jeudi 10 janvier 2013

NASA Rules Out Earth Impact in 2036 for Asteroid Apophis

Asteroid Watch.

Jan. 10, 2013

NASA scientists at the agency's Jet Propulsion Laboratory in Pasadena, Calif., effectively have ruled out the possibility the asteroid Apophis will impact Earth during a close flyby in 2036. The scientists used updated information obtained by NASA-supported telescopes in 2011 and 2012, as well as new data from the time leading up to Apophis' distant Earth flyby yesterday (Jan. 9).

Discovered in 2004, the asteroid, which is the size of three-and-a-half football fields, gathered the immediate attention of space scientists and the media when initial calculations of its orbit indicated a 2.7 percent possibility of an Earth impact during a close flyby in 2029. Data discovered during a search of old astronomical images provided the additional information required to rule out the 2029 impact scenario, but a remote possibility of one in 2036 remained - until yesterday.

"With the new data provided by the Magdalena Ridge [New Mexico Institute of Mining and Technology] and the Pan-STARRS [Univ. of Hawaii] optical observatories, along with very recent data provided by the Goldstone Solar System Radar, we have effectively ruled out the possibility of an Earth impact by Apophis in 2036," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at JPL. "The impact odds as they stand now are less than one in a million, which makes us comfortable saying we can effectively rule out an Earth impact in 2036. Our interest in asteroid Apophis will essentially be for its scientific interest for the foreseeable future."

Asteroid Apophis was discovered on June 19, 2004. Image credit: UH/IA

The April 13, 2029, flyby of asteroid Apophis will be one for the record books. On that date, Apophis will become the closest flyby of an asteroid of its size when it comes no closer than 19, 400 miles (31,300 kilometers) above Earth's surface.

"But much sooner, a closer approach by a lesser-known asteroid is going to occur in the middle of next month when a 40-meter-sized asteroid, 2012 DA14, flies safely past Earth's surface at about 17,200 miles," said Yeomans. "With new telescopes coming online, the upgrade of existing telescopes and the continued refinement of our orbital determination process, there's never a dull moment working on near-Earth objects."

NASA detects and tracks asteroids and comets passing close to Earth using both ground and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them and plots their orbits to determine if any could be potentially hazardous to our planet.

The Near-Earth Object Program Office at JPL manages the technical and scientific activities for NASA's Near-Earth Object Program of the Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

For more information about asteroids and near-Earth objects, visit: Updates about near-Earth objects are also available by following AsteroidWatch on Twitter at .

Image, Text, Credits: NASA / Dwayne Brown / JPL / DC Agle.


NASA's GALEX Reveals the Largest-Known Spiral Galaxy

NASA GALEX Mission patch.

Jan. 10, 2013

This composite of the giant barred spiral galaxy NGC 6872 combines visible light images from the European Southern Observatory's Very Large Telescope with far-ultraviolet (1,528 angstroms) data from NASA's GALEX and 3.6-micron infrared data acquired by NASA's Spitzer Space Telescope. A previously unsuspected tidal dwarf galaxy candidate (circled) appears only in the ultraviolet, indicating the presence of many hot young stars. IC 4970, the small disk galaxy interacting with NGC 6872, is located above the spiral's central region. The spiral is 522,000 light-years across from the tip of one outstretched arm to the tip of the other, which makes it about 5 times the size of our home galaxy, the Milky Way. Images of lower resolution from the Digital Sky Survey were used to fill in marginal areas not covered by the other data. Credit: NASA's Goddard Space Flight Center/ESO/JPL-Caltech/DSS.

The spectacular barred spiral galaxy NGC 6872 has ranked among the biggest stellar systems for decades. Now a team of astronomers from the United States, Chile and Brazil has crowned it the largest-known spiral, based on archival data from NASA's Galaxy Evolution Explorer (GALEX) mission, which has since been loaned to the California Institute of Technology, Pasadena, Calif.

Measuring tip-to-tip across its two outsized spiral arms, NGC 6872 spans more than 522,000 light-years, making it more than five times the size of our Milky Way galaxy.

"Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system," said lead scientist Rafael Eufrasio, a research assistant at NASA's Goddard Space Flight Center in Greenbelt, Md., and a doctoral student at Catholic University of America in Washington. He presented the findings Thursday at the American Astronomical Society meeting in Long Beach, Calif.

The galaxy's unusual size and appearance stem from its interaction with a much smaller disk galaxy named IC 4970, which has only about one-fifth the mass of NGC 6872. The odd couple is located 212 million light-years from Earth in the southern constellation Pavo.

Astronomers think large galaxies, including our own, grew through mergers and acquisitions -- assembling over billions of years by absorbing numerous smaller systems.

Intriguingly, the gravitational interaction of NGC 6872 and IC 4970 may have done the opposite, spawning what may develop into a new small galaxy.

"The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems," said team member Duilia de Mello, a professor of astronomy at Catholic University.

Computer simulations of the collision between NGC 6872 and IC 4970 reproduce the basic features of the galaxies as we see them today. They indicate that IC 4970's closest encounter occurred 130 million years ago and that the smaller galaxy followed a path (dashed curve) close to the plane of the spiral's disk and in the same direction it rotates. Credit: NASA's Goddard Space Flight Center, after C. Horellou (Onsala Space Observatory) and B. Koribalski (ATNF).

The tidal dwarf candidate is brighter in the ultraviolet than other regions of the galaxy, a sign it bears a rich supply of hot young stars less than 200 million years old.

The researchers studied the galaxy across the spectrum using archival data from the European Southern Observatory's Very Large Telescope, the Two Micron All Sky Survey, and NASA's Spitzer Space Telescope, as well as GALEX.

By analyzing the distribution of energy by wavelength, the team uncovered a distinct pattern of stellar age along the galaxy's two prominent spiral arms. The youngest stars appear in the far end of the northwestern arm, within the tidal dwarf candidate, and stellar ages skew progressively older toward the galaxy's center.

The southwestern arm displays the same pattern, which is likely connected to waves of star formation triggered by the galactic encounter.

A 2007 study by Cathy Horellou at Onsala Space Observatory in Sweden and Baerbel Koribalski of the Australia National Telescope Facility developed computer simulations of the collision that reproduced the overall appearance of the system as we see it today. According to the closest match, IC 4970 made its closest approach about 130 million years ago and followed a path that took it nearly along the plane of the spiral's disk in the same direction it rotates. The current study is consistent with this picture.

As in all barred spirals, NGC 6872 contains a stellar bar component that transitions between the spiral arms and the galaxy's central regions. Measuring about 26,000 light-years in radius, or about twice the average length found in nearby barred spirals, it is a bar that befits a giant galaxy.

GALEX spacecraft. Image Credit: NASA's Goddard Space Flight Center / JPL

The team found no sign of recent star formation along the bar, which indicates it formed at least a few billion years ago. Its aged stars provide a fossil record of the galaxy's stellar population before the encounter with IC 4970 stirred things up.

"Understanding the structure and dynamics of nearby interacting systems like this one brings us a step closer to placing these events into their proper cosmological context, paving the way to decoding what we find in younger, more distant systems," said team member and Goddard astrophysicist Eli Dwek.

The study also included Fernanda Urrutia-Viscarra and Claudia Mendes de Oliveira at the University of Sao Paulo in Brazil and Dimitri Gadotti at the European Southern Observatory in Santiago, Chile.

The GALEX mission is led by the California Institute of Technology in Pasadena, which is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. GALEX was developed under NASA's Explorers Program managed by NASA's Goddard Space Flight Center. In May 2012, NASA loaned GALEX to Caltech, which continues spacecraft operations and data management using private funds.

Related Links:

Paper: "Stars and Gas in the Very Large Interacting Galaxy NGC 6872." doi: 10.1051/0004-6361:20066023:

"IC 4970 and NGC 6872: Galaxy Collision Switches on Black Hole" (12.10.2009):

Image (mentioned), Text, Credits: NASA /  Goddard Space Flight Center / Francis Reddy.


A Jumble of Exotic Stars

ESO - European Southern Observatory logo.

10 January 2013

New VISTA snap of star cluster 47 Tucanae

 The globular star cluster 47 Tucanae

This new infrared image from ESO’s VISTA telescope shows the globular cluster 47 Tucanae in striking detail. This cluster contains millions of stars, and there are many nestled at its core that are exotic and display unusual properties. Studying objects within clusters like 47 Tucanae may help us to understand how these oddballs form and interact. This image is very sharp and deep due to the size, sensitivity, and location of VISTA, which is sited at ESO's Paranal Observatory in Chile.

The globular star cluster 47 Tucanae in the constellation of Tucana (The Toucan)

Globular clusters are vast, spherical clouds of old stars bound together by gravity. They are found circling the cores of galaxies, as satellites orbit the Earth. These star clumps contain very little dust and gas — it is thought that most of it has been either blown from the cluster by winds and explosions from the stars within, or stripped away by interstellar gas interacting with the cluster. Any remaining material coalesced to form stars billions of years ago.

These globular clusters spark a considerable amount of interest for astronomers — 47 Tucanae, otherwise known as NGC 104, is a huge, ancient globular cluster about 15 000 light-years away from us, and is known to contain many bizarre and interesting stars and systems.

Wide-field view of the sky around the globular cluster 47 Tucanae

Located in the southern constellation of Tucana (The Toucan), 47 Tucanae orbits our Milky Way. At about 120 light-years across it is so large that, despite its distance, it looks about as big as the full Moon. Hosting millions of stars, it is one of the brightest and most massive globular clusters known and is visible to the naked eye [1]. In amongst the swirling mass of stars at its heart lie many intriguing systems, including X-ray sources, variable stars, vampire stars, unexpectedly bright “normal” stars known as blue stragglers (eso1243), and tiny objects known as millisecond pulsars, small dead stars that rotate astonishingly quickly [2].

Red giants, stars that have exhausted the fuel in their cores and swollen in size, are scattered across this VISTA image and are easy to pick out, glowing a deep amber against the bright white-yellow background stars. The densely packed core is contrasted against the more sparse outer regions of the cluster, and in the background huge numbers of stars in the Small Magellanic Cloud are visible.

A close look at the globular star cluster 47 Tucanae

This image was taken using ESO’s VISTA (Visible and Infrared Survey Telescope for Astronomy) as part of a survey of the region of the Magellanic Clouds, two of the closest known galaxies to us. 47 Tucanae, although much closer than the Clouds, by chance lies in the the foreground of the Small Magellanic Cloud (eso1008), and was snapped during the survey.

VISTA is the world’s largest telescope dedicated to mapping the sky. Located at ESO’s Paranal Observatory in Chile, this infrared telescope, with its large mirror, wide field of view and sensitive detectors, is revealing a new view of the southern sky. Using a combination of sharp infrared images — such as the VISTA image above — and visible-light observations allows astronomers to probe the contents and history of objects like 47 Tucanae in great detail.


[1] There are over 150 globular clusters orbiting our galaxy. 47 Tucanae is the second most massive after Omega Centauri (eso0844).

[2] Millisecond pulsars are incredibly quickly rotating versions of regular pulsars, highly magnetised, rotating stellar remnants that emit bursts of radiation as they spin. There are 23 known millisecond pulsars in 47 Tucanae — more than in all other globular clusters bar one, Terzan 5 (eso0945).
More information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.


Photos of VISTA:

Pictures of Paranal Observatory:

Other images taken with VISTA:

Images, Text, Credits: ESO / M.-R. Cioni / VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit / IAU, and Sky & Telescope / Digitized Sky Survey 2, Acknowledgment: Davide De Martin / Video: ESO/Digitized Sky Survey 2/M.-R. Cioni/VISTA Magellanic Cloud Survey/Stanislav Volskiy, acknowledgment: Cambridge Astronomical Survey Unit / Music: movetwo.


mercredi 9 janvier 2013

Robot Spheres in Zero-Gravity Action

NASA - Spheres Mission patch.

Jan. 9, 2013

 André and Spheres robots

A squadron of mini satellites on the International Space Station will wake up this Friday to obey remote commands from students across Europe. Watch a live broadcast from space as teams make the droids compete in a space game called RetroSpheres.

Up until now the students have run their code in a virtual world, but this Friday the high-school finals will be held using the real thing: robotic droids on the International Space Station. This year’s RetroSpheres scenario involves using the Spheres, which move using jets of compressed gas, to push simulated space debris out of orbit.
Six alliances made of European finalists from Italy, Germany, Spain and Portugal will confront each other and see their computer code operate robots in space for the first time.

2012 Spheres finals on International Space Station

ESA astronaut André Kuipers will provide commentary from ESA’s space research and technology centre, ESTEC, in the Netherlands, as NASA’s Kevin Ford and Tom Marshburn set up the games on the Station. Over 130 students will be at ESTEC with André to learn more about robotics and run their code on the Spheres floating in the Space Station.

You can follow the event this Friday from 14:30 to 17:30 CET via ESA web-tv:

For more information about the International Space Station, visit:

Images, Text, Credits: NASA / ESA.


Herschel Intercepts Asteroid Apophis

ESA - Herschel Space Telescope patch.

Jan. 09, 2013

 Herschel’s three-colour view of asteroid Apophis

ESA’s Herschel space observatory made new observations of asteroid Apophis as it approached Earth this weekend. The data shows the asteroid to be bigger than first estimated, and less reflective.

Catalogued as asteroid (99942) Apophis (previously 2004 MN4), it is often nicknamed ‘the doomsday asteroid’ in popular media, after initial observations made after its discovery in 2004 gave it a 2.7% chance of striking Earth in April 2029.

With additional data, however, an impact in 2029 was soon ruled out, although the asteroid will pass within 36 000 km of Earth’s surface, closer even than the orbits of geostationary satellites.

The asteroid will return to Earth’s neighbourhood again in 2036, but quite how close it will come then is uncertain, as the 2029 approach is predicted to alter its orbit substantially. Obtaining improved physical parameters for Apophis and its orbit is thus of great importance in being able to make better predictions of its future trajectory.

Herschel had a good opportunity at the weekend, observing the asteroid for about two hours on its approach to Earth, ahead of today’s closest encounter at a little less than one tenth of the distance from Earth to the Sun: about 14.5 million km. The observations were made as part of Herschel’s Guaranteed Time Programme MACH‑11.

“As well as the data being scientifically important in their own right, understanding key properties of asteroids will provide vital details for missions that might eventually visit potentially hazardous objects,” says Laurence O'Rourke, Principal Investigator of the MACH-11 observing programme, from the European Space Astronomy Centre (ESAC), near Madrid, Spain.

“Apophis is only the second near-Earth asteroid observed by Herschel, and these were the fastest tracked observations by the space telescope – the asteroid moved at a rate of 205 arcseconds per hour as seen from Herschel’s viewpoint.”

Apophis temperature model

Herschel provided the first thermal infrared observations of Apophis at different wavelengths, which together with optical measurements helped refine estimates of the asteroid’s properties. Previous estimates bracketed the asteroid’s average diameter at 270 ± 60 m; the new Herschel observations returned a more precise diameter of 325 ± 15 m.

“The 20% increase in diameter, from 270 to 325 m, translates into a 75% increase in our estimates of the asteroid’s volume or mass,” says Thomas Müller of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, who is leading the analysis of the new data.

By analysing the heat emitted by Apophis, Herschel also provided a new estimate of the asteroid’s albedo – a measure of its reflectivity – of 0.23. This value means that 23% of the sunlight falling onto the asteroid is reflected; the rest is absorbed and heats up the asteroid. The previous albedo estimate for Apophis was 0.33.

Knowing the thermal properties of an asteroid indicates how its orbit might be altered due to subtle heating by the Sun. Known as the Yarkovsky effect, the heating and cooling cycle of a small body as it rotates and as its distance from the Sun changes can instigate long-term changes to the asteroid’s orbit.

Herschel Space Telescope

“These numbers are first estimates based on the Herschel measurements alone, and other ongoing ground-based campaigns might produce additional pieces of information which will allow us to improve our results,” adds Müller.

“Although Apophis initially caught public interest as a possible Earth impactor, which is now considered highly improbable for the foreseeable future, it is of considerable interest in its own right, and as an example of the class of Near Earth Objects,” says Göran Pilbratt, ESA’s Herschel Project Scientist.

“Our unique Herschel measurements play a key role for the physical characterisation of Apophis, and will improve the long-term prediction of its orbit.”

Related links:

Herschel observations of YU55:

Herschel overview:

Online Showcase of Herschel images:

Space Situational Awareness:


Images, Text, Credits: ESA / Herschel / PACS / MACH-11/MPE/B.Altieri (ESAC) and C. Kiss (Konkoly Observatory) / T.Müller MPE (Germany).


mardi 8 janvier 2013

NASA's & ESA's Hubble Reveals Rogue Planetary Orbit For Fomalhaut B

NASA / ESA - Hubble Space Telescope patch.

Jan. 9, 2013

This false-color composite image, taken with the Hubble Space Telescope, reveals the orbital motion of the planet Fomalhaut b. Based on these observations, astronomers calculated that the planet is in a 2,000-year-long, highly elliptical orbit. The planet will appear to cross a vast belt of debris around the star roughly 20 years from now. If the planet's orbit lies in the same plane with the belt, icy and rocky debris in the belt could crash into the planet's atmosphere and produce various phenomena. The black circle at the center of the image blocks out the light from the bright star, allowing reflected light from the belt and planet to be photographed. The Hubble images were taken with the Space Telescope Imaging Spectrograph in 2010 and 2012. Credit: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute)

Newly released NASA Hubble Space Telescope images of a vast debris disk encircling the nearby star Fomalhaut and a mysterious planet circling it may provide forensic evidence of a titanic planetary disruption in the system.

Astronomers are surprised to find the debris belt is wider than previously known, spanning a section of space from 14 to nearly 20 billion miles from the star. Even more surprisingly, the latest Hubble images have allowed a team of astronomers to calculate the planet follows an unusual elliptical orbit that carries it on a potentially destructive path through the vast dust ring.

The planet, called Fomalhaut b, swings as close to its star as 4.6 billion miles, and the outermost point of its orbit is 27 billion miles away from the star. The orbit was recalculated from the newest Hubble observation made last year.

"We are shocked. This is not what we expected," said Paul Kalas of the University of California at Berkeley and the SETI Institute in Mountain View, Calif.

The Fomalhaut team led by Kalas considers this circumstantial evidence there may be other planet-like bodies in the system that gravitationally disturbed Fomalhaut b to place it in such a highly eccentric orbit. The team presented its finding Tuesday at the 221st meeting of the American Astronomical Society in Long Beach, Calif.

Among several scenarios to explain Fomalhaut b's 2,000-year-long orbit is the hypothesis that an as yet undiscovered planet gravitationally ejected Fomalhaut b from a position closer to the star, and sent it flying in an orbit that extends beyond the dust belt.

"Hot Jupiters get tossed through scattering events, where one planet goes in and one gets thrown out," said co-investigator Mark Clampin of NASA's Goddard Space Flight Center in Greenbelt, Md. "This could be the planet that gets thrown out."

Image above: Jupiter get tossed through scattering events, Galileo images of the comet Shoemaker Levy impact on Jupiter in in July 1994. Image credit: NASA.

Hubble also found the dust and ice belt encircling the star Fomalhaut has an apparent gap slicing across the belt. This might have been carved by another undetected planet. Hubble's exquisite view of the dust belt shows irregularities that strongly motivate a search for other planets in the system.

If its orbit lies in the same plane with the dust belt, then Fomalhaut b will intersect the belt around 2032 on the outbound leg of its orbit. During the crossing, icy and rocky debris in the belt could crash into the planet's atmosphere and create the type of cosmic fireworks seen when Comet Shoemaker-Levy 9 crashed into Jupiter. Most of the fireworks from collisions will be seen in infrared light. However, if Fomalhaut b is not co-planar with the belt, the only thing to be seen will be a gradual dimming of Fomalhaut b as it travels farther from the star.

Kalas hypothesized that Fomalhaut b's extreme orbit is a major clue in explaining why the planet is unusually bright in visible light, but very dim in infrared light. It is possible the planet's optical brightness originates from a ring or shroud of dust around the planet, which reflects starlight. The dust would be rapidly produced by satellites orbiting the planet, which would suffer extreme erosion by impacts and gravitational stirring when Fomalhaut b enters into the planetary system after a millennium of deep freeze beyond the main belt. An analogy can be found by looking at Saturn, which has a tenuous, but very large dust ring produced when meteoroids hit the outer moon Phoebe.

The team has also considered a different scenario where a hypothetical second dwarf planet suffered a catastrophic collision with Fomalhaut b. The collision scenario would explain why the star Fomalhaut has a narrow outer belt linked to an extreme planet. But in this case the belt is young, less than 10,000 years old, and it is difficult to produce energetic collisions far from the star in such young systems.

Fomalhaut is a special system because it looks like scientists may have a snapshot of what our solar system was doing 4 billion years ago. The planetary architecture is being redrawn, the comet belts are evolving, and planets may be gaining and losing their moons. Astronomers will continue monitoring Fomalhaut b for decades to come because they may have a chance to observe a planet entering an icy debris belt that is like the Kuiper Belt at the fringe of our own solar system.

For more information and for related images, please visit:

Images (mentioned), Text, Credits: NASA / J.D. Harrington / ESA / Space Telescope Science Institute / Ray Villard.

Best regards,

NASA Telescopes See Weather Patterns in Brown Dwarf

NASA / ESA - Hubble Space Telescope patch / NASA - Spitzer Space Telescope patch.

Jan. 9, 2013

This artist's conception illustrates the brown dwarf named 2MASSJ22282889-431026. Image credit: NASA/JPL-Caltech.

Astronomers using NASA's Spitzer and Hubble space telescopes have probed the stormy atmosphere of a brown dwarf, creating the most detailed "weather map" yet for this class of cool, star-like orbs. The forecast shows wind-driven, planet-sized clouds enshrouding these strange worlds.

Brown dwarfs form out of condensing gas, as stars do, but lack the mass to fuse hydrogen atoms and produce energy. Instead, these objects, which some call failed stars, are more similar to gas planets with their complex, varied atmospheres. The new research is a stepping-stone toward a better understanding not only of brown dwarfs, but also of the atmospheres of planets beyond our solar system.

This artist's illustration shows the atmosphere of a brown dwarf called 2MASSJ22282889-431026, which was observed simultaneously by NASA's Spitzer and Hubble space telescopes. Image credit: NASA/JPL-Caltech.

"With Hubble and Spitzer, we were able to look at different atmospheric layers of a brown dwarf, similar to the way doctors use medical imaging techniques to study the different tissues in your body," said Daniel Apai, the principal investigator of the research at the University of Arizona in Tucson, who presented the results at the American Astronomical Society meeting Tuesday in Long Beach, Calif.

A study describing the results, led by Esther Buenzli, also of the University of Arizona, is published in the Astrophysical Journal Letters.

The researchers turned Hubble and Spitzer simultaneously toward a brown dwarf with the long name of 2MASSJ22282889-431026. They found that its light varied in time, brightening and dimming about every 90 minutes as the body rotated. But more surprising, the team also found the timing of this change in brightness depended on whether they looked using different wavelengths of infrared light.

This graph shows the brightness variations of the brown dwarf named 2MASSJ22282889-431026 measured simultaneously by both NASA’s Hubble and Spitzer space telescopes. Image credit: NASA/JPL-Caltech/University of Arizona.

These variations are the result of different layers or patches of material swirling around the brown dwarf in windy storms as large as Earth itself. Spitzer and Hubble see different atmospheric layers because certain infrared wavelengths are blocked by vapors of water and methane high up, while other infrared wavelengths emerge from much deeper layers.

"Unlike the water clouds of Earth or the ammonia clouds of Jupiter, clouds on brown dwarfs are composed of hot grains of sand, liquid drops of iron, and other exotic compounds," said Mark Marley, research scientist at NASA's Ames Research Center in Moffett Field, Calif., and co-author of the paper. "So this large atmospheric disturbance found by Spitzer and Hubble gives a new meaning to the concept of extreme weather."

Buenzli says this is the first time researchers can probe variability at several different altitudes at the same time in the atmosphere of a brown dwarf. "Although brown dwarfs are cool relative to other stars, they are actually hot by earthly standards. This particular object is about 1,100 to 1,300 degrees Fahrenheit (600 to 700 degrees Celsius)," Buenzli said.

Spitzer Space Telescope. Image credit: NASA.

"What we see here is evidence for massive, organized cloud systems, perhaps akin to giant versions of the Great Red Spot on Jupiter," said Adam Showman, a theorist at the University of Arizona involved in the research. "These out-of-sync light variations provide a fingerprint of how the brown dwarf's weather systems stack up vertically. The data suggest regions on the brown dwarf where the weather is cloudy and rich in silicate vapor deep in the atmosphere coincide with balmier, drier conditions at higher altitudes -- and vice versa."

Researchers plan to look at the atmospheres of dozens of additional nearby brown dwarfs using Spitzer and Hubble.

Hubble Space Telescope. Image credit: NASA / ESA

"From studies such as this we will learn much about this important class of objects, whose mass falls between that of stars and Jupiter-sized planets," said Glenn Wahlgren, Spitzer program scientist at NASA Headquarters in Washington. "This technique will see extensive use when we are able to image individual exoplanets."

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 in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit and .

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington. For more information about Hubble, visit and .

Images (mentioned), Text, Credits: NASA / J.D. Harrington / ESA / JPL / Whitney Clavin.

Best regards,

SOFIA Spots Recent Starbursts in the Milky Way Galaxy's Center

NASA / DLR - SOFIA Mission patch / ESA - Hubble Space Telescope logo.

January 9, 2013

SOFIA/FORCAST mid-infrared image of the Milky Way galaxy’s nucleus showing the Circumnuclear Ring (CNR) of gas and dust clouds orbiting a central supermassive black hole. The bright Y-shaped feature is believed to be material falling from the ring toward the black hole that is located where the arms of the “Y” intersect. (NASA/SOFIA/FORCAST team/Lau et al. ).

Researchers using the Stratospheric Observatory for Infrared Astronomy (SOFIA) have captured new images of a ring of gas and dust seven light-years in diameter surrounding the supermassive black hole at the center of the Milky Way, and of a neighboring cluster of extremely luminous young stars embedded in dust cocoons.

Hubble Space Telescope/NICMOS near-infrared image showing the same field of view with the same scale and orientation as the image above. At this wavelength, opaque dust in the plane of the Milky Way hides features that are seen in the SOFIA image. (NASA/STScI).

The images of our galaxy's circumnuclear ring (CNR) and its neighboring quintuplet cluster (QC) are the subjects of two posters presented this week during the American Astronomical Society's meeting in Long Beach, Calif. Ryan Lau of Cornell University and his collaborators studied the CNR. Matt Hankins of the University of Central Arkansas in Conway is lead author of the other paper, regarding the QC.

SOFIA/FORCAST mid-infrared image of a region including the Quintuple Cluster (QC), a group of young stars near the left margin of the frame, located about 35 parsecs (100 light years) from the galaxy’s nucleus. (NASA/SOFIA/Hankins et al.).

SOFIA is a highly modified Boeing 747SP aircraft carrying a telescope with an effective diameter of 100 inches (2.54 meters) to altitudes as high as 45,000 feet (13.7 kilometers).

Hubble Space Telescope/NICMOS image of the QC region matching the SOFIA/FORCAST field of view in the third image above. The QC itself is at the left of the frame. Most of the features in the SOFIA mid-infrared image are not seen in the HST image due to their low temperatures and intervening interstellar dust. (NASA/STScI).

The images were obtained during SOFIA flights in 2011 with the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) instrument built by a team with principal investigator Terry Herter of Cornell.

FORCAST offered astronomers the ability to see the CNR and QC regions and other exotic cosmic features whose light is obscured by water vapor in Earth's atmosphere and interstellar dust clouds in the mid-plane of the Milky Way. Neither ground-based observatories on tall mountain peaks nor NASA's orbiting Hubble and Spitzer space telescopes can see them.

Stratospheric Observatory for Infrared Astronomy (SOFIA). NASA / DLR

The images may be seen by visiting: or

Each image is a combination of multiple exposures at wavelengths of 20, 32, and 37 microns.

Figure 1a shows the CNR and Figure 2a shows the QC. The CNR and other exotic features revealed by SOFIA's FORCAST camera are invisible to Hubble's near-infrared camera, as shown for comparison in figures 1b and 2b. Figure 3 shows the two fields studied in these papers as square insets on a large-scale image of the galactic center made by the Spitzer Space Telescope at a wavelength of 8 microns.

Hubble Space Telescope. Image credit: NASA / ESA.

"The focus of our study has been to determine the structure of the circumnuclear ring with the unprecedented precision possible with SOFIA" said Lau. "Using these data we can learn about the processes that accelerate and heat the ring."

The nucleus of the Milky Way is inhabited by a black hole with 4 million times the mass of the sun and is orbited by a large disk of gas and dust. The ring seen in Figure 1a is the inner edge of that disk. The galactic center also hosts several exceptionally large star clusters containing some of the most luminous young stars in the galaxy, one of which is the Quintuplet Cluster seen in Figure 2. The combination of SOFIA's airborne telescope with the FORCAST camera produced the sharpest images of those regions ever obtained at mid-infrared wavelengths, allowing discernment of new clues about what is happening near the central black hole.

"Something big happened in the Milky Way's center within the past 4 million to 6 million years which resulted in several bursts of star formation, creating the Quintuplet Cluster, the Central Cluster, and one other massive star cluster." said Hankins, lead author of the QC paper. "Many other galaxies also have so-called 'starbursts' in their central regions, some associated with central black holes, some not. The Milky Way's center is much nearer than other galaxies, making it easier for us to explore possible connections between the starbursts and the black hole."

SOFIA Chief Scientific Advisor Eric Becklin, who is working with the CNR group, determined the location of the galaxy's nucleus as a graduate student in the 1960s by laboriously scanning a single-pixel infrared detector to map the central region.

"The resolution and spatial coverage of these images is astounding, showing what modern infrared detector arrays can do when flown on SOFIA," Becklin said. "We hope to use these data to substantially advance our understanding of the environment near a supermassive black hole."

SOFIA is a joint project of NASA and the German Aerospace Center. SOFIA is based and managed at NASA's Dryden Aircraft Operations Facility in Palmdale, Calif. NASA's Ames Research Center in Moffett Field, Calif., manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Md., and the German SOFIA Institute at the University of Stuttgart.

For information about SOFIA and its science mission, visit:

Images (mentioned), Text, Credits: NASA / ESA / DLR.


NASA, ESA Telescopes Find Evidence for Asteroid Belt Around Vega

NASA - Spitzer Space Telescope patch / ESA - Herschel Mission patch.

Jan. 9, 2013

This artist's concept illustrates an asteroid belt around the bright star Vega. Image credit: NASA/JPL-Caltech.

Astronomers have discovered what appears to be a large asteroid belt around the star Vega, the second brightest star in northern night skies. The scientists used data from NASA's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory, in which NASA plays an important role.

The discovery of an asteroid belt-like band of debris around Vega makes the star similar to another observed star called Fomalhaut. The data are consistent with both stars having inner, warm belts and outer, cool belts separated by a gap. This architecture is similar to the asteroid and Kuiper belts in our own solar system.

What is maintaining the gap between the warm and cool belts around Vega and Fomalhaut? The results strongly suggest the answer is multiple planets. Our solar system's asteroid belt, which lies between Mars and Jupiter, is maintained by the gravity of the terrestrial planets and the giant planets, and the outer Kuiper belt is sculpted by the giant planets.

"Our findings echo recent results showing multiple-planet systems are common beyond our sun," said Kate Su, an astronomer at the Steward Observatory at the University of Arizona, Tucson. Su presented the results Tuesday at the American Astronomical Society meeting in Long Beach, Calif., and is lead author of a paper on the findings accepted for publication in the Astrophysical Journal.

Image above: Astronomers have discovered what appears to be a large asteroid belt around the bright star Vega, as illustrated here at left in brown. Image credit: NASA/JPL-Caltech.

Vega and Fomalhaut are similar in other ways. Both are about twice the mass of our sun and burn a hotter, bluer color in visible light. Both stars are relatively nearby, at about 25 light-years away. The stars are thought to be around 400 million years old, but Vega could be closer to its 600 millionth birthday. Fomalhaut has a single candidate planet orbiting it, Fomalhaut b, which orbits at the inner edge of its cometary belt.

The Herschel and Spitzer telescopes detected infrared light emitted by warm and cold dust in discrete bands around Vega and Fomalhaut, discovering the new asteroid belt around Vega and confirming the existence of the other belts around both stars. Comets and the collisions of rocky chunks replenish the dust in these bands. The inner belts in these systems cannot be seen in visible light because the glare of their stars outshines them.

Spitzer Space Telescope. Image credit: NASA/JPL-Caltech

Both the inner and outer belts contain far more material than our own asteroid and Kuiper belts. The reason is twofold: the star systems are far younger than our own, which has had hundreds of millions more years to clean house, and the systems likely formed from an initially more massive cloud of gas and dust than our solar system.

The gap between the inner and outer debris belts for Vega and Fomalhaut also proportionally corresponds to the distance between our sun's asteroid and Kuiper belts. This distance works out to a ratio of about 1:10, with the outer belt 10 times farther from its host star than the inner belt. As for the large gap between the two belts, it is likely there are several undetected planets, Jupiter-size or smaller, creating a dust-free zone between the two belts. A good comparison star system is HR 8799, which has four known planets that sweep up the space between two similar disks of debris.

Herschel Space Telescope. Image credit: NAS / ESA.

"Overall, the large gap between the warm and the cold belts is a signpost that points to multiple planets likely orbiting around Vega and Fomalhaut," said Su.

If unseen planets do, in fact, orbit Vega and Fomalhaut, these bodies will not likely stay hidden.

"Upcoming new facilities such as NASA's James Webb Space Telescope should be able to find the planets," said paper co-author Karl Stapelfeldt, chief of the Exoplanets and Stellar Astrophysics Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md.

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 in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit: and .

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at JPL, which contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at Caltech, supports the United States astronomical community. More information is online at: , , and .

You can follow JPL News on Facebook at: and on Twitter at: .

Images (mentioned), Text, Credits: NASA / J.D. Harrington / ESA / JPL / Whitney Clavin.


NASA's Big Mars Rover Makes First Use of its Brush

NASA - Mars Science Laboratory (MSL) logo.

Jan. 8, 2013

This image from the Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). Image credit: NASA/JPL-Caltech/MSSS.

NASA's Mars rover Curiosity has completed first-time use of a brush it carries to sweep dust off rocks.

Nearing the end of a series of first-time uses of the rover's tools, the mission has cleared dust away from a targeted patch on a flat Martian rock using the Dust Removal Tool.

The tool is a motorized, wire-bristle brush designed to prepare selected rock surfaces for enhanced inspection by the rover's science instruments. It is built into the turret at the end of the rover's arm. In particular, the Alpha Particle X-ray Spectrometer and the Mars Hand Lens Imager, which share the turret with the brush and the rover's hammering drill, can gain information after dust removal that would not be accessible from a dust-blanketed rock.

Choosing an appropriate target was crucial for the first-time use of the Dust Removal Tool. The chosen target, called "Ekwir_1," is on a rock in the "Yellowknife Bay" area of Mars' Gale Crater. The rover team is also evaluating rocks in that area as potential targets for first use of the rover's hammering drill in coming weeks.

This image from the Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity shows details of rock texture and color in an area where the rover's Dust Removal Tool (DRT) brushed away dust that was on the rock. Image credit: NASA/JPL-Caltech/MSSS.

Images of the brushed area on Ekwir are online at and .

"We wanted to be sure we had an optimal target for the first use," said Diana Trujillo of NASA's Jet Propulsion Laboratory, Pasadena, Calif., the mission's activity lead for the Dust Removal Tool. "We need to place the instrument within less than half an inch of the target without putting the hardware at risk. We needed a flat target, one that wasn't rough, one that was covered with dust. The results certainly look good."

Mars Science Laboratory (MSL). Image credit: NASA/JPL-Caltech

Honeybee Robotics, New York, N.Y., built the Dust Removal Tool for Curiosity, as well as tools for two previous Mars rovers, Spirit and Opportunity, which included wire brushes plus rock-grinding mechanisms.

NASA's Mars Science Laboratory project is using Curiosity to investigate whether the study area within Gale Crater has offered environmental conditions favorable for microbial life. JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory mission for the NASA Science Mission Directorate, Washington. For more information about the mission, visit and .

Follow the mission on Facebook at and on Twitter at .

Images (mentioned), Text, Credits: NASA / JPL / Guy Webster.


Cassini Suggests Icing on a Lake

NASA / ESA - Cassini-Huygens Mission to Saturn & Titan patch.

Jan. 8, 2013

This artist's concept envisions what hydrocarbon ice forming on a liquid hydrocarbon sea of Saturn's moon Titan might look like. Image credit: NASA/JPL-Caltech/USGS.

It's not exactly icing on a cake, but it could be icing on a lake. A new paper by scientists on NASA's Cassini mission finds that blocks of hydrocarbon ice might decorate the surface of existing lakes and seas of liquid hydrocarbon on Saturn's moon Titan. The presence of ice floes might explain some of the mixed readings Cassini has seen in the reflectivity of the surfaces of lakes on Titan.

"One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life," said Jonathan Lunine, a paper co-author and Cassini interdisciplinary Titan scientist at Cornell University, Ithaca, N.Y. "And the formation of floating hydrocarbon ice will provide an opportunity for interesting chemistry along the boundary between liquid and solid, a boundary that may have been important in the origin of terrestrial life."

Image above: Lakes on Saturn's moon Titan reflect radio waves in varying ways in this image from NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/ASI/Cornell.

Titan is the only other body besides Earth in our solar system with stable bodies of liquid on its surface. But while our planet's cycle of precipitation and evaporation involves water, Titan's cycle involves hydrocarbons like ethane and methane. Ethane and methane are organic molecules, which scientists think can be building blocks for the more complex chemistry from which life arose. Cassini has seen a vast network of these hydrocarbon seas cover Titan's northern hemisphere, while a more sporadic set of lakes bejewels the southern hemisphere.

Up to this point, Cassini scientists assumed that Titan lakes would not have floating ice, because solid methane is denser than liquid methane and would sink. But the new model considers the interaction between the lakes and the atmosphere, resulting in different mixtures of compositions, pockets of nitrogen gas, and changes in temperature. The result, scientists found, is that winter ice will float in Titan's methane-and-ethane-rich lakes and seas if the temperature is below the freezing point of methane -- minus 297 degrees Fahrenheit (90.4 kelvins). The scientists realized all the varieties of ice they considered would float if they were composed of at least 5 percent "air," which is an average composition for young sea ice on Earth. ("Air" on Titan has significantly more nitrogen than Earth air and almost no oxygen.)

If the temperature drops by just a few degrees, the ice will sink because of the relative proportions of nitrogen gas in the liquid versus the solid. Temperatures close to the freezing point of methane could lead to both floating and sinking ice – that is, a hydrocarbon ice crust above the liquid and blocks of hydrocarbon ice on the bottom of the lake bed. Scientists haven't entirely figured out what color the ice would be, though they suspect it would be colorless, as it is on Earth, perhaps tinted reddish-brown from Titan's atmosphere.

"We now know it's possible to get methane-and-ethane-rich ice freezing over on Titan in thin blocks that congeal together as it gets colder -- similar to what we see with Arctic sea ice at the onset of winter," said Jason Hofgartner, first author on the paper and a Natural Sciences and Engineering Research Council of Canada scholar at Cornell. "We'll want to take these conditions into consideration if we ever decide to explore the Titan surface some day."

Image above: Cassini spacecraft orbiting Titan phase release of the Huygens probe on Dec. 24, 2004. Image credit: NASA/JPL-Caltech.

Cassini's radar instrument will be able to test this model by watching what happens to the reflectivity of the surface of these lakes and seas. A hydrocarbon lake warming in the early spring thaw, as the northern lakes of Titan have begun to do, may become more reflective as ice rises to the surface. This would provide a rougher surface quality that reflects more radio energy back to Cassini, making it look brighter. As the weather turns warmer and the ice melts, the lake surface will be pure liquid, and will appear to the Cassini radar to darken.

"Cassini's extended stay in the Saturn system gives us an unprecedented opportunity to watch the effects of seasonal change at Titan," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We'll have an opportunity to see if the theories are right."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and ASI, the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington.

NASA - Cassini website:

ESA - Cassini-Huygens website:

Images (mentioned), Text, Credits: NASA / JPL / Jia-Rui Cook.


Vela Pulsar

NASA - Chandra X-ray Observatory patch.

Jan. 8, 2013

This movie from NASA's Chandra X-ray Observatory shows a fast moving jet of particles produced by a rapidly rotating neutron star, and may provide new insight into the nature of some of the densest matter in the universe.

The star of this movie is the Vela pulsar, a neutron star that was formed when a massive star collapsed. The Vela pulsar is about 1,000 light years from Earth, spansis about 12 miles in diameter, and makes over 11 complete rotations every second, faster than a helicopter rotor. As the pulsar whips around, it spews out a jet of charged particles that race out along the pulsar’s rotation axis at about 70% of the speed of light. In this still image from the movie, the location of the pulsar and the 0.7-light-year-long jet are labeled.

The Chandra data shown in the movie, containing eight images obtained between June and September 2010, suggest that the pulsar may be slowly wobbling, or precessing, as it spins. The shape and the motion of the Vela jet look strikingly like a rotating helix, a shape that is naturally explained by precession, as shown in this animation [link to mathematica animation from Oleg K]. If the evidence for precession of the Vela pulsar is confirmed, it would be the first time that a jet from a neutron star has been found to be wobbling, or precessing, in this way.

One possible cause of precession for a spinning neutron star is that it has become slightly distorted and is no longer a perfect sphere. This distortion might be caused by the combined action of the fast rotation and "glitches", sudden increases of the pulsar's rotational speed due to the interaction of the superfluid core of the neutron star with its crust.

A paper describing these results will be published in The Astrophysical Journal on January 10, 2013.

Chandra Captures Neutron Star Action

This is the second Chandra movie of the Vela pulsar, with the original having been released in 2003. The first Vela movie contained shorter, unevenly spaced observations so that the changes in the jet were less pronounced and the authors did not argue that precession was occurring. However, based on the same data, Avinash Deshpande of Arecibo Observatory in Puerto Rico and the Raman Research Institute in Bangalore, India, and the late Venkatraman Radhakrishnan, argued in a 2007 paper that the Vela pulsar might be precessing.

The Earth also precesses as it spins, with a period of about 26,000 years. In the future Polaris will no longer be the "north star" and other stars will take its place. The period of the Vela precession is much shorter and is estimated to be about 120 days.

 Chandra X-ray Observatory

The supernova that formed the Vela pulsar exploded over 10,000 years ago. This optical image from the Anglo-Australian Observatory's UK Schmidt telescope shows the enormous apparent size of the supernova remnant formed by the explosion. The full size of the remnant is about eight degrees across, or about 16 times the angular size of the moon. The square near the center shows the Chandra image with a larger field-of-view than used for the movie, with the Vela pulsar in the middle.

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Images, Video, Text, Credits: X-ray: NASA / CXC / Univ of Toronto / M.Durant et al; Optical: DSS / Davide De Martin.

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