CSIRO Telescope Spots Mega-Star Cradle

Mid-infrared image of BYF 73 from NASA's Spitzer Space Telescope. The yellowish wisps to the right are remnants of gas that have been heated and are being driven off by the massive young stars within them (seen in blue). The large-scale collapse of colder gas to form a massive cluster is centred around the bright stars just to the left of the heated wisps. Image credit - NASA/JPL-Caltech

Using a CSIRO radio telescope, an international team of researchers has caught an enormous cloud of cosmic gas and dust in the process of collapsing in on itself - a discovery which could help solve one of astronomy's enduring conundrums: 'How do massive stars form?'

Dr Peter Barnes from the University of Florida says astronomers have a good grasp of how stars such as our Sun form from clouds of gas and dust, but for heavier stars - ten times the mass of the Sun or more - they are still largely in the dark, despite years of work.

"Astronomers are still debating the physical processes that can generate these big stars," Dr Barnes says.

"Massive stars are rare, making up only a few per cent of all stars, and they will only form in significant numbers when really massive clouds of gas collapse, creating hundreds of stars of different masses. Smaller gas clouds are not likely to make big stars."

Accordingly, regions in space where massive stars seem to be forming are also rare. Most are well over 1000 light-years away, making them hard to observe.

Using CSIRO's 'Mopra' radio telescope - a 22m dish near Coonabarabran, NSW - the research team discovered a massive cloud of mostly hydrogen gas and dust, three or more light-years across, that is collapsing in on itself and will probably form a huge cluster of stars.

Dr Stuart Ryder of the Anglo-Australian Observatory said the discovery was made during a survey of more than 200 gas clouds.

"With clouds like this we can test theories of massive star cluster formation in great detail."

The gas cloud, called BYF73, is about 8,000 light years away, in the constellation of Carina ("the keel") in the Southern sky.

Evidence for 'infalling' gas came from the radio telescope's detection of two kinds of molecules in the cloud - HCO+ and H13CO+. The spectral lines from the HCO+ molecules in particular showed the gas had a velocity and temperature pattern that indicated collapse.

Mopra Research Scientist at CSIRO Astronomy and Space Science, Dr Kate Brooks, said the Mopra telescope excels at giving a picture of the complex chemistry of cosmic gas clouds.

"Much of its time is used for large projects like this, and almost all Mopra projects are international collaborations."

The CSIRO telescope observations were confirmed by observations with the Atacama Submillimeter Telescope Experiment (ATSE) telescope in Chile.

The research team calculates that the gas is falling in at the rate of about three per cent of the Sun's mass every year - one of the highest rates known.

Follow-up infrared observations made with the 3.9-m Anglo-Australian Telescope (also near Coonabarabran, NSW) showed signs of massive young stars that have already formed right at the centre of the gas clump, and new stars forming.

Star-formation in the cloud was also evident in archival data from the Spitzer and MSX spacecraft, which observe in the mid-infrared.

Gas cloud BYF73 was found during a large-scale search for massive star-forming regions - the Census of High- and Medium-mass Protostars, or CHaMP. This is one of the largest, most uniform and least biased surveys to date of massive star-forming regions in our Galaxy.

Webb Telescope Passes Mission Design Review Milestone

NASA's Northrop Grumman-built James Webb Space Telescope has passed its most significant mission milestone to date, the Mission Critical Design Review, or MCDR. This signifies the integrated observatory will meet all science and engineering requirements for its mission.

"I'm delighted by this news and proud of the Webb program's great technical achievements," said Eric Smith, Webb telescope program scientist at NASA Headquarters in Washington.

"The independent team conducting the review confirmed the designs, hardware and test plans for Webb will deliver the fantastic capabilities always envisioned for NASA's next major space observatory. The scientific successor to Hubble is making great progress."

NASA's Goddard Space Flight Center, in Greenbelt, Md., manages the mission. Northrop Grumman, Redondo Beach, Calif., is leading the design and development effort.

"This program landmark is the capstone of seven years of intense, focused effort on the part of NASA, Northrop Grumman and our program team members," said David DiCarlo, sector vice president and general manager of Northrop Grumman Space Systems.

"We have always had high confidence that our observatory design would meet the goals of this pioneering science mission. This achievement testifies to that, as well as to our close working partnership with NASA."

The MCDR encompassed all previous design reviews including the Integrated Science Instrument Module review in March 2009; the Optical Telescope Element review completed in October 2009; and the Sunshield review completed in January 2010. The project schedule will undergo a review during the next few months.

The spacecraft design, which passed a preliminary review in 2009, will continue toward final approval next year.

The review also brought together multiple modeling and analysis tools. Because the observatory is too large for validation by actual testing, complex models of how it will behave during launch and in space environments are being integrated. The models are compared with prior test and review results from the observatory's components.

Although the MCDR approved the telescope design and gave the official go-ahead for manufacturing, hardware development on the mirror segments has been in progress for several years.

Eighteen primary mirror segments are in the process of cryo-polishing and testing at Ball Aerospace in Huntsville, Ala. Manufacturing on the backplane, the structure that supports the mirror segments, is well underway at Alliant Techsystems, or ATK, in Magna, Utah.

This month ITT Corp. in Rochester, N.Y., demonstrated robotic mirror installation equipment designed to position segments on the backplane. The segments' position will be fine-tuned to tolerances of a fraction of the width of a human hair. The telescope's sunshield moved into its fabrication and testing phase earlier this year.

The three major elements of Webb - the Integrated Science Instrument Module, Optical Telescope Element and the spacecraft itself - will proceed through hardware production, assembly and testing prior to delivery for observatory integration and testing scheduled to begin in 2012.

The Webb is the premier next-generation space observatory for exploring deep space phenomena from distant galaxies to nearby planets and stars.

The telescope will provide clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth. The telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

Where comets emit dust

This is a look at the comet Tempel 1 through a telescope. The active regions are responsible for the bright jets (left). With the help of their computer simulation the MPS-scientists can reconstruct the image seen from Earth (right).

Studying comets can be quite dangerous - especially from close up. Because the tiny particles of dust emitted into space from the so-called active regions on a comet's surface can damage space probes. Scientists from the Max Planck Institute for Solar System Research in Germany have now developed a computer model that can locate these regions using only the information available from Earth. The new method could help calculate a safe flight route for ESA's space probe Rosetta, which is scheduled to arrive at the comet Churyumov-Gerasimenko in 2014. (Astronomy & Astrophysics, 512, A60, 2010) A comet's nucleus is much more than an unvarying chunk of ice and dust. Under the Sun's influence, volatile substances such as water, carbon dioxide, and carbon monoxide are emitted from certain regions on its surface - the so-called active regions - carrying dust particles with a diameter of up to a few centimetres into space. Seen from Earth, these fountains of dust can be discerned as jets or spiral arms that surround the comet (see figure 1). These structures are embedded in a sheath of gas and dust called the coma that is produced by the more uniform activity of the overall surface.

"Pictures taken from Earth show the comet and its jets as a two-dimensional projection", explains Hermann Böhnhardt from the Max Planck Institute for Solar System Research (MPS). Where exactly the dust particles and gases originate from can not therefore be well identified.

In order to localize the active regions despite this problem, the MPS-researchers chose an indirect approach that for the first time also accounts for the three dimensional shape of the comet. "Until now, computer programs trying to find the active regions assumed the comet as a sphere or ellipsoid", explains Jean-Baptiste Vincent from MPS. Since in reality comets often have quite bizarre shapes, for many applications this approach is not good enough. The researchers therefore decided to take a standard approach: While watching a comet for an entire rotation period, changes in its luminance allow its true form to be calculated.

In a next step, the researchers fed their program with an initial assumption where the active regions might be located. Additionally they made an "educated guess" concerning the physical properties of the dust particles like size and initial velocity upon emission from the nucleus. As a result, the computer simulation delivers an image as it would be seen through a telescope on Earth. By comparing this with the actual image through a telescope the model can be refined step by step until simulation and actual image agree.

Already, the new method has passed its first test: The scientists could successfully apply it to the comet Tempel 1 that was the destination of NASA's Deep Impact Mission in 2005. "Even though ever since this mission we know where Tempel1's active regions are, we pretended not to", explains Vincent. For their computer program the scientists only used information that was available from Earth-base observations - apart from the nucleus shape model that was adopted from the mission results.

Next, the researchers intend to calculate the active regions of the comet Churyumov-Gerasimenko, the rendezvous target for ESA's Rosetta mission on which the Rosetta lander Philae will touch down in late 2014. The mission, to which MPS contributed many scientific instruments, has been on route to its destination beyond the orbit of Mars and the asteroid belt since 2004. In the crucial phase of the mission, the new method could help to determine a safe route for Rosetta through the cometary coma and maybe even find a suitable landing site.

Source: Max-Planck-Gesellschaft

World’s Biggest Eye on the Sky to be Located on Armazones, Chile

On 26 April 2010, the ESO Council selected Cerro Armazones as the baseline site for the planned 42-metre European Extremely Large Telescope (E-ELT). Cerro Armazones is a mountain at an altitude of 3060 metres in the central part of Chile’s Atacama Desert, some 130 kilometres south of the town of Antofagasta and about 20 kilometres from Cerro Paranal, home of ESO’s Very Large Telescope.

“This is an important milestone that allows us to finalise the baseline design of this very ambitious project, which will vastly advance astronomical knowledge,” says Tim de Zeeuw, ESO’s Director General. “I thank the site selection team for the tremendous work they have done over the past few years.”

ESO’s next step is to build a European extremely large optical/infrared telescope (E-ELT) with a primary mirror 42 metres in diameter. The E-ELT will be “the world’s biggest eye on the sky” — the only such telescope in the world. ESO is drawing up detailed construction plans together with the community. The E-ELT will address many of the most pressing unsolved questions in astronomy, and may, eventually, revolutionise our perception of the Universe, much as Galileo's telescope did 400 years ago. The final go-ahead for construction is expected at the end of 2010, with the start of operations planned for 2018.

The decision on the E-ELT site was taken by the ESO Council, which is the governing body of the Organisation composed of representatives of ESO’s fourteen Member States, and is based on an extensive comparative meteorological investigation, which lasted several years. The majority of the data collected during the site selection campaigns will be made public in the course of the year 2010.

Various factors needed to be considered in the site selection process. Obviously the “astronomical quality” of the atmosphere, for instance, the number of clear nights, the amount of water vapour, and the “stability” of the atmosphere (also known as seeing) played a crucial role. But other parameters had to be taken into account as well, such as the costs of construction and operations, and the operational and scientific synergy with other major facilities (VLT/VLTI, VISTA, VST, ALMA and SKA etc).

In March 2010, the ESO Council was provided with a preliminary report with the main conclusions from the E-ELT Site Selection Advisory Committee [1]. These conclusions confirmed that all the sites examined in the final shortlist (Armazones, Ventarrones, Tolonchar and Vizcachas in Chile, and La Palma in Spain) have very good conditions for astronomical observing, each one with its particular strengths. The technical report concluded that Cerro Armazones, near Paranal, stands out as the clearly preferred site, because it has the best balance of sky quality for all the factors considered and can be operated in an integrated fashion with ESO’s Paranal Observatory. Cerro Armazones and Paranal share the same ideal conditions for astronomical observations. In particular, over 320 nights are clear per year.

Taking into account the very clear recommendation of the Site Selection Advisory Committee and all other relevant aspects, especially the scientific quality of the site, Council has now endorsed the choice of Cerro Armazones as the E-ELT baseline site [2].

“Adding the transformational scientific capabilities of the E-ELT to the already tremendously powerful integrated VLT observatory guarantees the long-term future of Paranal as the most advanced optical/infrared observatory in the world and further strengthens ESO’s position as the world-leading organisation for ground-based astronomy,” says de Zeeuw.

In anticipation of the choice of Cerro Armazones as the future site of the E-ELT and to facilitate and support the project, the Chilean Government has agreed to donate to ESO a substantial tract of land contiguous to ESO’s Paranal property and containing Armazones in order to ensure the continued protection of the site against all adverse influences, in particular light pollution and mining activities.

Planck Casts New Light on Stellar Formation

A series of recent experiments has revealed that, more often than not, the halos of dark matter surrounding massive galaxy clusters are flattened and shaped like a cigar. Until now, astrophysicists believed that the mysterious stuff, which is believed to be five times more abundant than regular matter around the Universe, would clump up in rounded spheres. However, observations appear to paint a different picture, and experts are currently working on models that would help explain that.

The discovery could finally lead to studies that would result in the direct detection of the peculiar type of matter, whose existence can only be inferred from the gravitational pull it exerts on normal matter around it. “There are clear theoretical predictions that we expect dark mater halos to be flattened like this. It's a very beautiful, very clean and direct measurement of that,” explains expert Graham P. Smith, who is based at the University of Birmingham, in the United Kingdom. He is also a coauthor of the new study, which will appear in an upcoming issue of the esteemed scientific publication Monthly Notices of the Royal Astronomical Society.

In the new studies, the investigators looked at about 20 galaxy clusters, which are massive collections of galaxies, held together by strong gravitational interactions. In order to see the effect dark matter has on the largest organized structures in the Universe, the researchers used gravitational lensing. This observations technique analyzes how much light is bent when mass wraps time-space in order to determine the mass of celestial objects beyond. The Mauna Kea, Hawaii-based Subaru Telescope was used for the study, and the team took advantage of the Prime Focus Camera above all other instruments.

“What we're probing with these gravitational lensing observations is the dark matter distribution, because the dark matter dominates the mass on these large scales,” Smith says. The research team in charge of the study was led by National Astronomical Observatory of Japan expert Masamune Oguri and University of Tokyo scientist Masahiro Takada. The cigar-like shapes of these dark matter halos have been predicted in computer models of the cold dark matter theory, but thus far they have not been evidenced in practice in such a large number of galaxy clusters, Space reports.

“Precise measurements of the Cosmic Microwave Background are crucial to cosmology, and to understanding how our Universe formed and evolved. Attaining the highest-sensitivity (a few parts per million), highest-angular resolution (5 arcminutes) maps of the CMB – the goal of the Planck mission – requires the removal of the 'foreground' emission arising from the Milky Way. The information gleaned during this process is providing, as a by-product, a unique view of the processes that led to the formation of the stars in the galaxies that populate our Universe,” ESA officials write in a press release.

Planck maps the sky in nine frequencies using two state-of-the-art instruments, designed to produce high-sensitivity, multi-frequency measurements of the diffuse sky radiation: the High Frequency Instrument (HFI) includes the frequency bands 100 – 857 GHz, and the Low Frequency Instrument (LFI) includes the frequency bands 30-70 GHz. The first Planck all-sky survey began in August 2009 and is 98% complete (as of mid-March 2010).

Happy 20th Birthday Hubble

As the Hubble Space Telescope achieves the major milestone of two decades on orbit, NASA and the Space Telescope Science Institute, or STScI, in Baltimore are celebrating Hubble's journey of exploration with a stunning new picture and several online educational activities. There are also opportunities for people to explore galaxies as armchair scientists and send personal greetings to Hubble for posterity.

NASA is releasing a new Hubble photo of a small portion of one of the largest known star-birth regions in the galaxy, the Carina Nebula. Three light-year-tall towers of cool hydrogen laced with dust rise from the wall of the nebula. The scene is reminiscent of Hubble's classic "Pillars of Creation" photo from 1995, but even more striking.

To view the photo, visit: http://www.nasa.gov/hubble

NASA's best-recognized, longest-lived and most prolific space observatory was launched April 24, 1990, aboard the space shuttle Discovery during the STS-31 mission. Hubble discoveries revolutionized nearly all areas of current astronomical research from planetary science to cosmology.

Over the years, Hubble has suffered broken equipment, a bleary-eyed primary mirror, and the cancellation of a planned shuttle servicing mission. But the ingenuity and dedication of Hubble scientists, engineers and NASA astronauts allowed the observatory to rebound and thrive. The telescope's crisp vision continues to challenge scientists and the public with new discoveries and evocative images.

"Hubble is undoubtedly one of the most recognized and successful scientific projects in history," said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "Last year's space shuttle servicing mission left the observatory operating at peak capacity, giving it a new beginning for scientific achievements that impact our society."

Hubble fans worldwide are being invited to take an interactive journey with Hubble by visiting http://www.nasa.gov/externalflash/Hubble20/. They can also visit http://www.hubblesite.org to share the ways the telescope has affected them. Follow the "Messages to Hubble" link to send an e-mail, post a Facebook message, or send a cell phone text message. Fan messages will be stored in the Hubble data archive along with the telescope's science data. For those who use Twitter, you can follow @HubbleTelescope or post tweets using the Twitter hashtag #hst20.

The public also will have an opportunity to become at-home scientists by helping astronomers sort out the thousands of galaxies seen in a Hubble deep field observation. STScI is partnering with the Galaxy Zoo consortium of scientists to launch an Internet-based astronomy project where amateur astronomers can peruse and sort galaxies from Hubble's deepest view of the universe into their classic shapes: spiral, elliptical, and irregular. Dividing the galaxies into categories will allow astronomers to study how they relate to each other and provide clues that might help scientists understand how they formed.

To visit the Galaxy Zoo page, go to: http://hubble.galaxyzoo.org

For educators and students, STScI is creating an educational website called "Celebrating Hubble's 20th Anniversary." It offers links to facts and trivia about Hubble, a news story that chronicles the observatory's life and discoveries, and the IMAX "Hubble 3D" educator's guide. An anniversary poster containing Hubble's "hall-of-fame" images, including the Eagle Nebula and Saturn, also is being offered with downloadable classroom activity information.

Visit the website at: http://amazing-space.stsci.edu/hubble_20

To date, Hubble has observed more than 30,000 celestial targets and amassed more than a half-million pictures in its archive. The last astronaut servicing mission to Hubble in May 2009 made the telescope 100 times more powerful than when it was launched.

For Hubble 20th anniversary image files and more information, visit:

http://hubblesite.org/news/2010/13
http://heritage.stsci.edu/2010/13
http://www.spacetelescope.org/news/html/heic1007.html

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, D.C.

LUCIFER Allows Astronomers to Watch Stars Being Born

A new instrument for the world's largest optical telescope, the Large Binocular Telescope on Mount Graham, allows astronomers to observe the faintest and most distant objects in the universe.

Large Binocular Telescope (LBT) partners in the U.S, Germany and Italy announced April 21 that the first of two new innovative near-infrared cameras/spectrographs for the LBT is now available to astronomers for scientific observations at the telescope on Mount Graham in southeastern Arizona.

After more than a decade of design, manufacturing and testing, the new instrument - dubbed LUCIFER 1 - provides a powerful tool to gain spectacular insights into the universe - from the Milky Way to extremely distant galaxies. LUCIFER, built by a consortium of German institutes, will be followed by an identical twin instrument that will be delivered to the telescope in early 2011.

"With the large light-gathering power of the LBT, astronomers are now able to collect the spectral fingerprints of the faintest and most distant objects in the universe," said LBT director Richard Green, a professor of astronomy at the University of Arizona's Steward Observatory.

LUCIFER 1 and its twin are mounted at the focus points of the LBT's two giant 8.4-meter (27.6 foot) diameter telescope mirrors. Each instrument is cooled to -213 degrees Celsius in order to observe in the near-infrared wavelength range.

Near-infrared observations are essential for understanding the formation of stars and planets in our galaxy as well as revealing the secrets of the most distant and very young galaxies.

LUCIFER's innovative design allows astronomers to observe in unprecedented detail, for example star forming regions, which are commonly hidden by dust clouds.

The instrument is remarkably flexible, combining a large field of view with a high resolution. It provides three exchangeable cameras for imaging and spectroscopy in different resolutions according to observational requirements.

Astronomers use spectroscopy to analyze incoming light and answer questions such as how stars and galaxies formed and what they are made of.

Pulsars in many octaves

Simultaneous detection of pulses from pulsar PSR B1133+16 in four widely spaced bands, using the Effelsberg telescope at 3.5 cm wavelength, the Lovell telescope at 21 cm wavelength, and LOFAR high-band (HBAs) and low-band antennas (LBAs) at 170 cm and 430 cm wavelength, respectively. The shape of the pulsar's pulsed emission maps the spreading of magnetic field lines above the pulsar's magnetic poles.

A unique combination of telescopes allowed astronomers to simultaneously observe the radio wavelength light from six different pulsars across wavelengths from only 3.5 centimetres up to 7 metres - a difference-factor of 200, providing an unprecedented view of how radio pulsars shine. For this world record in wavelength coverage, the international team, including scientists from the Max Planck Institute for Radio Astronomy, used the new European LOFAR telescope, in combination with two of the world's largest radio telescopes, the 100 metre Effelsberg telescope in Germany and the 76 metre Lovell telescope in the United Kingdom. Pulsars are rapidly rotating neutron stars, which measure only about 20 kilometres across and yet are more massive than the Sun. They produce beams of radio light from their magnetic poles, which are observable over a wide range of wavelengths. For the last 40 years astronomers have been studying pulsars and have been getting closer to understanding the mechanism that generates these intense beams. They hypothesize that the emission seen at the different wavelengths emerges from different heights above the highly magnetized pulsar surface. Emission seen at a particular radio wavelength therefore provides a slice through the pulsar's surrounding "magnetosphere" (magnetized atmosphere).

Astronomers believe that pulsar emission at different radio wavelengths may be created at different heights above the star's magnetic poles. The magnetic field lines that accelerate particles spread apart as one moves further and further away from the pulsar's surface. Experimental support for this hypothesis is the observation that the pulses of some pulsars become stretched out at long wavelengths (Fig. 1). The shape of the pulsar's pulsed emission is seen to evolve quite drastically as a function of wavelength and maps the spreading of magnetic field lines above the pulsar's magnetic poles.

With any single telescope, a pulsar can only be observed in a relatively narrow range of wavelengths at any given time. By combining the traditional large Effelsberg and Lovell telescopes, observing at wavelengths of centimetres, with the next generation telescope LOFAR, observing at wavelengths of meters, the astronomers were able to observe a set of six pulsars, each simultaneously across a range of nearly 8 octaves. "For comparison, consider that we have simultaneously observed these pulsars over a range equivalent to all the tones spanned by a piano," says Jason Hessels of ASTRON Netherlands Institute for Radio Astronomy. "By simultaneously observing these pulsars at such a wide range of wavelengths, we can make many snapshots of what the pulsar's emission looks like at a range of heights above the star's magnetic poles," he adds.

Key to these observations was the use of the new LOFAR telescope, which has a collection of thousands of radio antennas in stations that are centred near Exloo, in the Netherlands, and that spread from there over distances of hundreds of kilometres into neighbouring countries, such as France, Germany, Sweden, and the United Kingdom. The data taken on all stations are brought together for data analysis via high-speed networks to a BlueGene/P supercomputer and powerful cluster computers at the University of Groningen Centre for Information Technology. LOFAR is operated as an integrated facility from the ASTRON headquarters in Dwingeloo, the Netherlands. The LOFAR telescope is currently being prepared for full-scale scientific observations, and the astronomers were excited to make such high-quality, pulsar measurements even in the testing phase.

Michael Kramer, director at the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, is excited about the enormous extension in wavelength coverage provided by LOFAR, of which the first international antenna station was built next to the Effelsberg telescope in Germany. "These observations show how LOFAR complements the existing radio telescopes in Europe, like the 100-m Effelsberg telescope, in an almost perfect way."

These observations have the primary goal of better understanding how pulsars pulse. However, there is also much to be learned beyond studying just the pulsar itself. "Not only do such observations give us a fantastic handle on understanding the emission of pulsars, they are also a powerful probe of the interstellar gas that is between us and the pulsar," says Ben Stappers of the University of Manchester.

"We are really excited to have the first international LOFAR station operating here in direct vicinity to the giant 100m Effelsberg radio telescope", says Kosmas Lazaridis from MPIfR. "The combination of both, large parabolic dishes for the centimetre regime, and new digital technology for the longer wavelengths provides a wealth of new data for our pulsar research programs."

The LOFAR telescope, spanning more than 1000 kilometres in Europe, will be completed in the next year and will be the most powerful telescope on Earth for observing the Universe at the longest possible radio wavelengths visible from the Earth's surface: 1-30 metres. It is expected that this will produce a flood of exciting new scientific results.

Source: Max-Planck-Gesellschaft

VISTA Captures Celestial Cat’s Hidden Secrets

The Cat’s Paw Nebula, NGC 6334, is a huge stellar nursery, the birthplace of hundreds of massive stars. In a magnificent new ESO image taken with the Visible and Infrared Survey Telescope for Astronomy (VISTA) at the Paranal Observatory in Chile, the glowing gas and dust clouds obscuring the view are penetrated by infrared light and some of the Cat’s hidden young stars are revealed.

Towards the heart of the Milky Way, 5500 light-years from Earth in the constellation of Scorpius (the Scorpion), the Cat’s Paw Nebula stretches across 50 light-years. In visible light, gas and dust are illuminated by hot young stars, creating strange reddish shapes that give the object its nickname. A recent image by ESO’s Wide Field Imager (WFI) at the La Silla Observatory (eso1003) captured this visible light view in great detail. NGC 6334 is one of the most active nurseries of massive stars in our galaxy.

VISTA, the latest addition to ESO’s Paranal Observatory in the Chilean Atacama Desert, is the world’s largest survey telescope (eso0949). It works at infrared wavelengths, seeing right through much of the dust that is such a beautiful but distracting aspect of the nebula, and revealing objects hidden from the sight of visible light telescopes. Visible light tends to be scattered and absorbed by interstellar dust, but the dust is nearly transparent to infrared light.

VISTA has a main mirror that is 4.1 metres across and it is equipped with the largest infrared camera on any telescope. It shares the spectacular viewing conditions with ESO’s Very Large Telescope (VLT), which is located on the nearby summit. With this powerful instrument at their command, astronomers were keen to see the birth pains of the big young stars in the Cat’s Paw Nebula, some nearly ten times the mass of the Sun. The view in the infrared is strikingly different from that in visible light. With the dust obscuring the view far less, they can learn much more about how these stars form and develop in their first few million years of life. VISTA’s very wide field of view allows the whole star-forming region to be imaged in one shot with much greater clarity than ever before.

The VISTA image is filled with countless stars of our Milky Way galaxy overlaid with spectacular tendrils of dark dust that are seen here fully for the first time. The dust is sufficiently thick in places to block even the near-infrared radiation to which VISTA’s camera is sensitive. In many of the dusty areas, such as those close to the centre of the picture, features that appear orange are apparent — evidence of otherwise hidden active young stars and their accompanying jets. Further out though, slightly older stars are laid bare to VISTA’s vision, revealing the processes taking them from their first nuclear fusion along the unsteady path of the first few million years of their lives.

The VISTA telescope is now embarking on several big surveys of the southern sky that will take years to complete. The telescope’s large mirror, high quality images, sensitive camera and huge field of view make it by far the most powerful infrared survey telescope on Earth. As this striking image shows, VISTA will keep astronomers busy analysing data they could not have otherwise acquired. This cat is out of the bag.

Source:- ESO

Making the invisible visible: New workhorse for the world’s largest optical telescope

A snapshot of a stellar nursery in our home galaxy, the Milky Way: a high-mass star forming region inside the giant molecular cloud S255, about 8,000 light-years away from Earth (1 light-year is roughly 10 trillion kilometers). Such clouds are typically opaque to visible light. However, infrared light can penetrate the dust, so that the LUCIFER image reveals the cluster of newly born stars and its complex environment in all their splendour. Image: Arjan Bik

The Large Binocular Telescope (LBT) partners in Germany, the U.S.A. and Italy are pleased to announce that the first of two new innovative near-infrared cameras/spectrographs for the LBT is now available to astronomers for scientific observations at the telescope on Mt. Graham in south-eastern Arizona. After more than a decade of design, manufacturing and testing, the new instrument, dubbed LUCIFER 1, provides a powerful tool to gain spectacular insights into the universe, from the Milky Way up to extremely distant galaxies. LUCIFER 1 has been built by a consortium of German institutes and will be followed by an identical twin instrument that will be delivered to the telescope in early 2011.

LUCIFER’s innovative design allows astronomers to observe in unprecedented detail, for example, star forming regions which are commonly hidden by dust clouds. The instrument provides unrivaled flexibility, with features such as a unique robotic arm that can replace spectroscopic masks within the instrument’s extreme sub-zero environment.

LUCIFER and its twin are mounted at the focus points of the LBT’s two giant 8.4-metre (27.6 foot) diameter telescope mirrors. Each instrument is cooled to a chilly -213 degrees Celsius in order to observe in the near-infrared (NIR) wavelength range. Near-infrared observations are essential for understanding the formation of stars and planets in our galaxy as well as revealing the secrets of the most distant and very young galaxies.

LUCIFER is a remarkable new multi-purpose instrument with great flexibility combining a large field of view with a high resolution. It provides three exchangeable cameras for imaging and spectroscopy in different resolutions according to observational requirements. Besides its outstanding imaging capability which presently makes use of 18 high-quality filters, LUCIFER allows the simultaneous spectroscopy of about two dozen objects in the infrared through laser-cut slit-masks. For highest flexibility the masks can be changed even at the cryogenic temperatures, through the innovative development of a unique robotic mask grabber which places the individual masks with absolute precision into the focal plane.

"Together with the large light gathering power of the LBT, astronomers are now able to collect the spectral fingerprints of the faintest and most distant objects in the universe." says Richard Green, the Director of the LBT. "After completion of the LBT adaptive secondary mirror system to correct for atmospheric perturbation, LUCIFER will show its full capability by delivering images with a quality that are otherwise only obtained from space-based observatories."

"Already the very first LUCIFER observations of star forming regions are giving us an indication of the enormous potential of the new instrument," said Thomas Henning, the chair of the German LBT-Partners.

The instruments have been built by a consortium of five German institutes led by the Center for Astronomy of Heidelberg University (Landessternwarte Heidelberg, LSW) together with the Max Planck Institute for Astronomy in Heidelberg (MPIA), the Max Planck Institute for Extraterrestrial Physics in Garching (MPE), the Astronomical Institute of the Ruhr-University in Bochum (AIRUB) as well as the University of Applied Sciences in Mannheim (Hochschule Mannheim).

Walter Seifert (LSW), Nancy Ageorges (MPE) and Marcus Jütte (AIRUB), responsible for the successful commissioning, spent more than half a year in several runs at the LBT site to make the telescope/instrument combination work efficiently. Holger Mandel, the Principal Investigator of LUCIFER said: "From the very beginning, there was uniform excitement about the promise of this instrument for cutting-edge science. Now, the amazing results speak for themselves."

Source:- Max Planck Society

NASA's Spitzer Space Telescope Discovers Extrasolar Planet Lacking Methane

PASADENA, Calif. - NASA's Spitzer Space Telescope has discovered something odd about a distant planet -- it lacks methane, an ingredient common to many of the planets in our solar system.

"It's a big puzzle," said Kevin Stevenson, a planetary sciences graduate student at the University of Central Florida in Orlando, lead author of a study appearing tomorrow, April 22 in the journal Nature. "Models tell us that the carbon in this planet should be in the form of methane. Theorists are going to be quite busy trying to figure this one out."

The discovery brings astronomers one step closer to probing the atmospheres of distant planets the size of Earth. The methane-free planet, called GJ 436b, is about the size of Neptune, making it the smallest distant planet that any telescope has successfully "tasted," or analyzed. Eventually, a larger space telescope could use the same kind of technique to search smaller, Earth-like worlds for methane and other chemical signs of life, such as water, oxygen and carbon dioxide.

"Ultimately, we want to find biosignatures on a small, rocky world. Oxygen, especially with even a little methane, would tell us that we humans might not be alone," said Stevenson.

"In this case, we expected to find methane not because of the presence of life, but because of the planet's chemistry. This type of planet should have cooked up methane. It's like dipping bread into beaten eggs, frying it, and getting oatmeal in the end," said Joseph Harrington of the University of Central Florida, the principal investigator of the research.

Methane is present on our life-bearing planet, manufactured primarily by microbes living in cows and soaking in waterlogged rice fields. All of the giant planets in our solar system have methane too, despite their lack of cows. Neptune is blue because of this chemical, which absorbs red light. Methane is a common ingredient of relatively cool bodies, including "failed" stars, which are called brown dwarfs.

In fact, any world with the common atmospheric mix of hydrogen, carbon and oxygen, and a temperature up to 1,000 Kelvin (1,340 degrees Fahrenheit) is expected to have a large amount of methane and a small amount of carbon monoxide. The carbon should "prefer" to be in the form of methane at these temperatures.

At 800 Kelvin (or 980 degrees Fahrenheit), GJ 436b is supposed to have abundant methane and little carbon monoxide. Spitzer observations have shown the opposite. The space telescope has captured the planet's light in six infrared wavelengths, showing evidence for carbon monoxide but not methane.

"We're scratching our heads," said Harrington. "But what this does tell us is that there is room for improvement in our models. Now we have actual data on faraway planets that will teach us what's really going on in their atmospheres."

GJ 436b is located 33 light-years away in the constellation Leo, the Lion. It rides in a tight, 2.64-day orbit around its small star, an "M-dwarf" much cooler than our sun. The planet transits, or crosses in front of, its star as viewed from Earth.

Spitzer was able to detect the faint glow of GJ 436b by watching it slip behind its star, an event called a secondary eclipse. As the planet disappears, the total light observed from the star system drops -- this drop is then measured to find the brightness of the planet at various wavelengths. The technique, first pioneered by Spitzer in 2005, has since been used to measure atmospheric components of several Jupiter-sized exoplanets, the so-called "hot Jupiters," and now the Neptune-sized GJ 436b.

"The Spitzer technique is being pushed to smaller, cooler planets more like our Earth than the previously studied hot Jupiters," said Charles Beichman, director of NASA's Exoplanet Science Institute at NASA's Jet Propulsion Laboratory and the California Institute of Technology, both in Pasadena, Calif. "In coming years, we can expect that a space telescope could characterize the atmosphere of a rocky planet a few times the size of the Earth. Such a planet might show signposts of life."

This research was performed before Spitzer ran out of its liquid coolant in May 2009, officially beginning its "warm" mission.

Other authors include: Sarah Nymeyer, William C. Bowman, Ryan A. Hardy and Nate B. Lust from the University of Central Florida; Nikku Madhusudhan and Sara Seager of the Massachusetts Institute of Technology, Cambridge; Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md.; and Emily Rauscher of Columbia University, New York.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer.

NRL Researchers Study Galaxy Mergers

The University of Hawaii 2.2-meter telescope.

Scientists at the Naval Research Laboratory have solved a long-standing dilemma about the mass of infrared bright merging galaxies. Because galaxies are the largest directly observable objects in the universe, learning more about their formation is key to understanding how the universe works.

Dr. Barry Rothberg and Dr. Jacqueline Fischer, both of the Infrared-Submillimeter Astrophysics & Techniques Section in the Remote Sensing Division, used new data from the 8-meter Gemini-South telescope in Chile along with earlier results from the W. M. Keck-2 10-meter and University of Hawaii 2.2-meter telescopes in Hawaii and archival data from the Hubble Space Telescope, to solve the problem. They have published a paper on their research findings on galaxy evolution in the Astrophysical Journal (March 20, 2010 Volume 712).

Galaxies in the Universe generally come in two shapes, spiral, like our own Milky Way, and elliptical, in which the stars move in random orbits, Rothberg explains. The largest galaxies in the Universe are elliptical in shape and how they formed is central to our understanding how the Universe has evolved over the last 15 billion years. The long-standing theory has been that spiral galaxies merge with each other forming most of the elliptical galaxies in the Universe. Spiral galaxies contain significant amounts of cold hydrogen gas. When they merge, the beautiful spiral patterns are destroyed and the gas is converted into new stars. The more gas present in the spiral galaxies, the more stars are formed and with it, large amounts of dust. The dust is heated by the young stars and radiates energy at infrared wavelengths.

Until recently scientists thought that these infrared bright merging galaxies were not massive enough to be the precursors of most elliptical galaxies in the Universe. The problem lay in the method of measuring their mass. The conventional method of measuring mass in dusty IR-bright galaxies uses near-infrared light to measure the random motions of old-stars. The larger the random motions, the more mass is present. Using near-infrared light makes it possible to penetrate the dust and see as many of the old stars as possible. However, a complication occurs when spiral galaxies merge, because most of their gas is funneled to the gravitational center of the system and forms a rotating disk. This rotating disk of gas is transformed into a rotating disk of young stars that is also very bright at near-infrared wavelengths. The rotating disk of young stars both outshines the old stars and makes it appear as if the old stars have significantly less random motion. In contrast to this conventional method, Rothberg and Fischer instead observed the random motions of old stars at shorter wavelengths effectively using the dust to their advantage to block the light from the young stars. Their new results showed that the old stars in merging galaxies have large random motions, which means they will eventually become very massive elliptical galaxies.

The next step for NRL researches is to directly observe the stellar disks in IR luminous mergers using three-dimensional spectroscopy. Each pixel is a spectrum, and from this the researchers can make two-dimensional maps of stellar motion and stellar age. This will allow them to measure the size, rotation, luminosity, mass and age of the central disk.

Source:- NRL

New Insight into How Neutron Stars Cool

Image comment: Image showing the Cassiopeia A supernova remnant. Inset depicts the neutron star at its core
Image credits: Image: NASA / CXC / Southampton / W. Ho et al. Illustration: NASA / CXC / M.Weiss

Using telescope data spanning an entire decade, researchers have recently compiled a new dataset on how the renowned supernova remnant Cassiopeia A's neutron star is evolving over time. The celestial body is the youngest known such formation to date, and so peering into the interior of this super-dense star is something that astronomers are very keen on doing. Details of the long-term study were presented Thursday, April 15, at the RAS National Astronomy Meeting, held in Glasgow, Scotland, PhysOrg reports.

The presentation was made by University of Southampton astronomer Dr Wynn Ho and colleague Dr Craig Heinke, who is based at the University of Alberta, in Canada. The team used images collected between 2000 and 2009, using the NASA Chandra X-Ray Observatory, one of the American space agency's four Great Observatories. “This is the first time that astronomers have been able to watch a young neutron star cool steadily over time. Chandra has given us a snapshot of the temperature roughly every two years for the past decade and we have seen the temperature drop during that time by about 3 [percent],” Dr Ho told colleagues gathered at the meeting.

Neutron stars are the collapsed cores of former massive stars that did not have sufficient mass or did not experience the necessary conditions to become a black hole. They are composed of considerable amounts of elementary particles called neutrons, which are compressed together by the force of gravity at unimaginably-high pressures. This means that the matter at their cores has a density that is trillions of times higher than that of lead. Generally, astrophysicists say that neutron stars are produced following supernova explosions. In the case of Cassiopeia A, the explosion is thought to have occurred around the year 1680.

Scientists believe that the remnant core was initially heated up to billions of degrees Celsius, but add that today it only has a temperature of around two million degrees. ”Young neutron stars cool through the emission of high-energy neutrinos – particles similar to photons but which do not interact much with normal matter and therefore are very difficult to detect. Since most of the neutrinos are produced deep inside the star, we can use the observed temperature changes to probe what’s going on in the neutron star’s core,” Ho added.

“ The structure of neutron stars determines how they cool, so this discovery will allow us to understand better what neutron stars are made of. Our observations of temperature variations already rule out some models for this cooling and has given us insights into the properties of matter that cannot be studied in laboratories on Earth,” he further explained. A paper detailing the study was submitted to the esteemed publication Astrophysical Journal.

M81's 'Halo' Sheds Light on Galaxy Formation

Visible light image of spiral galaxy M81 taken by Suprime-Cam.

Observations with Subaru Telescope's Prime Focus Camera (Suprime-Cam) have revealed an extended structure of the spiral galaxy Messier 81 (M81) that may hold a key to understanding the formation of galaxies. This structure could be M81's halo. Until now, ground-based telescopes have only observed individual stars in the haloes around the Milky Way and Andromeda Galaxies. Differences in M81's extended structure from the Milky Way's halo may point to variations in the formation histories of spiral galaxies.

M81 is one of the largest galaxies in the M81 Group, a group of 34 galaxies located toward the constellation Ursa Major. At 11.7 million light years from Earth, it is one of the closest groups to the Local group, the group of galaxies that includes our own Milky Way. Thanks to its proximity and similarity to the Milky Way, M81 provides an excellent laboratory for testing galaxy formation models.

The most prominent of these models predicts that galaxies are built up from the merging and accretion of many smaller galaxies that orbit within their gravitational sphere of influence. This chaotic, bottom-up growth leaves behind a halo of stars around massive spirals like the Milky Way. Do the findings about M81's extended structure, possibly its halo, support this view?

True to its promise as an effective tool for the study of galaxy evolution, Subaru's telescope has provided data to address this question. The enormous light-gathering power of Subaru Telescopes's 8.2 meter primary mirror and the wide field-of-view of its Suprime-Cam enabled the telescope to provide evidence for a faint, extended structural component beyond M81's bright optical disk. It probed into space over one-hundred times darker than the night sky and imperceptible to the naked eye. The telescope spotted individual stars and gathered enough of them to identify M81's extended component and analyze its physical properties.

The results defy exact classification of the extended structure as a halo. Although the spatial distribution of its stars resembles the Milky Way's halo, M81's "halo" differs from the Milky Way's in other respects. Measurements of the total light from all of its stars and analysis of their colors point to estimates that M81's "halo" could be several times brighter and contain more processed materials, nearly twice as much mass in the form of metals (all elements heavier than helium), than the Milky Way's halo.

These differences prompt some fascinating questions. Do we need to expand our definition of a halo? Does this structure have a very different formation history than the Milky Way's halo? Did these differences arise because M81 cannibalized more or different kinds of small galaxies in the past than the Milky Way did? Regardless of the answers to these queries, the results of this research contribute to the growing body of evidence that the outer structures of apparently similar galaxies are much more important and complex than astronomers have previously thought.

Provided by Subaru Telescope

Space Telescope Moves on with One Detector

Mission engineers and scientists with NASA's Galaxy Evolution Explorer, a space telescope that has been beaming back pictures of galaxies for three times its design lifespan, are no longer planning science observations around one of its two ultraviolet detectors.

"The remaining, near-ultraviolet detector is still busy probing galaxies both nearby and distant," said Kerry Erickson, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena. "We've got lots of science data coming down from space."

The Galaxy Evolution Explorer rocketed into space from a jet aircraft in 2003. For four years of its primary mission, it mapped tens of millions of galaxies across the sky in ultraviolet light, some as far back as 10 billion years in cosmic time. Its extended mission began in 2008, allowing it to probe deeper into more parts of the sky, and pluck out more galaxies.

Last May, the spacecraft's far-ultraviolet detector experienced an over-current condition, or essentially "shorted out," via a process called electron field emission. This detector sees higher-energy ultraviolet light, and thus hotter and younger stars within galaxies, than the telescope's other, near-ultraviolet detector. (The far-ultraviolet detector sees light with wavelengths between 135 and 180 nanometers, while the near-ultraviolet detector sees wavelengths between 180 and 280 nanometers.)

The far-ultraviolet detector has contributed significantly to the Galaxy Evolution Explorer's quest to understand how galaxies, including those like our own spiral Milky Way galaxy, blossom into maturity. It specializes in studies of star formation in nearby and distant galaxies. Perhaps the most significant discovery in this area is the identification of a transitional phase of galaxies, the teenagers of the galactic world. Astronomers long knew of young galaxies churning out stars, in addition to older, or dead, galaxies. But they did not know for certain whether the young ones mature into the older ones until the Galaxy Evolution Explorer found the missing links - the transitional galaxies (see http://www.jpl.nasa.gov/news/features.cfm?feature=1524).

In addition, one of the far-ultraviolet detector's most stunning finds is the humungous comet-like tail behind a speeding star called Mira. (See picture and article at http://www.jpl.nasa.gov/news/news.cfm?release=2007-090).

While the discovery of Mira's tail required the now-offline detector, almost all of the mission's targets could be seen by both detectors. Astronomers used the detectors' observations at different wavelengths to get an idea of a star or galaxy's temperature, age and mass. Much of this research can now be done by comparing near-ultraviolet data from the Galaxy Evolution Explorer with catalogued visible-light data from other telescopes. In addition, the wealth of far-ultraviolet observations to date will continue to be mined for decades to come.

The California Institute of Technology in Pasadena leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. JPL manages the mission and assembled the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission. Caltech manages JPL for NASA. ?

Graphics and additional information about the Galaxy Evolution Explorer are online at http://www.nasa.gov/galex and http://www.galex.caltech.edu.

Optical Interferometry Gains Popularity

Image comment: The European Southern Observatory's Very Large Telescope, in Chile, is also based on optical interferometry. It features four 8.2-meter aperture, and four 1.8-meter aperture instruments
Image credits: ESO

For more than 50 years, radio astronomy has benefited from the capabilities of a process called interferometry, in gaining some of the sharpest images of the Universe possible with existing technologies. But, in spite of their positive results, astronomers operating these observatories failed to inspire their colleagues working with instruments that looked at the Cosmos in visible light wavelengths. But, now, optical interferometry is beginning to make its way in new optical telescopes, and the results of observations are clearly improving, Nature News reports.

One clear example is the Center for High Angular Resolution Astronomy (CHARA) observatory, which features a Y-shaped array of six one-meter optical telescopes. Each individual component would stand no chance in front of other telescopes on its own, but together, they all act as a single 33-meter mirror. This ability is what allows astronomers at CHARA to boast of producing some of the sharpest images of the Universe ever taken on our planet. This is all possible due to the fact that the Mount Wilson, California-based instrument uses interferometry.

What this means is that the light captured by each of the six telescopes is not analyzed and processed independently. Rather, underground tunnels carry the signals to a central hub, where they are joined together in a single beam. This allows for the entire array to behave like a single, large mirror, which would be unfeasible to build in real-life. Additionally, interferometry carries the advantage of offering a slight 3D perspective as well, given that all individual components in the array snap their images from different vantage points. This is the basis that allows for the images to be combined seamlessly into a larger, more clear photograph.

By using interferometry, CHARA is able to boast a resolving power about 50 times better than that of the orbit-based Hubble Space Telescope. The ground-based observatory can image relatively small details on the surface of distant stars, for example, which are only apparent in images from other telescopes as diffuse blobs of light. “This is moving us into a realm that radio astronomy has been able to enjoy for decades,” University of Denver in Colorado astronomer Robert Stencel explains. He is the coauthor of a new study, detailing data that CHARA collected of a distant binary system that puzzled astronomers for about a decade.

WISE: Your Guide to the Infrared Sky

Learn about NASA's WISE mission and all the goodies it is expected to uncover in this new, interactive feature.

Click here to launch interactive

Fermi Maps An Active Galactic Smokestack Plumes

The gamma-ray output from Cen A's lobes exceeds their radio output by more than ten times. High-energy gamma rays detected by Fermi's Large Area Telescope are depicted as purple in this gamma ray/optical composite of the galaxy. Credit: NASA/DOE/Fermi LAT Collaboration, Capella Observatory

If our eyes could see radio waves, the nearby galaxy Centaurus A (Cen A) would be one of the biggest and brightest objects in the sky, nearly 20 times the apparent size of a full moon. What we can't see when looking at the galaxy in visible light is that it lies nestled between a pair of giant radio-emitting gas plumes ejected by its supersized black hole. Each plume is nearly a million light-years long.

NASA's Fermi Gamma-Ray Space Telescope maps gamma rays, radiation that typically packs 100 billion times the energy of radio waves. Nevertheless, and to the surprise of many astrophysicists, Cen A's plumes show up clearly in the satellite's first 10 months of data. The study appears in Thursday's edition of Science Express.

"This is something we've never seen before in gamma rays," said Teddy Cheung, a Fermi team member at the Naval Research Laboratory in Washington. "Not only do we see the extended radio lobes, but their gamma-ray output is more than ten times greater than their radio output." If gamma-ray telescopes had matured before their radio counterparts, astronomers would have instead classified Cen A as a "gamma-ray galaxy."

Also known as NGC 5128, Cen A is located about 12 million light-years away in the constellation Centaurus and is one of the first celestial radio sources identified with a galaxy.

"A hallmark of radio galaxies is the presence of huge, double-lobed radio-emitting structures around otherwise normal-looking elliptical galaxies," said Jurgen Knodlseder, a Fermi collaborator at the Center for the Study of Space Radiation in Toulouse, France. "Cen A is a textbook example."

Astronomers classify Cen A as an "active galaxy," a term applied to any galaxy whose central region exhibits strong emissions at many different wavelengths. "What powers these emissions is a well-fed black hole millions of times more massive than our sun," said Yasushi Fukazawa, a co-author of the study at Hiroshima University in Japan. "The black hole somehow diverts some of the matter falling toward it into two oppositely directed jets that stream away from the center."

Fueled by a black hole estimated at hundreds of millions of times the sun's mass, Cen A ejects magnetized particle jets moving near the speed of light. Over the course of tens of millions of years, these jets puffed out two giant bubbles filled with magnetic fields and energetic particles - the radio lobes we now see. The radio waves arise as high-speed electrons spiral through the lobes' tangled magnetic fields.

But where do gamma rays - the highest-energy form of light - come from?

The entire universe is filled with low-energy radiation - radio photons from the all-pervasive cosmic microwave background, as well as infrared and visible light from stars and galaxies. The presence of this radiation is the key to understanding Cen A's gamma rays.

"When one of these photons collides with a super-fast particle in the radio lobes, the photon receives such an energy boost, it becomes a gamma ray," explained co-author Lukasz Stawarz at the Japan Aerospace Exploration Agency in Sagamihara, Japan.

Although it sounds more like billiards than astrophysics, this process, called inverse Compton scattering, is a common way of making cosmic gamma rays. For Cen A, an especially important aspect is the case where photons from the cosmic microwave background ricochet off of the highest-energy particles in the radio lobes.

In dozens of active galaxies, this process has been shown to produce X-rays. But the Cen A study marks the first case where astronomers have solid evidence that microwave photons can be kicked up to gamma-ray energies.

Fermi cataloged hundreds of blazars and other types of active galaxies in its first year. Before its mission ends, that number may reach several thousand. But because Cen A is so close, so large and so vigorous, it may be the only active galaxy Fermi will view this way.

With Centaurus A, Fermi hit the jackpot.

Astronomers See Historical Supernova From a New Angle

Chandra X-ray Observatory image of the supernova remnant Cassiopeia A (Cas A). The red, green, and blue regions in this X-ray image of Cas A show where the intensity of low, medium, and high-energy X-rays, respectively, is greatest. While this photo shows the remains of the exploded star, light echoes show us reflected light from the explosion itself.

Credit: NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.

Since Galileo first pointed a telescope at the sky 400 years ago, a myriad of technological advances have allowed astronomers to look at very faint objects, very distant objects, and even light that's invisible to the human eye. Yet, one aspect usually remains out of reach - the benefit of a 3-D perspective.

Our telescopes show the Milky Way galaxy only as it appears from one vantage point: our solar system. Now, using a simple but powerful technique, a group of astronomers led by Armin Rest of Harvard University has seen an exploding star or supernova from several angles.

"The same event looks different from different places in the Milky Way," said Rest. "For the first time, we can see a supernova from an alien perspective."

The supernova left behind the gaseous remnant Cassiopeia A. The supernova's light washed over the Earth about 330 years ago. But light that took a longer path, reflecting off clouds of interstellar dust, is just now reaching us. This faint, reflected light is what the astronomers have detected.

The technique is based on the familiar concept of an echo, but applied to light instead of sound. If you yell, "Echo!" in a cave, sound waves bounce off the walls and reflect back to your ears, creating echoes. Similarly, light from the supernova reflects off interstellar dust to the Earth. The dust cloud acts like a mirror, creating light echoes that come from different directions depending on where the clouds are located.

"Just like mirrors in a changing room show you a clothing outfit from all sides, interstellar dust clouds act like mirrors to show us different sides of the supernova," explained Rest.

Moreover, an audible echo is delayed since it takes time for the sound waves to bounce around the cave and back. Light echoes also are delayed by the time it takes for light to travel to the dust and reflect back. As a result, light echoing from the supernova can reach us hundreds of years after the supernova itself has faded away.

Not only do light echoes give astronomers a chance to directly study historical supernovae, they also provide a 3-D perspective since each echo comes from a spot with a different view of the explosion.

Most people think a supernova is like a powerful fireworks blast, expanding outward in a round shell that looks the same from every angle. But by studying the light echoes, the team discovered that one direction in particular looked significantly different than the others.

They found signs of gas from the stellar explosion streaming toward one point at a speed almost 9 million miles per hour (2,500 miles per second) faster than any other observed direction.

"This supernova was two-faced!" said Smithsonian co-author and Clay Fellow Ryan Foley. "In one direction the exploding star was blasted to a much higher speed."

Previous studies support the team's finding. For example, the neutron star created when the star's core collapsed is zooming through space at nearly 800,000 miles per hour in a direction opposite the unique light echo. The explosion may have kicked gas one way and the neutron star out the other side (a consequence of Newton's third law of motion, which states that every action has an equal and opposite reaction).

By combining the new light-echo measurements and the movement of the neutron star with X-ray data on the supernova remnant, astronomers have assembled a 3-D perspective, giving them new insight into the Cas A supernova.

"Now we can connect the dots from the explosion itself, to the supernova's light, to the supernova remnant," said Foley.

Cassiopeia A is located about 16,000 light-years from Earth and contains matter at temperatures of around 50 million degrees F, causing it to glow in X-rays. A 3-D computer model of the remnant is online.

The Mayall 4-meter telescope at Kitt Peak National Observatory was used to locate the light echoes. Follow-up spectra were obtained with the 10-meter Keck I Telescope.

The journal paper describing this discovery is available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Ashes To Ashes Dust To Dust Chandra And Spitzer Have The Gos

A composite image from NASA's Chandra (blue) and Spitzer (green and red-yellow) space telescopes shows the dusty remains of a collapsed star, a supernova remnant called G54.1+0.3. The white source at the center is a dead star called a pulsar, generating a wind of high-energy particles seen by Chandra in blue. The wind expands into the surrounding environment. The infrared shell that surrounds the pulsar wind, seen in red, is made up of gas and dust that condensed out of debris from the supernova explosion. A nearby cluster of stars is being engulfed by the dust. The nature and quantity of dust produced in supernova explosions is a long-standing mystery, and G54.1+0.3 supplies an important piece to the puzzle. Image credit: NASA/CXC/JPL-Caltech/Harvard-Smithsonian CfA

A new image from NASA's Chandra and Spitzer space telescopes shows the dusty remains of a collapsed star. The dust is flying past and engulfing a nearby family of stars.

"Scientists think the stars in the image are part of a stellar cluster in which a supernova exploded," said Tea Temin of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., who led the study. "The material ejected in the explosion is now blowing past these stars at high velocities."

The composite image of G54.1+0.3 shows the Chandra X-ray Observatory data in blue, and data from the Spitzer Space Telescope in green (shorter wavelength) and red-yellow (longer).

The white source near the center of the image is a dense, rapidly rotating neutron star, or pulsar, left behind after a core-collapse supernova explosion. The pulsar generates a wind of high-energy particles - seen in the Chandra data - that expands into the surrounding environment, illuminating the material ejected in the supernova explosion.

The infrared shell that surrounds the pulsar wind is made up of gas and dust that condensed out of debris from the supernova. As the cold dust expands into the surroundings, it is heated and lit up by the stars in the cluster so that it is observable in infrared.

The dust closest to the stars is the hottest and is seen glowing in yellow in the image. Some of the dust is also being heated by the expanding pulsar wind as it overtakes the material in the shell.

The unique environment into which this supernova exploded makes it possible for astronomers to observe the condensed dust from the supernova that is usually too cold to emit in infrared. Without the presence of the stellar cluster, it would not be possible to observe this dust until it becomes energized and heated by a shock wave from the supernova.

However, the very action of such shock heating would destroy many of the smaller dust particles. In G54.1+0.3, astronomers are observing pristine dust before any such destruction.

G54.1+0.3 provides an exciting opportunity for astronomers to study the freshly formed supernova dust before it becomes altered and destroyed by shocks. The nature and quantity of dust produced in supernova explosions is a long-standing mystery, and G54.1+0.3 supplies an important piece to the puzzle.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

The Spitzer observations were made before the telescope ran out of its coolant in May 2009 and began its "warm" mission. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages Spitzer for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.