling to the bottom of the long-lived lake. It's intriguing to think the clays we see in Holden crater now might actually have been recycled."

Holden crater is one of six remaining landing site candidates for NASA's Mars Science Laboratory, a mission scheduled for launch next year.

So far, most evidence for sustained wet conditions on Mars is limited to the planet's earliest history, the HiRISE scientists say. While water certainly flowed over the planet later in its history, it may have flowed only in short-lived, or catastrophic events.

Study: Life's Raw Material Came from Space

We may all be aliens, it seems.

Some of the building blocks of life on Earth came from space, according to a new study of molecules in meteorite fragments.

The study confirmed that some of the raw material for DNA and RNA found in a meteorite did not contaminate the rock after it landed on Earth, but actually originated in space.

The materials in question are the molecules uracil and xanthine, which are precursors to the compounds that make up DNA and RNA, and are known as nucleobases.

"We believe early life may have adopted nucleobases from meteoritic fragments for use in genetic coding which enabled them to pass on their successful features to subsequent generations," said the study's lead author, Zita Martins, a researcher in the Department of Earth Science and Engineering at Imperial College London.

Martins and her colleagues detailed their findings in the June 15 issue of the journal Earth and Planetary Science Letters.

The team discovered the molecules in rock fragments of the Murchison meteorite, which crashed in Australia in 1969. The scientists analyzed the genetic building blocks and found that they contain a heavy form of carbon which could only have been formed in space. Materials formed on Earth are made of a lighter type of carbon.

The two molecules in this study are only a few of the organic molecules that have been detected in the famous Murchison meteorite, said David Deamer, a chemist at the University of California, Santa Cruz.

"There are about 70 different amino acids in the Murchison meteorite," Deamer told SPACE.com. "About six or so are the same kinds of amino acids associated with life on Earth."

Uracil is one of the four base molecules of RNA, so is vital for life.

Just because the molecules found on this meteorite and others came from space, doesn't mean the same compounds weren't also independently synthesized on Earth, Deamer pointed out. Scientists are unsure how many of the building blocks of life on Earth originated on this planet, and how many came from beyond.

"We don't know the answer yet," he said. "Most people would say that both contributed to the organic compounds available on Earth, but we don't know with certainty how much of one compared to the other."

Many space rocks similar to the Murchison meteorite rained down on Earth between 3.8 and 4.5 billion years ago, when primitive life was forming. The heavy bombardment would have dropped large amounts of meteorite material to the surface on planets such as Earth and Mars.

Martins and her colleagues say their discovery may help shed light on how life first evolved in our solar system.

"Because meteorites represent leftover materials from the formation of the solar system, the key components for life - including nucleobases - could be widespread in the cosmos," said co-author Mark Sephton, a professor of Earth science and engineering at Imperial College London. "As more and more of life's raw materials are discovered in objects from space, the possibility of life springing forth wherever the right chemistry is present becomes more likely."