Hubble Spies Shells Of Sparkling Stars Around Quasar

Source:

http://www.sciencedaily.com/releases/2007/10/071025143300.htm

ScienceDaily (Oct. 30, 2007) — New images taken with NASA's Hubble Space Telescope -- part of a research project led by UC Riverside's Gabriela Canalizo -- have revealed the wild side of an elliptical galaxy, nearly two billion light-years away, that previously had been considered mild-mannered.

The Hubble photos show shells of stars around a bright quasar, known as MC2 1635+119, which dominates the center of the galaxy. The presence of the shells is an indication of a titanic clash with another galaxy in the relatively recent past.
The collision, which is funneling gas into the galaxy's center, is feeding a supermassive black hole. The accretion onto the black hole is the quasar's energy-source.
"This observation supports the idea that some quasars are born from interactions between galaxies," said Canalizo, an assistant professor of astrophysics in the Department of Physics and Astronomy, and a member of the Institute of Geophysics and Planetary Physics. "It also provides more evidence that mergers are crucial for triggering quasars. Most quasars were active in the early universe, which was smaller, so galaxies collided more frequently.
"Astronomers have long speculated that quasars are fueled by interactions that bring an inflow of gas to the black holes in the centers of galaxies. Since this quasar is relatively nearby, it is a great laboratory for studying how more distant quasars are turned on."
Canalizo explained that the period of time when the central black hole of a galaxy is actively accreting material as a quasar is believed to be an essential phase in the evolution of most galaxies.
"For many decades now, there has been much debate regarding whether galaxy mergers or collisions are responsible for fueling their central black holes and turning them into quasars," she said.
Discovered nearly 50 years ago, quasars are among the brightest objects in the universe. They reside in the centers of galaxies and are powered by supermassive black holes.
Previous studies of the MC2 1635+119 galaxy with ground-based telescopes showed a normal-looking elliptical containing an older population of stars. It took the razor-sharp vision of Hubble's Advanced Camera for Surveys and the spectroscopic acuity of the W.M. Keck Observatory in Hawaii to uncover the faint, thin shells.
The new Hubble observations reveal at least five inner shells and additional debris traveling away from the galaxy's center. The shells, which sparkle with stars, resemble ripples forming in a pond when a stone is tossed in. They formed when a galaxy was shredded by tidal forces during the collision. Some of the galaxy's stars were swept up in the elliptical galaxy's gravitational field, creating the outward-moving shells. The farthest shell is about 40,000 light-years away from the center.
"This is the most spectacular shell galaxy seen at this distance," said team member Francois Schweizer of the Carnegie Observatories in Pasadena, California.
Computer simulations estimate that the encounter happened 1.7 billion years ago. The merger itself occurred over a few hundred million years and stoked a flurry of star birth. Spectroscopic data from Keck reveal that many of the stars in the galaxy are 1.4 billion years old, consistent with the age of the merger.
The shell stars are mixing with the stars in the galaxy as they travel outward. Eventually, the shells will dissipate and the stars will be scattered throughout the galaxy.
"This could be a transitory phase, common to most ellipticals, that lasts only 100 million to a billion years," Canalizo said. "So, seeing these shells tells us that the encounter occurred in the relatively recent past. Hubble caught the shells at the right time."
Canalizo and her team have yet to determine the type of merger responsible for the shells and the quasar activity. Their evidence, however, points to two possible collision scenarios.
"The shells' formation and the current quasar activity may have been triggered by an interaction between two large galaxies or between a large galaxy and a smaller galaxy," explained team member Nicola Bennert of UCR, who did all of the data processing and quantitative measurements, as well as a large fraction of the analysis. "We need high-resolution spectroscopic observations of the quasar host galaxy to determine the type of merger."
The quasar is part of an Advanced Camera for Surveys study of five galaxies, all roughly 2 billion light-years away, that are known to harbor quasars. According to Canalizo, the other four galaxies analyzed also display evidence of encounters. Her team also is using Hubble's Wide Field Planetary Camera 2 to sample 14 more galaxies with quasars.
"We want to know whether most quasars at current epochs begin their lives as mergers, or whether they simply occur in old ellipticals to which nothing very interesting has happened recently," Canalizo said.
Canalizo, Bennert and Schweizer were joined in the study by UCR's Bruno Jungwiert, who was in charge of the numerical simulations; Alan Stockton of the University of Hawaii, Honolulu; Mark Lacy of the California Institute of Technology, Pasadena; and Chien Peng of the Herzberg Institute of Astrophysics in Victoria, British Columbia.
Study results will appear in the Nov. 10 issue of The Astrophysical Journal.
Adapted from materials provided by University of California - Riverside.

Fausto Intilla

www.oloscience.com

Missing Black Hole Report: Hundreds Found!

Source:

http://www.sciencedaily.com/releases/2007/10/071025150029.htm

ScienceDaily (Oct. 25, 2007) — Astronomers have unmasked hundreds of black holes hiding deep inside dusty galaxies billions of light-years away.

The massive, growing black holes, discovered by NASA's Spitzer and Chandra space telescopes, represent a large fraction of a long-sought missing population. Their discovery implies there were hundreds of millions of additional black holes growing in our young universe, more than doubling the total amount known at that distance.
"Active, supermassive black holes were everywhere in the early universe," said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. "We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself." Dickinson is a co-author of two new papers appearing in the Nov. 10 issue of the Astrophysical Journal. Emanuele Daddi of the Commissariat a l'Energie Atomique in France led the research.
The findings are also the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths building monstrous black holes at their cores.
For decades, a large population of active black holes has been considered missing. These highly energetic structures belong to a class of black holes called quasars. A quasar consists of a doughnut-shaped cloud of gas and dust that surrounds and feeds a budding supermassive black hole. As the gas and dust are devoured by the black hole, they heat up and shoot out X-rays. Those X-rays can be detected as a general glow in space, but often the quasars themselves can't be seen directly because dust and gas blocks them from our view.
"We knew from other studies from about 30 years ago that there must be more quasars in the universe, but we didn't know where to find them until now," said Daddi.
Daddi and his team initially set out to study 1,000 dusty, massive galaxies that are busy making stars and were thought to lack quasars. The galaxies are about the same mass as our own spiral Milky Way galaxy, but irregular in shape. At 9 to 11 billion light-years away, they existed at a time when the universe was in its adolescence, between 2.5 and 4.5 billion years old.
When the astronomers peered more closely at the galaxies with Spitzer's infrared eyes, they noticed that about 200 of the galaxies gave off an unusual amount of infrared light. X-ray data from Chandra, and a technique called "stacking," revealed the galaxies were, in fact, hiding plump quasars inside. The scientists now think that the quasars heat the dust in their surrounding doughnut clouds, releasing the excess infrared light.
"We found most of the population of hidden quasars in the early universe," said Daddi. Previously, only the rarest and most energetic of these hidden black holes had been seen at this early epoch.
The newfound quasars are helping answer fundamental questions about how massive galaxies evolve. For instance, astronomers have learned that most massive galaxies steadily build up their stars and black holes simultaneously until they get too big and their black holes suppress star formation.
The observations also suggest that collisions between galaxies might not play as large a role in galaxy evolution as previously believed. "Theorists thought that mergers between galaxies were required to initiate this quasar activity, but we now see that quasars can be active in unharassed galaxies," said co-author David Alexander of Durham University, United Kingdom.
"It's as if we were blindfolded studying the elephant before, and we weren't sure what kind of animal we had," added co-author David Elbaz of the Commissariat a l'Energie Atomique. "Now, we can see the elephant for the first time."
The new observations were made as part of the Great Observatories Origins Deep Survey, the most sensitive survey to date of the distant universe at multiple wavelengths.
Consistent results were recently obtained by Fabrizio Fiore of the Osservatorio Astronomico di Roma, Italy, and his team. Their results will appear in the Jan. 1, 2008, issue of Astrophysical Journal.
Adapted from materials provided by NASA/Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Boosting The Accuracy Of Rosetta's Earth Approach

Source:

http://www.sciencedaily.com/releases/2007/10/071019102623.htm

ScienceDaily (Oct. 22, 2007) — On October 18 at 18:06 CEST, the thrusters of ESA’s comet chaser, Rosetta, were fired in a planned, 42-second trajectory correction manoeuvre designed to 'fine tune' the spacecraft's approach to Earth. Rosetta is now approaching Earth for its second planetary swing-by of 2007.

The process took place automatically since the on-board antenna was pointed away from the ground station during the slew and could not receive radio commands; signals from Rosetta were reacquired at ESA's New Norcia deep-space ground station at 20:39 CEST (18:39 UTC).
The burn took place during one of five preplanned slots which are available to mission controllers based on determination of the spacecraft's actual trajectory by flight dynamics and other experts working on the Mission Control Team at ESA's European Space Operations Centre (ESOC), Darmstadt, Germany.
Optimising orbits and saving fuel
"We have a target trajectory for Earth swing-by and regular orbit determinations allow us to decide when to do a correction manoeuvre. Brief burns now allow us to optimise the orbit and make the swing-by more accurate, saving us a lot of precious fuel later on," said Andrea Accomazzo, Rosetta Spacecraft Operations Manager at ESOC. He confirmed that yesterday's manoeuvre results were as expected.
A second trajectory correction slot, on 1 November, may also be used depending on results of an orbit determination scheduled for 30 October.
The third Earth swing-by - and last of the four - will take place in November 2009.
Significant science: On to Steins
After November's Earth encounter, Rosetta will continue on its journey and next pass Asteroid Steins, providing an excellent opportunity for science investigations. Steins is relatively small, with a diameter of a few kilometres, and Rosetta is predicted to pass by on 5 September 2008 at a distance of just over 1700 km. This encounter will take place at a relatively low speed of about 9 km/sec during Rosetta's first excursion into the asteroid belt.
ESA's Comet Chaser
Rosetta will be ESA's first spacecraft to undertake long-term exploration of a comet at close quarters. The mission consists of a large orbiter, designed to operate for a decade at large distances from the Sun, and a small lander, Philae.
Each of these carries a large suite of scientific experiments designed to complete the most detailed study of a comet ever attempted.
After entering orbit around Comet 67P/Churyumov-Gerasimenko in 2014, the spacecraft will release the lander onto the icy nucleus.
It will then spend the next two years orbiting the comet as it heads toward the Sun. On the way to Comet Churyumov-Gerasimenko, Rosetta has received gravity assists from Earth and Mars, and will fly past two main-belt asteroids – Steins (September 2008) and Lutetia (July 2010).

Adapted from materials provided by European Space Agency.

Fausto Intilla

www.oloscience.com

Heaviest Stellar Black Hole Discovered In Nearby Galaxy

Source:

http://www.sciencedaily.com/releases/2007/10/071017145225.htm

Science Daily — Astronomers have located an exceptionally massive black hole in orbit around a huge companion star. This result has intriguing implications for the evolution and ultimate fate of massive stars.

The black hole is part of a binary system in M33, a nearby galaxy about 3 million light years from Earth. By combining data from NASA's Chandra X-ray Observatory and the Gemini telescope on Mauna Kea, Hawaii, the mass of the black hole, known as M33 X-7, was determined to be 15.7 times that of the Sun. This makes M33 X-7 the most massive stellar black hole known. A stellar black hole is formed from the collapse of the core of a massive star at the end of its life.
"This discovery raises all sorts of questions about how such a big black hole could have been formed," said Jerome Orosz of San Diego State University, lead author of the paper appearing in the October 18th issue of the journal Nature.
M33 X-7 orbits a companion star that eclipses the black hole every three and a half days. The companion star also has an unusually large mass, 70 times that of the Sun. This makes it the most massive companion star in a binary system containing a black hole.
"This is a huge star that is partnered with a huge black hole," said coauthor Jeffrey McClintock of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "Eventually, the companion will also go supernova and then we'll have a pair of black holes."
The properties of the M33 X-7 binary system - a massive black hole in a close orbit around a massive companion star - are difficult to explain using conventional models for the evolution of massive stars. The parent star for the black hole must have had a mass greater than the existing companion in order to have formed a black hole before the companion star.
Such a massive star would have had a radius larger than the present separation between the stars, so the stars must have been brought closer while sharing a common outer atmosphere. This process typically results in a large amount of mass being lost from the system, so much that the parent star should not have been able to form a 15.7 solar-mass black hole.
The black hole's progenitor must have shed gas at a rate about 10 times less than predicted by models before it exploded. If even more massive stars also lose very little material, it could explain the incredibly luminous supernova seen recently as SN 2006gy. The progenitor for SN 2006gy is thought to have been about 150 times the mass of the Sun when it exploded.
"Massive stars can be much less extravagant than people think by hanging onto a lot more of their mass toward the end of their lives," said Orosz. "This can have a big effect on the black holes that these stellar time-bombs make."
Coauthor Wolfgang Pietsch was also the lead author of an article in the Astrophysical Journal that used Chandra observations to report that M33 X-7 is the first black hole in a binary system observed to undergo eclipses. The eclipsing nature enables unusually accurate estimates for the mass of the black hole and its companion.
"Because it's eclipsing and because it has such extreme properties, this black hole is an incredible test-bed for studying astrophysics," said Pietsch.
The length of the eclipse seen by Chandra gives information about the size of the companion. The scale of the companion's motion, as inferred from the Gemini observations, gives information about the mass of the black hole and its companion. Other observed properties of the binary were used to constrain the mass estimates.
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Gemini is an international partnership managed by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation.
Note: This story has been adapted from material provided by Chandra X-ray Center.

Fausto Intilla

www.oloscience.com

Mars Express: Hummocky And Shallow Maunder Crater

Source:

http://www.sciencedaily.com/releases/2007/10/071016131458.htm

Science Daily — The High Resolution Stereo Camera (HRSC) on ESA’s Mars Express orbiter has obtained pictures of the Noachis Terra region on Mars, in particular, the striking Maunder crater.

Maunder crater lies at 50° South and 2° East, approximately in the center of Noachis Terra.
The impact crater, named after the british astronomer Edward W. Maunder (1851-1928), is located halfway between Argyre Planitia and Hellas Planitia on the southern Highlands of Mars.
With a diameter of 90 kilometres and a depth of barely 900 metres, the crater is not one of the largest impact craters on Mars at present, but it used to be much deeper. It has since been filled partially with large amounts of material.
The west of the crater experienced a major slope failure, during which a large landslide transported loose material eastward, to the inner parts of the crater. The edges of the crater rim that collapsed exhibit gullies which might be associated with the mass transport of the material.
The transition zone from the western rim of the crater to the rather smooth crater floor on the eastern edge shows hummocky terrain. Such terrain exhibits small, irregularly-shaped hills and valleys. The hummocky terrain in the Maunder crater was formed by deposition of landslide debris.
In the east, the crater floor is bounded by a trough, approximately 700 metres deep. The trough may be associated with a landslide on the western edge of the crater. Some gullies can be seen on the upper edge of the trough which is possible evidence for water seepage.
The small, 500 to 2500-metre long, dark features on the crater floor are eye-catching. These features are called Barchan dunes, one of the most abundant dune forms in arid environments. Dunes of this kind are also found on Earth, for example in the West-African Namib desert.
The colour scenes have been derived from the three HRSC-colour channels and the nadir channels. The perspective views have been calculated from the digital terrain model derived from the HRSC stereo channels. The anaglyph image was calculated from the nadir channels and two stereo channels, stereoscopic glasses are required for viewing. The 3-D (anaglyph) picture has been put together from several individual 3-D images of different scenes, enhancing the view over larger areas.
Note: This story has been adapted from material provided by European Space Agency.

Fausto Intilla

www.oloscience.com

Most Powerful Supernova Ever Discovered: 100 Billion Times Brighter Than The Sun

Source:

http://www.sciencedaily.com/releases/2007/10/071016085212.htm

Science Daily — Astronomer Robert Quimby has done it again. Found the most luminous supernova ever, that is.

Quimby discovered the current record holder, supernova 2006gy, last year as part of his Texas Supernova Search project. Now he announces that a supernova he discovered earlier in the project is actually twice as luminous. Using follow-up studies to pinpoint its distance, supernova 2005ap peaked at more than 100 billion times the brightness of the Sun.
This supernova is a Type II, Quimby said, because it contains hydrogen. Most Type II supernovae are thought to result when the cores of massive stars, those seven to eight times or more heavy than the Sun, collapse under their own weight and trigger an explosion. This particular Type II is 300 times brighter than average, Quimby said, and lies in a dwarf galaxy in the constellation Coma Berenices, well behind the famous Coma cluster of galaxies.
“It’s clearly not the same as 2006gy,” Quimby’s colleague and supernova expert J. Craig Wheeler of The University of Texas at Austin said. “It’s a puzzle.”
Quimby completed his Ph.D. under Wheeler’s supervision at Texas in May, and has just begun a post-doctoral appointment at Caltech. His Texas Supernova Search uses the 18-inch ROTSE-IIIb robotic telescope on McDonald Observatory’s Mount Fowlkes, a tiny neighbor to the giant 10-meter-class Hobby-Eberly Telescope (HET).
Quimby studied 2005ap with HET just a few days after its discovery. The results were intriguing, Quimby said. The supernova’s spectrum hinted at the presence of a highly shifted absorption line of oxygen III (an oxygen atom that has lost two of its electrons). Quimby knew that if the feature was oxygen III, then 2005ap was “possibly very far away and thus very luminous.”
Follow-up observations with the Keck Telescope in Hawaii by Quimby’s colleague Greg Aldering of Lawrence Berkeley National Lab not only confirmed Quimby’s HET detection of oxygen III, but added another, equally shifted element to the spectrum: magnesium.
Together, the studies confirmed 2005ap’s distance of 4.7 billion light-years. (In astronomical terms, this equates to a redshift of z = 0.2832.)
It was this distance measurement, combined with measurements of the supernova’s apparent brightness that allowed the calculation of its intrinsic brightness, or “luminosity,” and uncovered 2005ap as the most powerful supernova yet.
“Before 2006gy, I thought this should not be plausible,” Quimby said. “There I was finding my first supernovae — I was just happy to get anything. It turned out to be the most luminous supernova ever found.”
How is that Quimby has found the brightest supernova yet, twice in a row? “I’ve worked too damn hard for this to be luck,” he said.
Quimby explained, “I’m searching a huge volume of space, comparable to all previous nearby supernova surveys combined.” Also, Quimby will find supernovae that other studies ignore: he doesn’t filter out non-Type Ia supernovae, which is what many studies do that are searching for supernovae for cosmology studies, and he does search dwarf galaxies as well as galaxies with active black holes at their centers, which other studies avoid. Others also avoid supernovae near the cores of galaxies.
In fact, 2006gy was found in the core of a galaxy, and that galaxy has a weakly active central black hole, Wheeler said.
“There’s no question that [his results] have gotten everybody’s attention,” Wheeler said. The University of Michigan-run ROTSE collaboration, whose main mission is the search for gamma-ray bursts, has decided to expand the supernova search to its entire network. Its robotic telescopes in Australia, Turkey, and Namibia will soon join the unit at McDonald Observatory in this search. The Sloan Digital Sky Survey Supernova Search, for which the HET provides confirming spectra, is also reconsidering its search filters in response to these discoveries, Wheeler said.
The result has been accepted for publication in the October 20 edition of The Astrophysical Journal Letters.
The Hobby-Eberly Telescope is a joint project of The University of Texas at Austin, The Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München and Georg-August-Universität Göttingen.
Note: This story has been adapted from material provided by McDonald Observatory.

Fausto Intilla

www.oloscience.com

Long-lost, Dangerous Asteroid Is Found Again

Source:

http://www.sciencedaily.com/releases/2007/10/071011213216.htm

Science Daily — Echoing the re-discovery of America by the Spanish long after an earlier Viking reconnaissance, astronomers have learned that a recently observed asteroid - one that could potentially hit the Earth - was actually first observed nearly a half-century ago. Researchers at the Minor Planet Center of the Smithsonian Astrophysical Observatory in Cambridge, MA have confirmed work by SETI Institute astronomer Peter Jenniskens that the recently discovered asteroid 2007 RR9 is in fact the long-lost object 6344 P-L.

6344 P-L was last seen in 1960, and ever since has had the peculiar distinction of being the only Potentially Hazardous Asteroid without a formal designation. "The object was long recognized to be dangerous, but we didn't know where it was," says Jenniskens. "Now it is no longer just out there."
A designation as Potentially Hazardous means that 2007 RR9 is one of 886 (not 887) known asteroids bigger than 150 m (500 ft) in diameter that come to within 0.05 astronomical units of Earth's orbit (roughly 7,480,000 km or 4,650,000 miles). The size is estimated on the basis of the object's observed brightness and an assumed reflectance of 13 percent.
Jenniskens believes that this object may not, in fact, be an asteroid. "This is a now-dormant comet nucleus, a fragment of a bigger object that, after breaking up in the not-so-distant past, may have caused the gamma Piscid shower of slow meteors (IAU #236) that is active in mid-October and early November," he says. 2007 RR9 moves in a 4.70-year orbit, nearly all the way out to the distance of Jupiter. Because of this elongated orbit, it has a Tisserand parameter of T = 2.94, which defines it dynamically as a Jupiter Family Comet (T = 2.0 - 3.0), not an asteroid (T > 3.0).
So far, this object has not yet been seen to be even weakly active, but the now dormant comet is still moving closer to the Sun. It is sliding rapidly toward visibility in the southern hemisphere, and is expected to brighten to magnitude +18.5 in mid-October. According to Gareth V. Williams of the Minor Planet Center, it will pass Earth around November 6 at 0.07 AU, when the minor planet is at high latitudes in southern skies.
The original designation of P-L stands for "Palomar-Leiden," the juxtaposition of two observatory names that reflect what was a very fruitful collaboration by the trio of pioneer asteroid searchers Tom Gehrels of the University of Arizona, and Ingrid van Houten-Groeneveld and her husband Cornelis Johannes van Houten. Gehrels made a sky survey using the 48-inch Schmidt Telescope at the famed Palomar Observatory, long before modern asteroid reconnaisances, and shipped the photographic plates to the van Houtens at Leiden Observatory in the Netherlands. There, Ingrid discovered 6344 P-L on four plates taken on September 24-28, 1960. The trio are jointly credited with several thousand asteroid discoveries, but only 6344 P-L is a potential danger to Earth.
Peter Jenniskens is a meteor astronomer with the SETI Institute and author of "Meteor Showers and their Parent Comets" published by Cambridge University Press (2006). He is also credited with the identification of the parent body of the Quadrantid meteor shower. As it happens, he graduated from Leiden Observatory in 1992, before joining the SETI Institute.
Note: This story has been adapted from material provided by SETI Institute.

Fausto Intilla

www.oloscience.com

Search For Extraterrestrial Intelligence: Allen Telescope Array Begins Scientific Observations

Source:

http://www.sciencedaily.com/releases/2007/10/071011213855.htm

Science Daily — The University of California, Berkeley and the SETI Institute have announced that the first 42 radio dishes of the Allen Telescope Array (ATA) have been activated and collecting scientific data from the far reaches of the universe. This is the first phase of a planned 350 radio dishes that will advance the capabilities of radio astronomy research. Paul G. Allen, Microsoft co-founder and philanthropist whose foundation donated seed money that started the project in 2001, joined representatives of UC Berkeley and the SETI Institute to launch the array.

“This is a great day for the science of radio astronomy and the study of the cosmos,” said Leo Blitz, UC Berkeley professor of astronomy and director of the university’s Radio Astronomy Laboratory, which is building the ATA with the SETI Institute. “Thanks to a unique intersection between the best in science, advanced, innovative technology and bold philanthropy, many secrets of the universe are a little closer to being revealed.”
"This project represents a potential breakthrough in building large arrays of radio telescopes that are extremely cost effective,” said Paul G. Allen, primary funder of the ATA. “As now deployed and with plenty of room for growth in the future, the telescope can fulfill a multitude of uses, including broad radio sky surveys and the search for evidence of extraterrestrial technology. I’m pleased to be able to contribute to such an important advancement and help build on the work this new telescope will do in the future. My hat is off to the team that worked so hard these last seven years to accomplish this significant milestone.”
Every object in space emits radio waves that can be collected and studied. From observation of these signals, radio astronomers can create a picture of astronomical bodies and events at great distances, revealing detail not discernable by telescopes operating at other wavelengths. The ATA will acquire data in a new way, imaging a large piece of the sky at once. What sets the ATA apart from earlier radio telescopes is its ability to collect and, analyze more information about celestial objects, and do this simultaneously for several projects. In addition, observational surveys can be made with greater speed than any previous or existing radio device.
“For SETI, the ATA’s technical capabilities exponentially increase our ability to search for intelligent signals, and may lead to the discovery of thinking beings elsewhere in the universe,” said astronomer Seth Shostak of the SETI Institute in Mountain View, Calif. “It is the first major telescope in the world built specifically for undertaking a search for extraterrestrial intelligence.”
The ATA opens the doors to a new era of scientific progress. The telescope’s potential discoveries include a better understanding of exploding stars (supernovas), black holes, and new, exotic astronomical objects that are predicted but not yet observed. It will also provide expanded search capabilities to determine if intelligent civilizations have evolved around other stars. The ATA is the first panchromatic, wide-angle, snapshot, radio camera ever built. It is the most effective tool to create radio images of a vast area of the sky ever placed in the hands of researchers.
Located in an arid valley near the town of Hat Creek, just north of Lassen Volcanic National Park in northern California, the new array is already collecting important data. The first test images, released today from data gathered by the 42 ATA telescopes, include a radio map of the nearby Andromeda Galaxy (M31) and the Triangulum Galaxy (M33).
Beyond its speed and ability to both garner and analyze data, the ATA is also the first centimeter wavelength radio telescope with the ability to multi-task. While making innovative observations for radio astronomy, it can simultaneously interrogate solar-type stars for artificially produced signals that would reveal the presence of extraterrestrial intelligence.
This new capability increases many-fold the time astronomers can devote to large-scale surveys of the stars, as well as expanding the radio frequency band over which they can search. For SETI, in particular, this means that over the next two-dozen-years, the ATA will get a thousand times more data than has been accumulated in the past 45 years.
The ATA uses mass-produced, 20-foot diameter radio dishes and commercial telecommunications technologies combined with an innovative receiver design, and state-of-the-art digital signal processing technology. Working together, these small dishes create a telescope with a wide field of view ideally suited to rapidly surveying the sky. The layout of the 42 dishes was created by a computer model and is optimized to provide high quality radio imagery of the sky. The ATA can also filter out noise from man-made interference that in many radio telescopes would render much of the data unusable. The array can be easily upgraded as new advances in computer or telecommunications technology become available.
The total cost of the project to date, including research, development and construction costs for the array and the necessary radio astronomy and SETI signal detectors, is $50 million. The first phase of this project was funded through generous grants from the Paul G. Allen Family Foundation totaling $25 million. UC Berkeley, the SETI Institute, the National Science Foundation, Xilinx, Nathan Myhrvold, Greg Papadopoulos, and other corporations and individual donors contributed additional funding. Both UC Berkeley and the SETI Institute are engaging in additional fundraising efforts to complete the full 350-dish array.
The full 350-dish array, when completed in approximately three years, will have unprecedented research capabilities. Capitalizing on constant advancements in computer technology, the ATA will be manufactured at a fraction of the cost of traditional instruments. The ATA team is prepared to install more dishes as additional funding is secured.
Note: This story has been adapted from material provided by SETI Institute.

Fausto Intilla

www.oloscience.com

Astronomers Get Their Hands Dirty As They Lift The Veil On Galactic Dust

Source:

http://www.sciencedaily.com/releases/2007/10/071012105824.htm

Science Daily — There is more to a grain of dust than meets the eye, at least for astronomers as they attempt to probe deeper into distant galaxies. Until now dust has been a nuisance because it has obscured galaxies, and the stars within them, by absorbing the radiation they emit. But more recently dust has started to present opportunities because it emits radiation itself as a consequence of being heated up by nearby stars. Aided by new observing instruments and sophisticated computer software, this radiation enables astronomers to reconstruct what lies behind the dust. Furthermore the dust itself plays a vital role in star formation within galaxies.

The stage was set for dramatic advances in the study of galactic dust in a recent workshop funded by the European Science Foundation (ESF) 's Exploratory Workshop. The big breakthrough is the ability to detect the dust at much higher resolution from its infrared radiation, according to Simone Bianchi, co-convenor of the ESF workshop. "It has been possible to do this since the eighties, but the new instruments have a higher sensitivity," said Bianchi.
At the same time new computer models are making it possible to work out the structure of the galaxy lying behind the dust, even though it cannot be observed directly at any wavelength. The key here is that the dust is acting as a relay for radiation emitted by the stars behind it. The dust absorbs high energy radiation from the stars and then heats up as a result. It then re-emits in the infra red waveband, which can now be detected with sensitive new instruments.
Plans were made at the workshop to use the European Space Agency's new infrared space telescope called Herschel, which will be launched in 2008 and be capable of detecting infrared radiation emitted by distant galactic dust. "The new instruments will allow us to detect dust associated with less dense regions of the interstellar medium," said Bianchi.
Astronomers also hope to learn more about the role played by dust in star formation. As Bianchi pointed out, there is a well established connection between the dust and the gas from which stars are formed. But the detailed relationship is unknown, and will require knowledge about the dust itself, in particular its molecular structure and lifecycle.
The ESF workshop focused mainly on spiral galaxies, because these are heavily obscured by dust. Galaxies are split into three categories by their structure, spiral, elliptical, and irregular. There is less dust in elliptical galaxies, while irregular galaxies are more difficult to model because they lack any orderly structure. "Spiral galaxies can be modelled in a more direct way because of their relatively simple geometry," said Bianchi. "However, recent comparison with observations of dust emission has shown that models may need a higher degree of complexity. This can be achieved now with the advances in computational facilities."
The ESF workshop was well timed to help Europe exploit the full potential of the data that will be obtained from the new instruments. It has already brought together the relevant European groups specialising in spiral galaxies and modelling dust, providing the platform for major advances in the field.
The workshop, held in Ghent, Belgium in May 2007, brought together 29 researchers from 10 different countries. Each year, ESF supports approximately 50 Exploratory Workshops across all scientific domains. These small, interactive group sessions are aimed at opening up new directions in research to explore new fields with a potential impact on developments in science.
Note: This story has been adapted from material provided by European Science Foundation.

Fausto Intilla

www.oloscience.com

New Isotope Molecule May Add To Venus' Greenhouse Effect

Source:

http://www.sciencedaily.com/releases/2007/10/071010130150.htm

Science Daily — Planetary scientists on both sides of the Atlantic have tracked down a rare molecule in the atmospheres of both Mars and Venus. The molecule, an exotic form of carbon dioxide, could affect the way the greenhouse mechanism works on Venus.

The discovery is being announced at the annual meeting of the American Astronomical Society's Division of Planetary Sciences in Orlando, Florida. Its presence could affect the way the greenhouse mechanism works on Venus. The mystery began back in April 2006, soon after ESA's Venus Express arrived at the second planet in the Solar System.
A European team including members from France, Belgium and Russia lead by Jean-Loup Bertaux, Service d'Aeronomie du CNRS, France and Ann-Carine Vandaele, Institut d'Aeronomie Spatiale de Belgique, were using their Infrared Atmospheric Spectrometer (SOIR) instrument to measure solar occultations.
To do this, the instrument watches the Sun set behind Venus, allowing the scientists to study the way specific wavelengths of light are absorbed by the planet's atmosphere. These wavelengths and the level of absorption then give away the identity and amount of gases in the atmosphere.
The team saw an unidentified signature at 3.3 micrometres in the mid-infrared region of the spectrum. "It was conspicuous and systematic, increasing with depth in the atmosphere during the occultation, so we knew it was real," says Bertaux.
The team kept their discovery confidential as they attempted to identify the molecule responsible. They thought at first that it must be an organic molecule. These molecules contain carbon and hydrogen. However, none of the known organic molecules fitted well with the observations.
Then, in December 2006, Mike Mumma of NASA's Goddard Space Flight Center, Maryland, enquired whether the SOIR team was seeing anything special on Venus at 3.3 microns. He had discovered an unidentified spectral signature at that wavelength using telescopes on Hawaii pointing at Mars. The two teams compared the absorption signatures: they were identical.
This was a big clue. Both the atmospheres of Mars and Venus are composed of 95% carbon dioxide, although Venus's atmosphere is much thicker than the one at Mars. The American team suggested that the signature could be coming from an isotope of carbon dioxide, where one oxygen atom is 'normal', with eight protons and eight neutrons, while the other has eight protons and ten neutrons. Such an isotope makes up about 1% of carbon dioxide on Earth; the rest contains two normal oxygen atoms.
However, no one had previously seen the molecule absorb at 3.3 micrometres. An investigation by three independent groups, one led by Mumma in America; Sergei Tashkun and Valery Perevalov at Tomsk State University, Russia; and Richard Dahoo at Service d'Aéronomie du CNRS, France, all came to the same conclusion. The signature could be caused by a rare transition only possible in the isotope.
The different weights of the oxygen atoms allow the molecule to alter its vibration in two ways simultaneously, whereas normal molecules can only change one state at a time.
This rare transition allows it to absorb even more energy and so contribute even more to the greenhouse effect on Venus. On Earth, however, there is 250 000 times less carbon dioxide so its additional contribution to our greenhouse effect will be small.
Note: This story has been adapted from material provided by European Space Agency.

Fausto Intilla

www.oloscience.com

Dusty Winds Bursting Out Of Black Holes May Have Seeded Planets, Life

Source:

http://www.sciencedaily.com/releases/2007/10/071010125734.htm

Science Daily — The hit song that proclaimed, "All we are is dust in the wind," may have some cosmic truth to it. New findings from NASA's Spitzer Space Telescope suggest that space dust -- the same stuff that makes up living creatures and planets -- was manufactured in large quantities in the winds of black holes that populated our early universe.

The findings are a significant new clue in an unsolved mystery: where did all the dust in the young universe originate?
"We were surprised to find what appears to be freshly made dust entrained in the winds that blow away from supermassive black holes," said Ciska Markwick-Kemper of the University of Manchester, U.K. Markwick-Kemper is lead author of a new paper appearing in an upcoming issue of the Astrophysical Journal Letters. "This could explain where the dust came from that was needed to make the first generations of stars in the early universe."
Space dust is essential to the formation of planets, stars, galaxies and even life as we know it. The dust in our corner of the universe was piped out by dying stars that were once a lot like our sun. But, when the universe was less than a tenth of its present age of 13.7 billion years, sun-like stars hadn't been around long enough to die and make dust. So, what produced the precious substance back when the universe was just a toddler?
Theorists have long-postulated that short-lived, massive exploding stars, or supernovae, might be the source of this mysterious dust, while others have proposed that a type of energetic, growing supermassive black hole, called a quasar, could be a contributing factor. A quasar consists of a supermassive black hole surrounded by a dusty doughnut-shaped cloud that feeds it. Theoretically, dust could form in the outer portion of the winds that slowly blow away from this doughnut cloud.
"Quasars are like the Cookie Monster," said co-author Sarah Gallagher of the University of California at Los Angeles, who is currently a visiting astronomer at the University of Western Ontario, Canada. "They are messy eaters, and they can consume less matter than they spit out in the form of winds."
Nobody has found conclusive proof that either quasar winds or supernovae can create enough dust to explain what is observed in the early universe. Markwick-Kemper and her team decided to test the former theory and investigate a quasar, called PG2112+059, located in the center of a galaxy about 8 billion light-years way. Although this particular quasar is not located in the early universe, because it is closer, it is an easier target for addressing the question of whether quasars can make dust. The team used Spitzer's infrared spectrograph instrument to split apart infrared light from the quasar and look for signs of various minerals.
They found a mix of the ingredients that make up glass, sand, marble and even rubies and sapphires. While the mineral constituting glass was expected, the minerals for sand, marble and rubies were a surprise. Why? These minerals are not typically detected floating around galaxies, suggesting they could have been freshly formed in the winds rushing away from the quasar.
For instance, the ingredient that makes up sand, crystalline silicate, doesn't survive for long free-floating in space. Radiation from stars zaps the minerals back to an amorphous, glass-like state. The presence of crystalline silicate therefore suggests something -- possibly the quasars winds -- is churning out the newly made substance.
Markwick-Kemper and her team say the case of the missing dust is not firmly shut. They hope to study more quasars for further evidence of their dust-making abilities. Also, according to the astronomers, quasars may not be the only source of dust in the early universe. "Supernovae might have been more important for creating dust in some environments, while quasars were more important in others," said Markwick-Kemper. "For now, we are very excited to have identified the different species of dust in a quasar billions of light-years away."
Other authors of this paper include Dean Hines of the Space Science Institute, Boulder, Colo., and Jeroen Bouwman of the Max Planck Institute for Astronomy, Heidelberg, Germany. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Jim Houck of Cornell.
Note: This story has been adapted from material provided by NASA/Spitzer Space Telescope.

Fausto Intilla

www.oloscience.com

Pluto-bound Spacecraft Sees Changes In Jupiter System

Source:

http://www.sciencedaily.com/releases/2007/10/071009164110.htm

Science Daily — The voyage of NASA’s Pluto-bound New Horizons spacecraft through the Jupiter system earlier this year provided a bird’s-eye view of a dynamic planet that has changed since the last close-up looks by NASA spacecraft.

New Horizons passed Jupiter on Feb. 28, riding the planet’s gravity to boost its speed and shave three years off its trip to Pluto. It was the eighth spacecraft to visit Jupiter – but a combination of trajectory, timing and technology allowed it to explore details no probe had seen before, such as lightning near the planet’s poles, the life cycle of fresh ammonia clouds, boulder-size clumps speeding through the planet’s faint rings, the structure inside volcanic eruptions on its moon Io, and the path of charged particles traversing the previously unexplored length of the planet’s long magnetic tail.
“The Jupiter encounter was successful beyond our wildest dreams,” says New Horizons Principal Investigator Alan Stern, of NASA Headquarters, Washington. “Not only did it prove out our spacecraft and put it on course to reach Pluto in 2015, it was a chance for us to take sophisticated instruments to places in the Jovian system where other spacecraft couldn’t go, and to return important data that adds tremendously to our understanding of the solar system’s largest planet and its moons, rings and atmosphere.”
The New Horizons team presents its latest and most detailed analyses of that data today at the American Astronomical Society’s Division for Planetary Sciences meeting in Orlando, Fla., and in a special section of the Oct. 12 issue of the journal Science. The section includes nine technical papers written by New Horizons team members and collaborators.
From January through June, New Horizons’ seven science instruments made more than 700 separate observations of the Jovian system – twice the activity planned at Pluto – with most of them coming in the eight days around closest approach to Jupiter. “We carefully selected observations that complemented previous missions, so that we could focus on outstanding scientific issues that needed further investigation,” says New Horizons Jupiter Science Team Leader Jeff Moore, of NASA Ames Research Center, Moffett Field, Calif. “The Jupiter system is constantly changing and New Horizons was in the right place at the right time to see some exciting developments.”
Jovian weather was high on the list, as New Horizons’ visible light, infrared and ultraviolet remote-sensing instruments probed Jupiter’s atmosphere for data on cloud structure and composition. They saw clouds form from ammonia welling up from the lower atmosphere and heat-induced lighting strikes in the polar regions – the first polar lighting ever observed beyond Earth, demonstrating that heat moves through water clouds at virtually all latitudes across Jupiter. They made the most detailed size and speed measurements yet of “waves” that run the width of planet and indicate violent storm activity below. Additionally, New Horizons snapped the first close-up images of the Little Red Spot, a nascent storm about half the size of Jupiter’s larger Great Red Spot and about 70 percent of Earth’s diameter, gathering new information on storm dynamics.
Under a range of lighting and viewing angles, New Horizons also captured the clearest images ever of the tenuous Jovian ring system. In them, scientists spotted clumps of debris that may indicate a recent impact inside the rings, or some more exotic phenomenon; movies made from New Horizons images also offer an unprecedented look at ring dynamics, with the tiny inner moons Metis and Adrastea shepherding the materials around the rings. A search for smaller moons inside the rings – and possible new sources of the dusty material – found no bodies wider than a kilometer.
The mission’s investigations of Jupiter’s four largest moons focused on Io, the closest to Jupiter and whose active volcanoes blast tons of material into the Jovian magnetosphere (and beyond). New Horizons spied 11 different volcanic plumes of varying size, three of which were seen for the first time and one – a spectacular 200-mile-high eruption rising above the volcano Tvashtar – that offered an unprecedented opportunity to trace the structure and motion of the plume as it condensed at high altitude and fell back to the moon’s surface. In addition, New Horizons spotted the infrared glow from at least 36 Io volcanoes, and measured lava temperatures up to 1,900 degrees Fahrenheit, similar to many terrestrial volcanoes.
New Horizons’ global map of Io’s surface backs the moon’s status as the solar system’s most active body, showing more than 20 geological changes since the Galileo Jupiter orbiter provided the last close-up look in 2001. The remote imagers also kept watch on Io in the darkness of Jupiter’s shadow, noting mysterious glowing gas clouds above dozens of volcanoes. Scientists suspect that this gas helps to resupply Io’s atmosphere.
New Horizons' flight down Jupiter's magnetotail gave it an unprecedented look at the vast region dominated by the planet's strong magnetic field. Looking specifically at the fluxes of charged particles that flow hundreds of millions of miles beyond the giant planet, the New Horizons particle detectors saw evidence that tons of material from Io’s volcanoes move down the tail in large, dense, slow-moving blobs. By analyzing the observed variations in particle fluxes over a wide range of energies and scales, New Horizons scientists are exploring how the volcanic gases from Io are ionized, trapped and energized by Jupiter's magnetic field, then ultimately ejected from the system.
Designed, built and operated by the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., New Horizons lifted off from Cape Canaveral Air Force Station, Fla., in January 2006. The fastest spacecraft ever launched, it needed just 13 months to reach Jupiter. New Horizons is now about halfway between the orbits of Jupiter and Saturn, more than 743 million miles (1.19 billion kilometers) from Earth. It will fly past Pluto and its moons in July 2015 before heading deeper into the Kuiper belt of icy rocky objects on the planetary frontier.
New Horizons is the first mission in NASA’s New Frontiers Program of medium-class spacecraft exploration projects. Stern leads the mission and science team as principal investigator; APL manages the mission for NASA’s Science Mission Directorate. The mission team also includes Southwest Research Institute, Ball Aerospace Corporation, the Boeing Company, NASA Goddard Space Flight Center, NASA Jet Propulsion Laboratory, Stanford University, KinetX Inc. (navigation team), Lockheed Martin Corporation, University of Colorado, the U.S. Department of Energy, and a number of other firms, NASA centers, and university partners.
Note: This story has been adapted from material provided by Johns Hopkins University.

Fausto Intilla

www.oloscience.com

Cassini Is On The Trail Of A Runaway Mystery

Source:

http://www.sciencedaily.com/releases/2007/10/071008145004.htm

Science Daily — 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.

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.
New Iapetus images, temperature maps and other visuals on Iapetus are available at: http://saturn.jpl.nasa.gov/ and http://www.nasa.gov/cassini .
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.
Note: This story has been adapted from material provided by NASA/Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Multiwavelength Images Of Distant Universe Now Available On Google Sky

Source:

http://www.sciencedaily.com/releases/2007/10/071003130840.htm

Science Daily — A massive project to map a distant region of the Universe in multiple wavelengths--from x-rays through ultraviolet, visible, infrared, and radio waves--is currently releasing its data to both fellow scientists and the general public. It is the first data release from the AEGIS survey and the first release of multiwavelength data to take advantage of the capabilities of Google Sky, a new feature of Google Earth.

AEGIS--the All-wavelength Extended Groth Strip International Survey--combines the efforts of nearly 100 researchers from around the world observing the same small region of sky in all available wavelengths of the electromagnetic spectrum. The target area, called the Extended Groth Strip, covers an area the width of four full moons that is a hop, skip and jump from the end of the Big Dipper's handle. The AEGIS region has now been surveyed more intensively and with more telescopes than any other region of the sky.
"We are still sorting through this treasure trove to discover the many gems of information it contains," said Sandra Faber, University Professor and chair of astronomy and astrophysics at the University of California, Santa Cruz. Faber worked with Jeffrey Newman of the University of Pittsburgh, Shui Kwok of the W. M. Keck Observatory in Hawaii, UCSC graduate student Genevieve Graves, and many other members of the AEGIS team to coordinate the data release through Google Sky.
"We are looking back to a time when the universe was more than half its current age and when galaxies were forming most of their stars," says Professor Kirpal Nandra, from the Department of Physics and who is leading the project from Imperial College London. He added: "With the X-ray images we are looking at black holes, which are at the centre of galaxies, to try to work out how the growth of black holes is linked to the growth of the galaxy itself."
"It is clear that serving astronomical data through Google Sky is going to revolutionize the way astronomers communicate, both among themselves and with the public," Faber said. "AEGIS is proud and pleased to be the pathfinder dataset for Google Sky's new multiwavelength capabilities."
Color images from four different satellite telescopes, as well as numerous data catalogs, from x-ray to radio wavelengths, giving brightnesses and distances of tens of thousands of galaxies are now available. Google Earth's new Sky feature provides a fast and powerful access tool for astronomical data similar to what the popular Google Earth software has provided for terrestrial data.
"AEGIS images projected onto the celestial sphere show how it would look with infrared, ultraviolet, or x-ray eyes," Faber said. "Some galaxies look brighter at certain wavelengths than others, which carries important information about their composition and the processes occurring within them."
The rapid browsing abilities of Google Sky provide a new way to compare many views of a single galaxy or a set of galaxies instantly. For researchers, it is a powerful tool for exploring AEGIS's massive data sets. The AEGIS collaboration is also making all of its data available on its website, so that researchers can download it directly.
Of the four color images in the first AEGIS data release, the most detailed is a visible-light image stitched together from 63 separate pointings of the Hubble Space Telescope. This image forms the base map in Google Sky. Stretching twice the width of the full Moon, it is the largest unbroken color mosaic ever made with Hubble and contains images of approximately 50,000 faraway galaxies. Light has traveled for more than 10 billion years from the most distant ones, giving us pictures of them as they looked long ago, more than three-quarters of the way back to the Big Bang. The exquisite detail of the Hubble images shows infant and adolescent galaxies as they began to form.
The second image shows the same galaxies through the ultraviolet eyes of NASA's Galaxy Evolution Explorer (GALEX) satellite. Ultraviolet wavelengths are shorter and bluer than those of visible light. Massive, hot young stars that are just forming produce ultraviolet light in abundance. Brightness in the GALEX image therefore provides a measure of the rate at which each galaxy is forming stars. Galaxies that contain relatively few hot, young stars or that are obscured by either their own dust or diffuse gas along our line of sight will appear redder in the GALEX image.
The third view is a mosaic of images taken with the Infrared Array Camera on NASA's Spitzer Space Telescope, the last mission in NASA's Great Observatory series. Near-infrared brightness is closely related to the total number of stars in a galaxy, while the colors of a galaxy as seen through infrared eyes reveal information on both its contents (stars and dust) and its distance from us.
The fourth image was produced with data from NASA's Chandra X-ray Observatory. In the objects seen by Chandra, highly energetic x-ray radiation has been produced when gas is spiralling into a supermassive black hole, like those believed to lie at the center of almost every galaxy. Many of the x-ray-emitting objects lie buried within otherwise normal-looking galaxies. In the x-ray images, the bluest objects are the ones most obscured by gas within their host galaxies.
In the objects seen by Chandra, X-ray radiation has been produced when gas is spiralling into a super massive black hole, like those believed to lie at the centre of almost every galaxy. Many of the X-ray emitting objects lie buried within otherwise normal-looking galaxies. In these X-ray images, the bluest objects are the ones most obscured by gas within their host galaxies, according to researchers at Imperial College in London.
In combination, these images simultaneously measure the sizes and shapes of galaxies, their current rates of star formation, the total number of stars each galaxy has already formed, and the rate at which a black hole at its center is actively accreting matter. All of this information provides separate clues to help scientists understand the evolution of galaxies over the past 10 billion years.
These images from space-based telescopes are tied together by the spectra of nearly 15,000 AEGIS galaxies taken with the Keck II Telescope in Hawaii as part of the DEEP2 Galaxy Redshift Survey, led by Faber and Marc Davis of UC Berkeley. Among other information, these spectra enable astronomers to determine distances to these objects, which is crucial for distinguishing small galaxies in the foreground from giant galaxies that appear faint because they are so far away. Once they have determined the distance to a galaxy, astronomers know how far back in time light left it. The most distant galaxies in the AEGIS survey are seen as they looked only a few billion years after the Big Bang.
With the Sky feature in Google Earth, users can pan and zoom around all of these pictures of the sky to select individual galaxies for closer inspection. By adjusting the transparency of each image, the user can focus on only one of the AEGIS images at a time, or look at a combination (e.g., the GALEX image superimposed on Hubble). Clicking on galaxies in AEGIS catalogs brings up their distances and intrinsic properties. A further mouse click links the user to the Keck spectrum and additional information being used for AEGIS science studies.
This first data release from AEGIS is only the first step. Later releases will feature images taken at far-infrared and radio wavelengths. A master catalog is being prepared that combines information from all of AEGIS's many views of the sky. As future images are prepared, they and the growing data catalogs will all be linked through Google Sky.
The AEGIS web site gives more information about the survey, science results to date, and links to additional images and data that can be downloaded. The many windows on the universe provided by AEGIS have already produced a variety of new results on the evolution of galaxies, and many more new findings from the AEGIS team will appear soon, according to Newman.
"With this public release of both interactive images and the underlying data catalogs, the full astronomical community will now be able to take advantage of this powerful new dataset," he said.
The AEGIS teams that contributed images and data for this release include the Hubble team led by Marc Davis of UC Berkeley; the Chandra team lead by Kirpal Nandra of Imperial College, London; the Spitzer team led by Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics; and the GALEX team led by Chris Martin of the California Institute of Technology. Funding for the AEGIS collaboration was provided by the National Science Foundation and NASA.
Images are available at: http://earth.google.com/gallery/index.html
Note: This story has been adapted from material provided by University of California, Santa Cruz.

Fausto Intilla

www.oloscience.com

Dark Matter Of The Universe Has A Long Lifetime

Source:

http://www.sciencedaily.com/releases/2007/10/071001112906.htm

Science Daily — New research from the Niels Bohr Institute presents new information that adds another piece of knowledge to the jigsaw puzzle of the dark mystery of the universe -- dark matter.

The universe consists not just of visible celestial bodies, stars, planets and galaxies. It also has a mystical fellow player -- dark matter. The astronomers can measure that the dark matter exists in big quantities but no one knows what it is, nobody has seen it. It does not emit light and it does not reflect light. It is invisible. It is a mystery and the researchers have many theories.
The dark matter has caused the researchers headaches for decades since it was detected in the 1970s, and there is intense research into the phenomena. It is invisible but it has got mass, and thus it has got gravitation that can be measured. By analysing the galaxies it is possible to weigh them, and it turns out that by far the greatest matter of the collective mass of the galaxy is dark matter.
Just like stars get together in galaxies, the galaxies get together in clusters of galaxies of up to several thousand galaxies. The astrophysicist Signe Riemer-Sørensen, PhD student at the Niels Bohr Institute, has analysed two clusters of galaxies that collide.
Colliding clusters of galaxies
When the two clusters of galaxies meet neither the galaxies nor the dark matter collide. However, about 12 per cent of the mass of the cluster of galaxies consists of huge clouds of gas and dust and these clouds collide. The gas clouds are hot and emit x-ray that can be observed, and it is possible to see how the clouds are actually pushed out of the two clusters of galaxies at the collision. When the clouds of gas collide they become even hotter and emit more x-ray so that a whole chock front of warn gas is generated.
Observations indicate that the dark matter can be a new and still undetected type of particle. Among the suggestions for the dark matter, are particles that when they decay they emit x-ray. One is the so called axions that are particles which is explained in theories with extra dimensions. So to be able to look for x-ray from dark matter the researchers are looking in places where there is a big concentration of dark matter, but no gas. Such places are found in the two colliding clusters of galaxies where the gas clouds have been pushed out at the collision.
Signe Riemer-Sørensen has analysed the one of the two clusters of galaxies that are in the process of colliding. The analyses show that it is a very heavy cluster with many galaxies, and measurement of the gravitation show that there is a very big amount of dark matter, up to 85 per cent of the collective mass. However, no x-ray of any consequence was measured.
When the dark matter does not emit significant x-ray it is possible to calculate an upper limit to how quickly the particles decay and thus calculate their lifetime. The result is that if axions are to be the dark matter they must have a life span that is longer that 3.000.000 billion years. In that case there is not very much dark matter that has decayed yet if it was formed 13.7 billion years ago. The conclusion is that dark matter has a very, very long lifetime.
The research has just been published in the scientific journal Physical Review Letters.
Note: This story has been adapted from material provided by University of Copenhagen.

Fausto Intilla

www.oloscience.com

Earth-like Planet Forming In Nearby Star System, Astronomers Believe

Source:

http://www.sciencedaily.com/releases/2007/10/071003130744.htm

Science Daily — An Earth-like planet is likely forming 424 light-years away in a star system called HD 113766, say astronomers using NASA's Spitzer Space Telescope.

Scientists have discovered a huge belt of warm dust – enough to build a Mars-size planet or larger – swirling around a distant star that is just slightly more massive than our sun.
The dust belt, which they suspect is clumping together into planets, is located in the middle of the system's terrestrial habitable zone. This is the region around a star where liquid water could exist on any rocky planets that might form. Earth is located in the middle of our sun's terrestrial habitable zone.
At approximately 10 million years old, the star is also at just the right age for forming rocky planets.
"The timing for this system to be building an Earth is very good," says Dr. Carey Lisse, of the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. "If the system was too young, its planet-forming disk would be full of gas, and it would be making gas-giant planets like Jupiter instead. If the system was too old, then dust aggregation or clumping would have already occurred and all the system's rocky planets would have already formed."
According to Lisse, the conditions for forming an Earth-like planet are more than just being in the right place at the right time and around the right star – it's also about the right mix of dusty materials.
Using Spitzer's infrared spectrometer instrument, he determined that the material in HD 113766 is more processed than the snowball-like stuff that makes up infant solar systems and comets, which are considered cosmic "refrigerators" because they contain pristine ingredients from the early solar system. However, it is also not as processed as the stuff found in mature planets and the largest asteroids. This means the dust belt must be in a transitional phase, when rocky planets are just beginning to form.
How do scientists know the material is more processed than that of comets? From missions like NASA's Deep Impact – in which an 820-pound impactor spacecraft collided with comet Tempel 1 – scientists know that early star systems contain a lot of fragile organic material. That material includes polycyclic aromatic hydrocarbons (carbon-based molecules found on charred barbeque grills and automobile exhaust on Earth), water ice, and carbonates (chalk). Lisse says that HD 113766 does not contain any water ice, carbonates or fragile organic materials.
From meteorite studies on Earth, scientists also have a good idea of what makes up asteroids – the more processed rocky leftovers of planet formation. These studies tell us that metals began separating from rocks in Earth's early days, when the planet's body was completely molten. During this time, almost all the heavy metals fell to Earth's center in a process called "differentiation." Lisse says that, unlike planets and asteroids, the metals in HD 113766 have not totally separated from the rocky material, suggesting that rocky planets have not yet formed.
"The material mix in this belt is most reminiscent of the stuff found in lava flows on Earth. I thought of Mauna Kea material when I first saw the dust composition in this system – it contains raw rock and is abundant in iron sulfides, which are similar to fool's gold," says Lisse, referring to a well-known Hawaiian volcano.
"It is fantastic to think we are able to detect the process of terrestrial planet formation. Stay tuned — I expect lots more fireworks as the planet in HD113766 grows," he adds.
Lisse's article, Circumstellar Dust Created by Terrestrial Planet Formation in HD 113766, will be published in an upcoming issue of Astrophysical Journal. He will also present his findings at the upcoming meeting of the American Astronomical Society Division for Planetary Sciences in Orlando, Fla. Lisse's research was funded through a Johns Hopkins Applied Physics Laboratory Stuart S. Janney Fellowship and a Spitzer Space Telescope guest observer grant.
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.
The University of Maryland is responsible for overall Deep Impact mission science, and project management is handled by JPL.
Note: This story has been adapted from material provided by Johns Hopkins University.

Fausto Intilla

www.oloscience.com

Disc Of Silicates Found In Heart Of Magnificent Ant Nebula

Source:

http://www.sciencedaily.com/releases/2007/09/070927113205.htm

Science Daily — Using ESO's Very Large Telescope Interferometer and its unique ability to see small details, astronomers have uncovered a flat, nearly edge-on disc of silicates in the heart of the magnificent Ant Nebula. The disc seems, however, too 'skinny' to explain how the nebula got its intriguing ant-like shape.
The Ant Nebula is one of the most striking planetary nebulae known. Planetary nebulae - whose name arises because most are spherical and looked like planets when they were first discovered through older, less powerful telescopes - are glowing structures of gas cast off by solar-like stars at the ends of their lives. The morphology of the Ant Nebula - a bright core, three nested pairs of bipolar lobes and a ring-like outflow - is so unique that it was nicknamed the 'Chamber of Horrors' of planetary nebulae in the late 1950s.
But how can a spherical star produce such complex structures? The answer, many astronomers think, requires understanding of the discs surrounding the central star. By their nature, these discs bear witness to the phenomena that lead to the asymmetrical structures of planetary nebulae.
"The challenge is to actually detect these discs," explains team leader Olivier Chesneau, from the Observatoire de la Côte d'Azur, France. "Most astronomical instruments do not have a sharp enough view to find, let alone study them. The Very Large Telescope Interferometer however, with its exceptionally high spatial resolution, is a powerful disc-hunter."
The disc of the Ant Nebula, which cannot be detected with a single 8.2-m VLT Unit Telescope, was uncovered in the interferometric mode where two 8.2-m Unit Telescopes were used to combine light, through the MID-infrared Interferometric instrument (MIDI). The observations reveal a flat, nearly edge-on disc whose major axis is perpendicular to the axis of the bipolar lobes.
The disc extends from about 9 times the mean distance between the Earth and the Sun (9 Astronomical Units or 9 AU) to more than 500 AU. At the distance of the Ant Nebula, this corresponds to having detected structures that subtend an angle of only 6 milli-arcseconds. This is similar to distinguishing a two-storey building on the Moon.
The dust mass stored in the disc appears to be only one hundred thousandth the mass of the Sun and is a hundred times smaller than the mass found in the bipolar lobes.
"We must therefore conclude that the disc is too light to have a significant impact on the outflowing material and cannot explain the shape of the Ant Nebula", says Chesneau. "Instead, it looks more like this disc is some remnant of the material expelled by the star."
The observations also provide unquestionable evidence that the disc is primarily composed of amorphous silicate. "This," says Chesneau, "most likely indicates that the disc is young, perhaps as young as the planetary nebula itself."
The astronomers favour the possibility that the large quantity of material in the lobes was propelled by several large-scale events, triggered with the help of a cool stellar companion. The solution of the mystery thus resides in the core of the system, and requires better characterisation of the hot central star and its putative companion, currently hidden from our view by the dusty disc.
The results are presented in a Letter to the Editor published by the research journal Astronomy and Astrophysics ("A silicate disk in the heart of the Ant" by O. Chesneau et al.).
The team is composed of O. Chesneau and A. Spang (Observatoire de la Côte d'Azur, France), F. Lykou, E. Lagadec, and A.A. Zijlstra (University of Manchester, UK), B. Balick (University of Washington, Seattle, USA), M. Matsuura (NAOJ, Tokyo, Japan), N. Smith (University of California, USA), and S. Wolf (Max-Planck-Institute for Astronomy, Heidelberg, Germany).
Note: This story has been adapted from material provided by ESO.

Fausto Intilla
www.oloscience.com

Into The Chrysalis: VLT Interferometer Detects Disc Around Aged Star

Source:

http://www.sciencedaily.com/releases/2007/09/070927113202.htm

Science Daily — A team of European astronomers has used ESO's Very Large Telescope Interferometer and its razor-sharp eyes to discover a reservoir of dust trapped in a disc that surrounds an elderly star. The discovery provides additional clues about the shaping of planetary nebulae.

In the last phases of their life, stars such as our Sun evolve from a red giant which would engulf the orbit of Mars to a white dwarf, an object that is barely larger than the Earth. The transition is accomplished by the shedding of a huge envelope of gas and dust that sparkles in many colours, producing a most spectacular object: a planetary nebula. The celestial chrysalis becomes a cosmic butterfly.
This metamorphosis, rapid in terms of the star's lifetime, is rather complex and poorly understood. In particular, astronomers want to understand how a spherical star can produce a great variety of planetary nebulae, some with very asymmetrical shapes.
A team of scientists therefore embarked upon the study of a star which is presently on its way to becoming a cosmic butterfly. The star, V390 Velorum, is 5000 times as bright as our Sun and is located 2,600 light-years away. It is also known to have a companion that accomplishes its ballet in 500 days.
Astronomers postulate that elderly stars with companions possess a reservoir of dust that is thought to play a lead role in the final chapters of their lives. The shape and structure of these reservoirs remain, however, largely unknown.
To scrutinize the object with great precision, the astronomers linked observations taken with ESO's powerful interferometric instruments, AMBER and MIDI, at the Very Large Telescope Interferometer. In particular, they combined, using AMBER, the near-infrared light of three of VLT's 8.2-m Unit Telescopes. "Only this triple combination of powerful telescopes allows us to pinpoint the position and the shape of the dusty reservoir on a milli-arcsecond scale," explains Pieter Deroo, lead-author of the paper that presents these results in the research journal Astronomy and Astrophysics.
These observations clearly demonstrate that the dust present around the star cannot be distributed in a spherical shell. "This shows that whatever mechanism is shaping asymmetric planetary nebulae is already present prior to the metamorphosis taking place," says Hans Van Winckel, member of the team.
The astronomers found indeed evidence for a disc extending from 9 Astronomical Units* to several hundreds of AU. "This disc is found around a star that is in a very brief phase of its life - just a blink of an eye over the star's lifespan of billions of years - but this phase is very important," says Deroo. "It is in this period that a huge morphological change occurs, leading to the creation of a planetary nebula," he adds.
The very high spatial resolution measurements allowed the astronomers to decouple the unresolved contribution of the central star from the resolved disc emission. Even the very inner structure of the disc as well as its orientation and inclination could be determined. The observations probe the physical nature of the disc and reveal that the dust in the inner rim is extremely hot and puffed up. The disc is circumbinary as it surrounds both stars.
Dust processing (coagulation, crystallisation) is found to be very efficient in this circumbinary disc, despite the rather short evolutionary timescales involved. The disc around this evolved object is very similar to those around young stellar objects, in which planets are formed.
"The combination of MIDI and AMBER on ESO's VLTI is an extremely powerful and perhaps unique tool to study the geometry of the material around stars," concludes Van Winckel.
It looks like it is the season for disc 'hunting': the detection of a dusty disc in the notable Ant Nebula was also just announced (see ESO 42/07).
The results presented here are reported in a Letter to the Editor to appear in the research journal Astronomy and Astrophysics ("AMBER and MIDI interferometric observations of the post-AGB binary IRAS 08544-4431: the circumbinary disc resolved", by P. Deroo et al.).
The team includes Pieter Deroo, Bram Acke, Tijl Verhoelst, and Hans Van Winckel (K. U. Leuven, Belgium), Carsten Dominik (University of Amsterdam, the Netherlands), and Eric Tatulli (INAF-Observatorio di Arcetri, Firenze, Italy).
*One Astronomical Unit (AU) is the mean distance between the Earth and the Sun. It corresponds to 149.6 million kilometres. For comparison, Saturn is 10 AU away from the Sun.
Note: This story has been adapted from material provided by European Organisation For Astronomical Research In The Southern Hemisphere.

Fausto Intilla

www.oloscience.com