Tuesday, April 30, 2013

NGC 6240: Colossal Hot Cloud Envelopes Colliding Galaxies

NGC 6240

Credit: X-ray (NASA/CXC/SAO/E.Nardini et al); Optical (NASA/STScI)





Scientists have used Chandra to make a detailed study of an enormous cloud of hot gas enveloping two large, colliding galaxies. This unusually large reservoir of gas contains as much mass as 10 billion Suns, spans about 300,000 light years, and radiates at a temperature of more than 7 million degrees Kelvin.

This giant gas cloud, which scientists call a "halo," is located in the system called NGC 6240. Astronomers have long known that NGC 6240 is the site of the merger of two large spiral galaxies similar in size to our own Milky Way. Each galaxy contains a supermassive black hole at its center. The black holes are spiraling toward one another, and may eventually merge to form a larger black hole. 

Another consequence of the collision between the galaxies is that the gas contained in each individual galaxy has been violently stirred up. This caused a baby boom of new stars that has lasted for at least 200 million years. During this burst of stellar birth, some of the most massive stars raced through their evolution and exploded relatively quickly as supernovas.

The scientists involved with this study argue that this rush of supernova explosions dispersed relatively high amounts of important elements such as oxygen, neon, magnesium, and silicon into the hot gas of the newly combined galaxies. According to the researchers, the data suggest that this enriched gas has slowly expanded into and mixed with cooler gas that was already there.

During the extended baby boom, shorter bursts of star formation have occurred. For example, the most recent burst of star formation lasted for about five million years and occurred about 20 million years ago in Earth's timeframe. However, the authors do not think that the hot gas was produced just by this shorter burst.

What does the future hold for observations of NGC 6240? Most likely the two spiral galaxies will form one young elliptical galaxy galaxy over the course of millions of years. It is unclear, however, how much of the hot gas can be retained by this newly formed galaxy, rather than lost to surrounding space. Regardless, the collision offers the opportunity to witness a relatively nearby version of an event that was common in the early Universe when galaxies were much closer together and merged more often.

In this new composite image of NGC 6240, the X-rays from Chandra that reveal the hot gas cloud are colored purple. These data have been combined with optical data from the Hubble Space Telescope, which shows long tidal tails from the merging galaxies, extending to the right and bottom of the image.

A paper describing these new results on NGC 6240 is available online and appeared in the March 10, 2013 issue of The Astrophysical Journal. The authors in this study were Emanuele Nardini (Harvard-Smithsonian Center for Astrophysics, or CfA, Cambridge, MA and currently at Keele University, UK), Junfeng Wang (CfA and currently at Northwestern University, Evanston, IL), Pepi Fabbiano (CfA), Martin Elvis (CfA), Silvia Pellegrini (University of Bologna, Italy), Guido Risalti (INAF-Osservatorio Astrofisico di Arcetri, Italy and CfA), Margarita Karovska (CfA), and Andreas Zezas (University of Crete, Greece and CfA).
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.


Fast Facts for NGC 6240: 

Scale: Image is 3 arcmin across (About 290,000 light years)
Category: Black Holes, Normal Galaxies & Starburst Galaxies
Coordinates (J2000): RA 16h 52m 59s | Dec +02° 24' 01.70"
Constellation: Ophiuchus
Observation Date: 4 pointings between July 2001 and May 2011
Observation Time: 136 hours 6 min (5 days 16 hours 6 min)
Obs. ID: 1590, 6908, 6909, 12713
Instrument:  ACIS
References: Nardini, E et al, 2012, ApJ 765, 141; arXiv:1301.5907
Color Code: X-ray (Purple); Optical (Red, Green, Blue)
Distance Estimate: About 330 million light years (redshift = 0.0245) 


Monday, April 29, 2013

NASA Probe Gets Close Views of Large Saturn Hurricane


Narrated video about a hurricane-like storm seen at Saturn's north pole by NASA's Cassini spacecraft.  › Download video       › Related video

The spinning vortex of Saturn's north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/SSI.  › Full image and caption

The north pole of Saturn, in the fresh light of spring, is revealed in this color image from NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/SSI.  › Full image and caption

This spectacular, vertigo inducing, false-color image from NASA's Cassini mission highlights the storms at Saturn's north pole. Image credit: NASA/JPL-Caltech/SSI. › Full image and caption 

PASADENA, Calif. - NASA's Cassini spacecraft has provided scientists the first close-up, visible-light views of a behemoth hurricane swirling around Saturn's north pole. 

In high-resolution pictures and video, scientists see the hurricane's eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than the average hurricane eye on Earth. Thin, bright clouds at the outer edge of the hurricane are traveling 330 mph(150 meters per second). The hurricane swirls inside a large, mysterious, six-sided weather pattern known as the hexagon. 

"We did a double take when we saw this vortex because it looks so much like a hurricane on Earth," said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. "But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn's hydrogen atmosphere."
Scientists will be studying the hurricane to g
ain insight into hurricanes on Earth, which feed off warm ocean water. Although there is no body of water close to these clouds high in Saturn's atmosphere, learning how these Saturnian storms use water vapor could tell scientists more about how terrestrial hurricanes are generated and sustained. 

Both a terrestrial hurricane and Saturn's north polar vortex have a central eye with no clouds or very low clouds. Other similar features include high clouds forming an eye wall, other high clouds spiraling around the eye, and a counter-clockwise spin in the northern hemisphere. 

A major difference between the hurricanes is that the one on Saturn is much bigger than its counterparts on Earth and spins surprisingly fast. At Saturn, the wind in the eye wall blows more than four times faster than hurricane-force winds on Earth. Unlike terrestrial hurricanes, which tend to move, the Saturnian hurricane is locked onto the planet's north pole. On Earth, hurricanes tend to drift northward because of the forces acting on the fast swirls of wind as the planet rotates. The one on Saturn does not drift and is already as far north as it can be. 

"The polar hurricane has nowhere else to go, and that's likely why it's stuck at the pole," said Kunio Sayanagi, a Cassini imaging team associate at Hampton University in Hampton, Va. 

Scientists believe the massive storm has been churning for years. When Cassini arrived in the Saturn system in 2004, Saturn's north pole was dark because the planet was in the middle of its north polar winter. During that time, the Cassini spacecraft's composite infrared spectrometer and visual and infrared mapping spectrometer detected a great vortex, but a visible-light view had to wait for the passing of the equinox in August 2009. Only then did sunlight begin flooding Saturn's northern hemisphere. The view required a change in the angle of Cassini's orbits around Saturn so the spacecraft could see the poles. 

"Such a stunning and mesmerizing view of the hurricane-like storm at the north pole is only possible because Cassini is on a sportier course, with orbits tilted to loop the spacecraft above and below Saturn's equatorial plane," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "You cannot see the polar regions very well from an equatorial orbit. Observing the planet from different vantage points reveals more about the cloud layers that cover the entirety of the planet." 

Cassini changes its orbital inclination for such an observing campaign only once every few years. Because the spacecraft uses flybys of Saturn's moon Titan to change the angle of its orbit, the inclined trajectories require attentive oversight from navigators. The path requires careful planning years in advance and sticking very precisely to the planned itinerary to ensure enough propellant is available for the spacecraft to reach future planned orbits and encounters. 

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the United States, the United Kingdom, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo. 

For more information about Cassini and its mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .


Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington

dwayne.c.brown@nasa.gov

 

Herschel closes its eyes on the Universe

Copyright: ESA/PACS & SPIRE Consortia, T. Hill, F. Motte, Laboratoire AIM Paris-Saclay, CEA/IRFU – CNRS/INSU – Uni. Paris Diderot, HOBYS Key Programme Consortium

ESA’s Herschel space observatory has exhausted its supply of liquid helium coolant, ending more than three years of pioneering observations of the cool Universe.

The event was not unexpected: the mission began with over 2300 litres of liquid helium, which has been slowly evaporating since the final top-up the day before Herschel’s launch on 14 May 2009.

The liquid helium was essential to cool the observatory’s instruments to close to absolute zero, allowing Herschel to make highly sensitive observations of the cold Universe until today.

The confirmation that the helium is finally exhausted came this afternoon at the beginning of the spacecraft’s daily communication session with its ground station in Western Australia, with a clear rise in temperatures measured in all of Herschel’s instruments.

“Herschel has exceeded all expectations, providing us with an incredible treasure trove of data that that will keep astronomers busy for many years to come,” says Prof. Alvaro Giménez Cañete, ESA’s Director of Science and Robotic Exploration.

Herschel has made over 35 000 scientific observations, amassing more than 25 000 hours’ worth of science data from about 600 observing programmes. A further 2000 hours of calibration observations also contribute to the rich dataset, which is based at ESA’s European Space Astronomy Centre, near Madrid in Spain. 

The archive will become the legacy of the mission. It is expected to provide even more discoveries than have been made during the lifetime of the Herschel mission. 

“Herschel’s ground-breaking scientific haul is in no little part down to the excellent work done by European industry, institutions and academia in developing, building and operating the observatory and its instruments,” says Thomas Passvogel, ESA’s Herschel Programme Manager. 

“Herschel has offered us a new view of the hitherto hidden Universe, pointing us to a previously unseen process of star birth and galaxy formation, and allowing us to trace water through the Universe from molecular clouds to newborn stars and their planet-forming discs and belts of comets,” says Göran Pilbratt, ESA’s Herschel Project Scientist. 

Copyright: ESA/Herschel/SPIRE/PACS/D. Arzoumanian (CEA Saclay) for the “Gould Belt survey” Key Programme Consortium.

Star birth

Herschel’s stunning images of intricate networks of dust and gas filaments within our Milky Way Galaxy provide an illustrated history of star formation. These unique far-infrared observations have given astronomers a new insight into how turbulence stirs up gas in the interstellar medium, giving rise to a filamentary, web-like structure within cold molecular clouds. 

If conditions are right, gravity then takes over and fragments the filaments into compact cores. Deeply embedded inside these cores are protostars, the seeds of new stars that have gently heated their surrounding dust to just a few degrees above absolute zero, revealing their locations to Herschel’s heat-sensitive eyes. 

Herschel’s image of Fomalhaut
Copyright: ESA/Herschel/PACS/Bram Acke, KU Leuven, Belgium

Following the water Trail

Over the first few million years in the life of newborn stars, the formation of planets can be followed in the dense discs of gas and dust swirling around them. In particular, Herschel has been following the trail of water, a molecule crucial to life as we know it, from star-formation clouds to stars to planet-forming discs. 

Herschel has detected thousands of Earth ocean’s worth of water vapour in these discs, with even greater quantities of ice locked up on the surface of dust grains and in comets. 

Closer to home, Herschel has also studied the composition of the water-ice in Comet Hartley-2, finding it to have almost exactly the same isotopic ratios as the water in our oceans. 

These findings fuel the debate about how much of Earth’s water was delivered via impacting comets. Combined with the observations of massive comet belts around other stars, astronomers hope to understand whether a similar mechanism could be in play in other planetary systems, too.
 
Copyright: ESA–C. Carreau/C. Casey (University of Hawai'i); COSMOS field: ESA/Herschel/SPIRE/HerMES Key Programme; Hubble images: NASA, ESA

Galaxies across the Universe

Herschel has also contributed to our knowledge of star formation on the grandest scales, spanning much of cosmic space and time. By studying star formation in distant galaxies, it has identified many that are forming stars at prodigious rates, even in the early years of the Universe’s 13.8 billion-year life.

These intense star-forming galaxies produce hundreds to thousands of solar masses’ worth of stars each year. By comparison, our own Milky Way Galaxy produces the equivalent of only one Sun-like star per year on average. 

How galaxies can support star formation on such massive scales during the first few billions of years of the Universe’s existence poses a crucial problem for scientists studying galaxy formation and evolution. 

Herschel observations are hinting that when the Universe was young, galaxies had much more gas to feed from, enabling high rates of star formation even in the absence of the collisions between galaxies normally needed to spark these spectacular bouts of star birth. 

“Although this is the end of Herschel observing, it is certainly not the end of the mission – there are plenty more discoveries to come,” says Dr Pilbratt. 

“We will now spend the next few years making our data accessible in the form of the best possible maps, spectra and various catalogues to support the work of present and future astronomers. Nevertheless, we’re sad to see the end of this phase: thank you, Herschel!” 

 Notes for Editors

ESA’s Herschel space observatory was launched on 14 May 2009 and, with a primary mirror 3.5 m across, is the largest, most powerful infrared telescope ever flown in space. 

Its two camera/imaging spectrometers, PACS (Photoconductor Array Camera and Spectrometer) and SPIRE (Spectral and Photometric Imaging Receiver), together covered wavelengths of 55–670 microns. 

A third science instrument, HIFI (Heterodyne Instrument for the Far Infrared), a very high resolution spectrometer, covered two wavelength bands, 157–212 microns and 240–625 microns. All three instruments were cooled to –271ºC inside a cryostat filled with liquid superfluid helium. The mission finally exhausted its coolant today. 

Herschel will continue communicating with its ground stations for some time now that the helium is exhausted, during which a range of technical tests will be performed. 

Finally, in May, it will be propelled into its long-term stable parking orbit around the Sun. 

In addition to the legacy of the scientific data, the mission resulted in a number of technology advances applicable to future ESA missions. Herschel saw the development of advanced cryogenic systems, the construction of the largest mirror ever flown in space, and the most sensitive direct detectors for light in the far-infrared to millimetre range. 

Manufacturing techniques have already been applied to the next generation of ESA’s space missions, including Gaia and the James Webb Space Telescope. 

For further information, please contact:
 
Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer@esa.int

Göran Pilbratt
ESA Herschel Project Scientist
Tel: +31 71 565 3621
Email: gpilbratt@rssd.esa.int


Friday, April 26, 2013

NASA Probe Observes Meteors Colliding with Saturn's Rings

  
Five images of Saturn's rings, taken by NASA's Cassini spacecraft between 2009 and 2012, show clouds of material ejected from impacts of small objects into the rings. Image Credit: NASA/JPL-Caltech/Space Science Institute/Cornell.  › Full image and caption

PASADENA, Calif. -- NASA's Cassini spacecraft has provided the first direct evidence of small meteoroids breaking into streams of rubble and crashing into Saturn's rings.

These observations make Saturn's rings the only location besides Earth, the moon and Jupiter where scientists and amateur astronomers have been able to observe impacts as they occur. Studying the impact rate of meteoroids from outside the Saturnian system helps scientists understand how different planet systems in our solar system formed.

The solar system is full of small, speeding objects. These objects frequently pummel planetary bodies. The meteoroids at Saturn are estimated to range from about one-half inch to several yards (1 centimeter to several meters) in size. It took scientists years to distinguish tracks left by nine meteoroids in 2005, 2009 and 2012.

Details of the observations appear in a paper in the Thursday, April 25 edition of Science.

Results from Cassini have already shown Saturn's rings act as very effective detectors of many kinds of surrounding phenomena, including the interior structure of the planet and the orbits of its moons. For example, a subtle but extensive corrugation that ripples 12,000 miles (19,000 kilometers) across the innermost rings tells of a very large meteoroid impact in 1983.

"These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth -- two very different neighborhoods in our solar system -- and this is exciting to see," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It took Saturn's rings acting like a giant meteoroid detector -- 100 times the surface area of the Earth -- and Cassini's long-term tour of the Saturn system to address this question."

The Saturnian equinox in summer 2009 was an especially good time to see the debris left by meteoroid impacts. The very shallow sun angle on the rings caused the clouds of debris to look bright against the darkened rings in pictures from Cassini's imaging science subsystem.

"We knew these little impacts were constantly occurring, but we didn't know how big or how frequent they might be, and we didn't necessarily expect them to take the form of spectacular shearing clouds," said Matt Tiscareno, lead author of the paper and a Cassini participating scientist at Cornell University in Ithaca, N.Y. "The sunlight shining edge-on to the rings at the Saturnian equinox acted like an anti-cloaking device, so these usually invisible features became plain to see."

Tiscareno and his colleagues now think meteoroids of this size probably break up on a first encounter with the rings, creating smaller, slower pieces that then enter into orbit around Saturn. The impact into the rings of these secondary meteoroid bits kicks up the clouds. The tiny particles forming these clouds have a range of orbital speeds around Saturn. The clouds they form soon are pulled into diagonal, extended bright streaks.

"Saturn's rings are unusually bright and clean, leading some to suggest that the rings are actually much younger than Saturn," said Jeff Cuzzi, a co-author of the paper and a Cassini interdisciplinary scientist specializing in planetary rings and dust at NASA's Ames Research Center in Moffett Field, Calif. "To assess this dramatic claim, we must know more about the rate at which outside material is bombarding the rings. This latest analysis helps fill in that story with detection of impactors of a size that we weren't previously able to detect directly."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For images of the impacts and information about Cassini, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov


Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown 202-358-1726
NASA Headquarters, Washington


A changing fan

Credit: ESA/Hubble & NASA.
Acknowledgement: Alexey Romashin

The Universe is rarely static, although the timescales involved can be very long. Since modern astronomical observations began we have been observing the birthplaces of new stars and planets, searching for and studying the subtle changes that help us to figure out what is happening within.

The bright spot located at the edge of the bluish fan-shaped structure in this Hubble image is a young star called V* PV Cephei, or PV Cep. It is a favourite target for amateur astronomers because the fan-shaped nebulosity, known as GM 1-29 or Gyulbudaghian’s Nebula, changes over a timescale of months. The brightness of the star has also varied over time.

Images of PV Cep taken in 1952 showed a nebulous streak, similar to a comet’s tail. However, these had vanished when new images of the star were obtained some twenty-five years later. Instead, the blue fan-shaped nebula had appeared. Twenty-five years is a very short period on cosmic timescales, so astronomers think that the mysterious streak may have been a temporary phenomenon, such as the remnants of a massive stellar flare — similar to the solar flares we are used to seeing in the Solar System.

At the same time as this was happening, the star itself was brightening. This provided the light to illuminate the newly formed fan-shaped nebula. This brightening might be related to the start of the hydrogen-burning phase of the star, which would mean that it was reaching maturity.

PV Cep is thought to be surrounded by a disc of gas and dust, which would stop light from escaping in all directions. The fan-like appearance is therefore probably a result of starlight escaping from the dust disc and projecting onto the nebula.

PV Cep is located in the northern constellation of Cepheus at a distance of over 1600 light-years from Earth.
A version of this image was entered into the Hubble’s Hidden Treasures competition by contestant Alexey Romashin.





Thursday, April 25, 2013

Einstein Was Right — So Far

 
Artist’s impression of the pulsar PSR J0348+0432 and its white dwarf companion
Artist’s impression of the pulsar PSR J0348+0432 and its white dwarf companion
Artist’s impression of the pulsar PSR J0348+0432 and its white dwarf companion


Videos 

Artist’s impression of the pulsar PSR J0348+0432 and its white dwarf companion
Artist’s impression of the pulsar PSR J0348+0432 and its white dwarf companion


Record-breaking pulsar takes tests of general relativity into new territory 

Astronomers have used ESO’s Very Large Telescope, along with radio telescopes around the world, to find and study a bizarre stellar pair consisting of the most massive neutron star confirmed so far, orbited by a white dwarf star. This strange new binary allows tests of Einstein’s theory of gravity — general relativity — in ways that were not possible up to now. So far the new observations exactly agree with the predictions from general relativity and are inconsistent with some alternative theories. The results will appear in the journal Science on 26 April 2013.

An international team has discovered an exotic double object that consists of a tiny, but unusually heavy neutron star that spins 25 times each second, orbited every two and a half hours by a white dwarf star. The neutron star is a pulsar that is giving off radio waves that can be picked up on Earth by radio telescopes. Although this unusual pair is very interesting in its own right it is also a unique laboratory for testing the limits of physical theories.

This pulsar is named PSR J0348+0432 and is the remains of a supernova explosion. It is twice as heavy as the Sun, but just 20 kilometres across. The gravity at its surface is more than 300 billion times stronger than that on Earth and at its centre every sugar-cubed-sized volume has more than one billion tonnes of matter squeezed into it. Its companion white dwarf star is only slightly less exotic; it is the glowing remains of a much lighter star that has lost its atmosphere and is slowly cooling.

I was observing the system with ESO’s Very Large Telescope, looking for changes in the light emitted from the white dwarf caused by its motion around the pulsar,” says John Antoniadis, a PhD student at the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn and lead author of the paper. “A quick on-the-spot analysis made me realise that the pulsar was quite a heavyweight. It is twice the mass of the Sun, making it the most massive neutron star that we know of and also an excellent laboratory for fundamental physics.”

Einstein’s general theory of relativity, which explains gravity as a consequence of the curvature of spacetime created by the presence of mass and energy, has withstood all tests since it was first published almost a century ago. But it cannot be the final explanation and must ultimately break down [1].

Physicists have devised other theories of gravity that make different predictions from general relativity. For some of these alternatives, these differences would only show up in extremely strong gravitational fields that cannot be found in the Solar System. In terms of gravity, PSR J0348+0432 is a truly extreme object, even compared to the other pulsars that have been used in high precision tests of Einstein’s general relativity [2]. In such strong gravitational fields small increases in the mass can lead to large changes in the spacetime around such objects. Up to now astronomers had no idea what would happen in the presence of such a massive neutron star as PSR J0348+0432. It offers the unique opportunity to push tests into new territory.

The team combined Very Large Telescope observations of the white dwarf with very precise timing of the pulsar from radio telescopes [3]. Such a close binary radiates gravitational waves and loses energy. This causes the orbital period to change very slightly and the predictions for this change from general relativity and other competing theories are different.

Our radio observations were so precise that we have already been able to measure a change in the orbital period of 8 millionths of a second per year, exactly what Einstein’s theory predicts,” states Paulo Freire, another team member.

This is just the start of detailed studies of this unique object and astronomers will be using it to test general relativity to ever greater precision as time goes on.

Notes

[1] General relativity is not consistent with the other great theory of twentieth century physics, quantum mechanics. It also predicts singularities under some circumstances, where some quantities tend to infinity, such as the centre of a black hole.

[2] The first binary pulsar, PSR B1913+16, was discovered by Joseph Hooton Taylor, Jr. and Russell Hulse, for which they won the 1993 Nobel Prize in Physics. They accurately measured the changes in the properties of this remarkable object and showed that they were precisely consistent with the gravitational radiation energy losses predicted by general relativity.

[3] This work made use of data from the Effelsberg, Arecibo and Green Bank radio telescopes as well as the ESO Very Large Telescope and the William Herschel Telescope optical telescopes.

More information


This research was presented in a paper “A Massive Pulsar in a Compact Relativistic Orbit”, by John Antoniadis et al., to appear in the journal Science on 26 April 2013.


The team is composed of John Antoniadis (Max-Planck-Institut für Radioastronomie [MPIfR], Bonn, Germany), Paulo C. C. Freire (MPIfR), Norbert Wex (MPIfR), Thomas M. Tauris (Argelander Institut für Astronomie, Bonn, Germany; MPIfR), Ryan S. Lynch (McGill University, Montreal, Canada), Marten H. van Kerkwijk (University of Toronto, Canada), Michael Kramer (MPIfR; Jodrell Bank Centre for Astrophysics, The University of Manchester, United Kingdom), Cees Bassa (Jodrell Bank), Vik S. Dhillon (University of Sheffield, United Kingdom), Thomas Driebe (Deutsches Zentrum für Luft- und Raumfahrt, Bonn, Germany), Jason W. T. Hessels (ASTRON, the Netherlands Institute for Radio Astronomy, Dwingeloo, The Netherlands; University of Amsterdam, The Netherlands), Victoria M. Kaspi (McGill University), Vladislav I. Kondratiev (ASTRON; Lebedev Physical Institute, Moscow, Russia), Norbert Langer (Argelander Institut für Astronomie), Thomas R. Marsh (University of Warwick, United Kingdom), Maura A. McLaughlin (West Virginia University), Timothy T. Pennucci (Department of Astronomy, University of Virginia) Scott M. Ransom (National Radio Astronomy Observatory, Charlottesville, USA), Ingrid H. Stairs (University of British Columbia, Vancouver, Canada), Joeri van Leeuwen (ASTRON; University of Amsterdam), Joris P. W. Verbiest (MPIfR), David G. Whelan (Department of Astronomy, University of Virginia).


ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. 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”.

Links



Contacts

John Antoniadis
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Tel: +49-228-525-181
Email:
jantoniadis@mpifr-bonn.mpg.de

Michael Kramer
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Tel: +49-228-525-278
Email:
mkramer@mpifr-bonn.mpg.de

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email:
rhook@eso.org

 

Entire galaxies feel the heat from newborn stars

Artist's impression of a galaxy undergoing a starburst

 Videos

Probing a galactic halo with Hubble
Probing a galactic halo with Hubble

Animation of a starburst galaxy (artist’s impression)
Animation of a starburst galaxy (artist’s impression)


Bursts of star birth can curtail future galaxy growth 

Astronomers using the NASA/ESA Hubble Space Telescope have shown for the first time that bursts of star formation have a major impact far beyond the boundaries of their host galaxy. These energetic events can affect galactic gas at distances of up to twenty times greater than the visible size of the galaxy — altering how the galaxy evolves, and how matter and energy is spread throughout the Universe.

When galaxies form new stars, they sometimes do so in frantic episodes of activity known as starbursts. These events were commonplace in the early Universe, but are rarer in nearby galaxies.

During these bursts, hundreds of millions of stars are born, and their combined effect can drive a powerful wind that travels out of the galaxy. These winds were known to affect their host galaxy — but this new research now shows that they have a significantly greater effect than previously thought.

An international team of astronomers observed 20 nearby galaxies, some of which were known to be undergoing a starburst. They found that the winds accompanying these star formation processes were capable of ionising [1] gas up to 650 000 light-years from the galactic centre — around twenty times further out than the visible size of the galaxy. This is the first direct observational evidence of local starbursts impacting the bulk of the gas around their host galaxy, and has important consequences for how that galaxy continues to evolve and form stars.

The extended material around galaxies is hard to study, as it’s so faint,” says team member Vivienne Wild of the University of St. Andrews. “But it’s important — these envelopes of cool gas hold vital clues about how galaxies grow, process mass and energy, and finally die. We’re exploring a new frontier in galaxy evolution!

The team used the Cosmic Origins Spectrograph (COS) instrument [2] on the NASA/ESA Hubble Space Telescope to analyse light from a mixed sample of starburst and control galaxies. They were able to probe these faint envelopes by exploiting even more distant objects — quasars, the intensely luminous centres of distant galaxies powered by huge black holes. By analysing the light from these quasars after it passed through the foreground galaxies, the team could probe the galaxies themselves.

Hubble is the only observatory that can carry out the observations necessary for a study like this,” says lead author Sanchayeeta Borthakur, of Johns Hopkins University. “We needed a space-based telescope to probe the hot gas, and the only instrument capable of measuring the extended envelopes of galaxies is COS.

The starburst galaxies within the sample were seen to have large amounts of highly ionised gas in their halos — but the galaxies that were not undergoing a starburst did not. The team found that this ionisation was caused by the energetic winds created alongside newly forming stars.

This has consequences for the future of the galaxies hosting the starbursts. Galaxies grow by accreting gas from the space surrounding them, and converting this gas into stars. As these winds ionise the future fuel reservoir of gas in the galaxy’s envelope, the availability of cool gas falls — regulating any future star formation.

Starbursts are important phenomena — they not only dictate the future evolution of a single galaxy, but also influence the cycle of matter and energy in the Universe as a whole,” says team member Timothy Heckman, of Johns Hopkins University. “The envelopes of galaxies are the interface between galaxies and the rest of the Universe — and we’re just beginning to fully explore the processes at work within them.”

The team's results will appear in the 1 May 2013 issue of The Astrophysical Journal.

 

Notes

[1] A gas is said to be ionised when its atoms have lost one or more electrons — in this case by energetic winds exciting galactic gas and knocking electrons out of the atoms within.

[2] Spectrographs are instruments that break light into its constituent colours and measure the intensity of each colour, revealing information about the object emitting the light — such as its chemical composition, temperature, density, or velocity.

 

More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
The research is presented in a paper entitled “The Impact of Starbursts on the Circumgalactic Medium”, published in the 1 May 2013 issue of The Astrophysical Journal.

The international team of astronomers in this study consists of: S. Borthakur (Johns Hopkins University, USA), T. Heckman (Johns Hopkins University, USA), D. Strickland (Johns Hopkins University, USA), V. Wild (University of St. Andrews, UK), D. Schiminovich (Columbia University, USA). 

Image credit: ESA, NASA, L. Calçada

 

Links

 

Contacts

Vivienne Wild
University of St Andrews
UK
Tel: +44 1334 461680
Email:
vw8@st-andrews.ac.uk

Sanchayeeta Borthakur
Johns Hopkins University
Baltimore, Md., USA
Tel: +1 410 516 4737
Email:
sanch@pha.jhu.edu

Nicky Guttridge
Hubble/ESA
Garching, Germany
Tel: +49-89-3200-6855
Email:
nguttrid@partner.eso.org

Wednesday, April 24, 2013

Galaxy Goes Green in Burning Stellar Fuel

The tiny red spot in this image is one of the most efficient star-making galaxies ever observed, converting gas into stars at the maximum possible rate. The galaxy is shown here in an image from NASA's Wide-field Infrared Survey Explorer (WISE), which first spotted the rare galaxy in infrared light. Image credit: NASA/JPL-Caltech/STScI/IRAM. › Full image and caption

Astronomers have spotted the "greenest" of galaxies, one that converts fuel into stars with almost 100-percent efficiency.

The findings come from NASA's Wide-field Infrared Survey Explorer (WISE), NASA's Hubble Space Telescope and the IRAM Plateau de Bure interferometer in the French Alps.

"This galaxy is remarkably efficient," said Jim Geach of McGill University in Canada, lead author of a new study appearing in the Astrophysical Journal Letters. "It's converting its gas supply into new stars at the maximum rate thought possible."

Stars are formed out of collapsing clouds of gas in galaxies. In a typical galaxy, like the Milky Way, only a fraction of the total gas supply is actively forming stars, with the bulk of the fuel lying dormant. The gas is distributed widely throughout the galaxy, with most of the new stars being formed within discrete, dense 'knots' in the spiral arms.

In the galaxy, called SDSSJ1506+54, nearly all of the gas has been driven to the central core of the galaxy, where it has ignited in a powerful burst of star formation.

"We are seeing a rare phase of evolution that is the most extreme -- and most efficient -- yet observed," said Geach.

The results will provide a better understanding of how the central star-forming regions of galaxies take shape.

SDSSJ1506+54 jumped out at the researchers when they looked at it using data from WISE's all-sky infrared survey. Infrared light is pouring out of the galaxy, equivalent to more than a thousand billion times the energy of our sun. The galaxy is so distant it has taken the light nearly six billion years to reach us.

"Because WISE scanned the entire sky, it detected rare galaxies like this one that stand out from the rest," said Ned Wright of UCLA, the WISE principal investigator.

Hubble's visible-light observations revealed that the galaxy is extremely compact, with most of its light emanating from a region just a few hundred light-years across. That's a big star-making punch for such a little size.

"While this galaxy is forming stars at a rate hundreds of times faster than our Milky Way galaxy, the sharp vision of Hubble revealed that the majority of the galaxy's starlight is being emitted by a region with a diameter just a few percent that of the Milky Way," said Geach.

The team then used the IRAM Plateau de Bure Interferometer to measure the amount of gas in the galaxy. The ground-based telescope detected millimeter-wave light coming from carbon monoxide, an indicator of the presence of hydrogen gas, which is fuel for stars. Combining the rate of star formation derived with WISE, and the gas mass measured by IRAM, the scientists get a measure of the star-formation efficiency.

In regions of galaxies where new stars are forming, parts of gas clouds are collapsing due to gravity. When the gas is dense enough to squeeze atoms together and ignite nuclear fusion, a star is born. But this process can be halted by other newborn stars, as their winds and radiation blow the gas outward. The point at which this occurs sets the theoretical maximum for star formation. The galaxy SDSSJ1506+54 was found to be making stars right at this point, just before the gas clouds would otherwise be blown apart.

"We see some gas outflowing from this galaxy at millions of miles per hour, and this gas may have been blown away by the powerful radiation from the newly formed stars," said Ryan Hickox, an astrophysicist at Dartmouth College, Hanover, N.H., and a co-author on the study.

Why is SDSSJ1506+54 so unusual? Astronomers say they're catching the galaxy in a short-lived phase of evolution, possibly triggered by the merging of two galaxies into one. The star formation is so prolific that in a few tens of millions of years, the blink of an eye in a galaxy's life, the gas will be used up, and SDSSJ1506+54 will mature into a massive elliptical galaxy.

The scientists also used data from the Sloan Digital Sky Survey, the W.M. Keck Observatory on Mauna Kea, Hawaii, and the MMT Observatory on Mount Hopkins, Arizona.

For more information about WISE, visit: http://www.nasa.gov/wise . For more information about Hubble, visit: http://www.nasa.gov/hubble


Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


Herschel links Jupiter's water to Comet Impact

Copyright: R. Evans, J. Trauger, H. Hammel and the HST Comet Science Team
Copyright: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University) 

Herschel’s observations found that there was 2–3 times more water in the southern hemisphere of Jupiter than in the northern hemisphere, with most of it concentrated around the sites of the 1994 comet impact. Additionally, it is only found at high altitudes. 

“Only Herschel was able to provide the sensitive spectral imaging needed to find the missing link between Jupiter’s water and the 1994 impact of comet Shoemaker-Levy 9,” says Thibault Cavalié of the Laboratoire d’Astrophysique de Bordeaux, lead author of the paper published in Astronomy and Astrophysics

“According to our models, as much as 95% of the water in the stratosphere is due to the comet impact.” 

Another possible source of water would be a steady rain of small interplanetary dust particles onto Jupiter. But, in this case, the water should be uniformly distributed across the whole planet and should have filtered down to lower altitudes. 

Also, one of Jupiter’s icy moons could deliver water to the planet via a giant vapour torus, as Herschel has seen from Saturn’s moon Enceladus, but this too has been ruled out. None of Jupiter’s large moons is in the right place to deliver water to the locations observed.

Copyright: NASA, ESA, H. Weaver & E. Smith (STScI) and J. Trauger & R. Evans (Jet Propulsion Laboratory)

Finally, the scientists were able to rule out any significant contributions from recent small impacts spotted by amateur astronomers in 2009 and 2010, along with local variations in the temperature of Jupiter’s atmosphere. 

Shoemaker-Levy 9 is the only likely culprit. 

“All four giant planets in the outer Solar System have water in their atmospheres, but there may be four different scenarios for how they got it,” says Dr Cavalié. “For Jupiter, it is clear that Shoemaker-Levy 9 is by far the dominant source, even if other external sources may contribute also.” 

“Thanks to Herschel’s observations, we have now linked a unique comet impact – one that was followed in real time and which captured the public’s imagination – to Jupiter’s water, finally solving a mystery that has been open for nearly two decades,” adds Göran Pilbratt, ESA’s Herschel project scientist. 

The observations made in this study foreshadow those planned for ESA’s future Jupiter Icy moons Explorer mission launching towards the Jovian system in 2022, where it will map the distribution of Jupiter’s atmospheric ingredients in even greater detail. 

Notes for Editors
 
“The spatial distribution of water in the stratosphere of Jupiter from Herschel-HIFI and –PACS observations,” by T. Cavalié et al. is published in Astronomy & Astrophysics, 553, A21, May 2013.
The observations were obtained under the Herschel Guaranteed Time Key Programme “Water and related chemistry in the Solar System”. HIFI observations were taken in July 2010 and PACS observations were made in October 2009 and December 2010.  The results were complemented with data on the stratospheric temperature of Jupiter taken at NASA’s Infrared Telescope Facility taken during the same period.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. 

For further information, please contact:
 
Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email:
markus.bauer@esa.int

Thibault Cavalié
Laboratoire d’Astrophysique de Bordeaux (joint research unit of the CNRS-INSU and University Bordeaux, France)
Tel: +33 5 57 77 61 24
Email:
cavalie@obs.u-bordeaux1.fr

Göran Pilbratt
ESA Herschel Project Scientist
Tel: +31 71 565 3621
Email:
gpilbratt@rssd.esa.int


Tuesday, April 23, 2013

Hubble Captures Comet ISON

 
Comet C/2012 S1 (ISON)
Credit: NASA, ESA, and Z. Levay (STScI),
J.-Y. Li (Planetary Science Institute), 
and the Hubble Comet ISON Imaging Science Team

This NASA Hubble Space Telescope image of Comet C/2012 S1 (ISON) was photographed on April 10, when the comet was slightly closer than Jupiter's orbit at a distance of 386 million miles from the Sun (394 million miles from Earth).

Even at that great distance the comet is already active as sunlight warms the surface and causes frozen volatiles to sublimate. A detailed analysis of the dust coma surrounding the solid, icy nucleus reveals a strong jet blasting dust particles off the sunward-facing side of the comet's nucleus.

Preliminary measurements from the Hubble images suggest that the nucleus of ISON is no larger than three or four miles across. This is remarkably small considering the high level of activity observed in the comet so far, said researchers. Astronomers are using these images to measure the activity level of this comet and constrain the size of the nucleus, in order to predict the comet's activity when it skims 700,000 miles above the Sun's roiling surface on November 28.

The comet's dusty coma, or head of the comet, is approximately 3,100 miles across, or 1.2 times the width of Australia. A dust tail extends more than 57,000 miles, far beyond Hubble's field of view.

More careful analysis is currently underway to improve these measurements and to predict the possible outcome of the sungrazing perihelion passage of this comet.

This image was taken in visible light with Hubble's Wide Field Camera 3. The blue false color was added to bring out details in the comet's structure.

ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences.

For more information, contact:

Ray Villard 

Space Telescope Science Institute, Baltimore, Md. 
410-338-4514
villard@stsci.edu


Three Years of SDO Images

In the three years since it first provided images of the sun in the spring of 2010, NASA’s Solar Dynamics Observatory has had virtually unbroken coverage of the sun's rise toward solar maximum, the peak of solar activity in its regular 11-year cycle. This video shows those three years of the sun at a pace of two images per day.


Credit: NASA's Goddard Space Flight Center
 
SDO’s Atmospheric Imaging Assembly captures a shot of the sun every 12 seconds in 10 different wavelengths. The images shown here are based on a wavelength of 171 angstroms, which is in the extreme ultraviolet range and shows solar material at around 600,000 kelvins (about 1.08 million F). In this wavelength it is easy to see the sun’s 25-day rotation as well as how solar activity has increased over three years.

During the course of the video, the sun subtly increases and decreases in apparent size. This is because the distance between the SDO spacecraft and the sun varies over time. The image is, however, remarkably consistent and stable despite the fact that SDO orbits Earth at 6,876 mph and Earth orbits the sun at 67,062 mph.

This image is a composite of 25 separate images spanning the period of April 16, 2012, to April 15, 2013. It uses the SDO AIA wavelength of 171 angstroms and reveals the zones on the sun where active regions are most common during this part of the solar cycle. Credit: NASA/SDO/AIA/S. Wiessinger.  › Larger image
  
Such stability is crucial for scientists, who use SDO to learn more about our closest star. These images have regularly caught solar flares and coronal mass ejections in the act, types of space weather that can send radiation and solar material toward Earth and interfere with satellites in space. SDO’s glimpses into the violent dance on the sun help scientists understand what causes these giant explosions -- with the hopes of some day improving our ability to predict this space weather. 

Karen C. Fox and Scott Wiessinger
NASA's Goddard Space Flight Center, Greenbelt, Md.



A Dust-Obscured Massive Maximum-Starburst Galaxy in the Early Universe

Astronomers of the Herschel Multi-tiered Extragalactic Survey (HerMES) project announce in the journal Nature the discovery of an unusually massive, maximum-starburst galaxy at a redshift of 6.34, or when the Universe was only 880 million years old. Because current theories of galaxy formation and evolution predict smaller galaxies with slower rates of star production in the early Universe, the detection of such a galaxy is challenging. 
HerMES is the largest project that has being carried out using ESA's Herschel Space Observatory, and other telescopes around the world have made an important contribution,including the William Herschel Telescope (WHT). The extreme galaxy reported here was first detected in the early images obtained using Herschel's SPIRE instrument, the so-called HerMES First Look Survey field (HFLS), showing very unsual red colours in the three bands observed at 250, 350 and 500 microns.

Observations followed using ACAM and LIRIS instruments at the WHT as part of IAC-DDT and ITP programmes (principal investigator: Pérez-Fournon, IAC). These data reveal a faint object close to the position obtained at millimeter interferometric wavelengths. Further analysis from deeper observations using GTC, Keck and Spitzer observatories showed that there are two galaxies appearing very close together.
The field around HFLS3 in the optical (left, GTC OSIRIS), near-IR (top right, WHT LIRIS Ks) and near-IR adaptive optics (bottom right, Keck NIRC2 Ks). In the optical only the foreground G1B galaxy at redshift 2.092 is visible but in the near-IR HFLS3 galaxy at redshift 6.337 is also detected (its rest-frame light lies in UV/optical wavelength range) [ JPEG ]. 
One of these galaxies, or HFLS3, contains 100 billion solar masses of highly-excited, chemically evolved interstellar medium (ISM) which constitutes at least 40% of its baryonic mass. HFLS3 is converting the ISM into stars at 2000 times faster than does our Milky Way galaxy. This is among the highest rates observed at any epoch and thus HFLS3 is a maximum starburst galaxy.

More information



Research reference:

  • D.A. Riechers et al. 2013, "A dust-obscured massive maximum-starburst galaxy at a redshift of 6.34", Nature, 496, 329. Paper.
Web sites:
Press releases:

Contact: Javier Méndez  (Public Relations Officer)



Monday, April 22, 2013

SOFIA Observations Reveal a Surprise in Massive Star Formation

Figures 1a and 1b show the G35 protostar at wavelengths of 31 and 37 microns taken by the FORCAST instrument on the SOFIA observatory's infrared telescope in 2011. (Zhang et al. 2013, Astrophysical Journal) › View Larger Image

WASHINGTON -- Researchers using the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) have captured the most detailed mid-infrared images yet of a massive star condensing within a dense cocoon of dust and gas.

The star is G35.20-0.74, commonly known as G35. It is one of the most massive known protostars and is located relatively close to Earth at a distance of 8,000 light-years.

Until now, scientists expected the formation process of massive stars would be complicated by the turbulent, chaotic environments in the centers of new star clusters where they form. But observations of G35 suggest this giant star, more than 20 times the mass of our sun, is forming by the same orderly process as do stars with the same mass as the sun. Stars most like the sun are understood to form by simple, symmetric collapse of interstellar clouds.

"The focus of our study has been to determine how massive stars actually form," said Yichen Zhang of the University of Florida. Zhang is lead author of a paper about the discovery published April 10 in the Astrophysical Journal. "We thought the G35 protostar's structure would be quite complicated, but instead we found it is simple, like the cocoons of protostars with the sun's mass."

The observations of G35 were made in 2011 with a special camera aboard SOFIA, a modified Boeing 747SP aircraft that can carry a telescope with an effective diameter of 100 inches (2.5 meters) to altitudes as high as 45,000 feet (13,700 meters).

G35 was an ideal target for investigations because it is in an early stage of development. But infrared light coming from G35 is so strong it prevented infrared space telescopes from making detailed images. Also, the protostar is embedded so deeply in its natal cloud that it cannot be detected by optical telescopes observing from the ground at visible wavelengths.

Flying high above the light-blocking water vapor in Earth's atmosphere, the airplane-mounted Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) enabled astronomers to see G35 where it hides -- inside a dark, dense, interstellar dust cloud -- by collecting infrared light escaping the cloud. Uniquely suited for this work, FORCAST detected faint details next to bright structures at wavelengths inaccessible to any other telescope on the ground or in space.

"Massive stars, although rare, are important because there is evidence they foster the formation of smaller stars like our sun, and because at the ends of their lives they create and distribute chemical elements that are the basic building blocks of Earth-like planets," said co-author James De Buizer, a SOFIA staff scientist with the Universities Space Research Association (USRA) at NASA's Ames Research Center in Moffett Field, Calif.

Images of G35 may be viewed on NASA's SOFIA site: http://www.nasa.gov/sofia

Figures 2a (left) and 2b (right) present G35 protostar images obtained by NASA's Spitzer Space Telescope and the Gemini-North telescope at Mauna Kea, Hawaii. (Zhang et al. 2013, Astrophysical Journal) › View Larger Image

Figures 1a and 1b show FORCAST images of G35 at wavelengths of 31 and 37 microns. Figures 2a and 2b respectively present G35 images obtained by NASA's Spitzer Space Telescope and the Gemini-North telescope at Mauna Kea, Hawaii, also used in this study. Figure 3 shows computer model images intended to match characteristics of the central regions of the images in figures 1a and 1b.

The model images show greatly simplified versions of what is revealed especially in the SOFIA images: a luminous protostar heating a dense interstellar cloud from the inside while simultaneously expelling cone-shaped jets of gas toward the tops and bottoms of the frames. The top outflow cone appears brighter because it is directed toward us and there is less obscuring material along the line of sight.

The high resolution of the images showcases the capability of modern infrared detector arrays when used on an airborne platform and gives scientists hope that data gathered in this way substantially will advance their understanding of the Milky Way galaxy.

Figure 3 shows computer model images intended to match characteristics of the central regions of the images of the G35 protostar in figures 1a and 1b. The model images show greatly simplified versions of what is revealed in the images taken by the FORCAST instrument on the SOFIA observatory's infrared telescope: a luminous protostar heating a dense interstellar cloud from the inside while simultaneously expelling cone-shaped jets of gas toward the tops and bottoms of the frames. The top outflow cone appears brighter because it is directed toward us and there is less obscuring material along the line of sight. (Zhang et al. 2013, Astrophysical Journal) › View Larger Image
 
NASA's SOFIA flying observatory lifts off from Air Force Plant 42 in Palmdale, Calif., at sunset on July 15, 2011 to begin an all-night astronomical observation mission. The highly modified Boeing 747SP carries a high-tech 100-inch infrared telescope. (NASA / Carla Thomas) › View Larger Image

FORCAST was built by a team led by Terry Herter of Cornell University in Ithica, N.Y. Co-authors of the Astrophysics Journal paper include scientists from the University of Florida in Gainesville; University of Wisconsin in Madison; University of California at Berkeley; Louisiana State University in Baton Rouge; the Arcetri Observatory in Florence, Italy; and the USRA SOFIA science staff at Ames.

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 USRA headquartered in Columbia, Md., and the German SOFIA Institute at the University of Stuttgart.

For links to USRA and the German SOFIA Institute, visit NASA's SOFIA site and click on "SOFIA Science Center".


J.D. Harrington
Headquarters, Washington
202-358-5241

j.d.harrington@nasa.gov

Nicholas A. Veronico
SOFIA Science Center
Ames Research Center, Moffett Field, Calif.
650-604-4589 / 650-483-6902

nveronico@sofia.usra.edu