Wednesday, April 30, 2014

Length of Exoplanet Day Measured for First Time

Artist’s impression of the planet Beta Pictoris b
 
The universal relation between mass and rotation speed of planets
 
Map of the sky around Beta Pictoris
Around Beta Pictoris

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Videos

Zooming in on Beta Pictoris
Zooming in on Beta Pictoris

VLT measures the spin of Beta Pictoris b

Observations from ESO’s Very Large Telescope (VLT) have, for the first time, determined the rotation rate of an exoplanet. Beta Pictoris b has been found to have a day that lasts only eight hours. This is much quicker than any planet in the Solar System — its equator is moving at almost 100 000 kilometres per hour. This new result extends the relation between mass and rotation seen in the Solar System to exoplanets. Similar techniques will allow astronomers to map exoplanets in detail in the future with the European Extremely Large Telescope (E-ELT).

Exoplanet Beta Pictoris b orbits the naked-eye star Beta Pictoris [1], [2], which lies about 63 light-years from Earth in the southern constellation of Pictor (The Painter’s Easel). This planet was discovered nearly six years ago and was one of the first exoplanets to be directly imaged. It orbits its host star at a distance of only eight times the Earth-Sun distance (eso1024) — making it the closest exoplanet to its star ever to be directly imaged [3].

Using the CRIRES instrument on the VLT, a team of Dutch astronomers from Leiden University and the Netherlands Institute for Space Research (SRON) have now found that the equatorial rotation velocity of exoplanet Beta Pictoris b is almost 100 000 kilometres per hour. By comparison, Jupiter’s equator has a velocity of about 47 000 km per hour [4], while the Earth’s travels at only 1700 km per hour [5]. Beta Pictoris b is more than 16 times larger and 3000 times more massive than the Earth, yet a day on the planet only lasts 8 hours.

It is not known why some planets spin fast and others more slowly,” says co-author Remco de Kok, “but this first measurement of an exoplanet’s rotation shows that the trend seen in the Solar System, where the more massive planets spin faster, also holds true for exoplanets. This must be some universal consequence of the way planets form.

Beta Pictoris b is a very young planet, only about 20 million years old (compared to 4.5 billion years for the Earth) [6]. Over time, the exoplanet is expected to cool and shrink, which will make it spin even faster [7]. On the other hand, other processes might be at play that change the spin of the planet. For instance, the spin of the Earth is slowing down over time due to the tidal interactions with our Moon.

The astronomers made use of a precise technique called high-dispersion spectroscopy to split light into its constituent colours — different wavelengths in the spectrum. The principle of the Doppler effect (or Doppler shift) allowed them to use the change in wavelength to detect that different parts of the planet were moving at different speeds and in opposite directions relative to the observer. By very carefully removing the effects of the much brighter parent star they were able to extract the rotation signal from the planet.

We have measured the wavelengths of radiation emitted by the planet to a precision of one part in a hundred thousand, which makes the measurements sensitive to the Doppler effects that can reveal the velocity of emitting objects,” says lead author Ignas Snellen. “Using this technique we find that different parts of the planet’s surface are moving towards or away from us at different speeds, which can only mean that the planet is rotating around its axis“.

This technique is closely related to Doppler imaging, which has been used for several decades to map the surfaces of stars, and recently that of a brown dwarf [8] — Luhman 16B (eso1404). The fast spin of Beta Pictoris b means that in the future it will be possible to make a global map of the planet, showing possible cloud patterns and large storms.

This technique can be used on a much larger sample of exoplanets with the superb resolution and sensitivity of the E-ELT and an imaging high-dispersion spectrograph. With the planned  Mid-infrared E-ELT Imager and Spectrograph (METIS) we will be able to make global maps of exoplanets and characterise much smaller planets than Beta Pictoris b with this technique”, says METIS principal investigator and co-author of the new paper, Bernhard Brandl.

Notes

[1] Beta Pictoris has many other names, e.g. HD 39060, SAO 234134 and HIP 27321.

[2] Beta Pictoris is one of the best-known examples of a star surrounded by a dusty debris disc. This disc is now known to extend out to about 1000 times the distance between the Earth and the Sun. Earlier observations of Beta Pictoris’s planet were reported in eso0842, eso1024 and eso1408.

[3] The observations made use of the adaptive optics technique compensating for the Earth’s atmospheric turbulence which can distort images obtained at even the best sites in the world for astronomy. It allows astronomers to create super-sharp images, almost as good as those that could be seen from space.

[4] Since Jupiter has no solid surface from which to determine the planet’s rotation rate, we take the rotation speed of its equatorial atmosphere, which is 47 000 km per hour.

[5] The Earth’s rotation speed at the equator is 1674.4 km per hour.

[6] Earlier measurements suggested that the system was younger.

[7] This is a consequence of the conservation of angular momentum and is the same effect that makes a spinning ice skater turn more rapidly when they bring their arms closer to their body.

[8] Brown dwarfs are often dubbed “failed stars” as, unlike stars such as the Sun, they are not massive enough to sustain nuclear fusion reactions.

More information

This research was presented in a paper “Fast spin of a young extrasolar planet”, by I. Snellen et al., to appear in the to appear in the journal Nature on 1 May 2014.

The team is composed of Ignas A. G. Snellen (Leiden Observatory, Leiden University, Leiden, the Netherlands), Bernhard Brandl (Leiden Observatory), Remco J. de Kok (Leiden Observatory, SRON Netherlands Institute for Space Research, Utrecht, the Netherlands), Matteo Brogi (Leiden Observatory), Jayne Birkby (Leiden Observatory) and Henriette Schwarz (Leiden Observatory).


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

Ignas Snellen
Leiden Observatory
Leiden, The Netherlands
Tel: +31 71 52 75 838
Cell: +31 63 00 31 983
Email:
snellen@strw.leidenuniv.nl

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

 Source: ESO 

 

Well-behaved, Young Galaxy Surprises Astronomers

The young galaxy SDSS090122.37+181432.3, also known as S0901, is seen here as the bright arc to the left of the central bright galaxy. Credit: NASA/STScI; S. Allam and team; and the Master Lens Database, L. A. Moustakas, K. Stewart, et al (2014).  Full image and caption

Scientists have discovered a young galaxy acting in unexpectedly mature ways. The galaxy, called S0901, is rotating in a calm manner typical of more developed galaxies like our own spiral Milky Way.

"Usually, when astronomers examine galaxies in an early era, they find that turbulence plays a much greater role than it does in modern galaxies. But S0901 is a clear exception to that pattern," said James Rhoads of Arizona State University, Tempe. 

It has taken the light from the galaxy 10 billion years to reach us across space, so we are seeing it when it was comparatively young. 

"This galaxy is the equivalent of a 10-year-old. I can tell you from watching my kids' classes that 10-year-olds like to fidget! S0901 is unusual because it's not fidgeting, and instead is very well behaved." Rhoads is lead author of the research, appearing in the May 20 issue of the Astrophysical Journal.

The discovery was made using the Herschel space observatory, a European Space Agency mission with important NASA contributions.

"This is a truly surprising result that reminds us that we still don't understand many details of the evolution of the universe. Facilities like Herschel help us understand this complex story," said Paul Goldsmith, U.S. Herschel Project Scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. 

When galaxies form, they accumulate mass because their gravity attracts vast, external gas clouds. As the gas clouds enter a particular galaxy, they fall into haphazard orbits. These disordered paths cause turbulence in the host galaxy, which can drive star formation.

To investigate the internal conditions of forming galaxies, Rhoads and Sangeeta Malhotra, also from Arizona State University, and colleagues targeted two young galaxies, one of them being S0901. 

Using a cosmic magnifier known as a gravitational lens, the researchers got a better view of the galaxies than they would have otherwise. An instrument on Herschel, the Heterodyne Instrument for the Far-Infrared (HIFI), was then able to pick up the signature of ionized carbon, revealing the motion of the gas molecules in the galaxies. This motion was much smoother than anticipated in the S0901 galaxy. Results for the second galaxy hinted at a calm rotation too, but were less clear.

"Galaxies 10 billion years ago were making stars more actively than they do now," says Malhotra. "They usually also show more turbulence, likely because they are accumulating gas faster than a modern galaxy does. But here we have cases where an early galaxy combines the calm rotation of a modern one with the active star formation of their early peers."

More observations with other telescopes should help reveal if other galaxies behave in similarly grown-up ways, or if S0901 is oddly ahead of its time.

 
Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA's Herschel Project Office is based at JPL. JPL contributed mission-enabling technology for two of Herschel's three science instruments, including HIFI. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community. Caltech manages JPL for NASA. 

More information is online at these websites:

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

whitney.clavin@jpl.nasa.gov

Tuesday, April 29, 2014

Glowing jewels in the Galactic Plane

Copyright: ESA/PACS & SPIRE Consortium, S. Molinari, Hi-GAL Project
    The majority of the stars in our Galaxy, the Milky Way, reside in a single huge disc, known as the Galactic Plane, spanning 100 000 light-years across. The Sun also resides in this crowded stellar hub, lying roughly halfway between its centre and its outer edges.

    This disc is filled with a diffuse mixture of gas and dust – the interstellar medium – that pervades space, filling the large gaps found between stars. Occasionally, these clouds of gas and dust cool, becoming denser and denser until they spark star formation, giving rise to new generations of stars.

    This image is part of Hi-GAL, a survey of the Galactic Plane completed with ESA’s Herschel Space Observatory. Peering at the sky in infrared light, Herschel could detect the glow of dust particles dispersed between stars. This minor – but crucial – component of the interstellar medium allows astronomers to investigate how stars are born in the Milky Way, and how they affect their environment as they age.

    Nestled in the Milky Way’s disc are pockets of gas and dust that have been heated by nearby newborn stars, causing them to glow brightly like cosmic gems. Through their higher temperatures, these regions glow at shorter infrared wavelengths and are depicted in violet and green, while the colder material in the surroundings – only a few tens of degrees above absolute zero – appears redder.

    Laced amongst the stars is an intricate network of filaments sprinkled with tiny white spots: these are denser clumps of gas and dust that will likely evolve and give birth to new stars.

    The image combines observations from the PACS and SPIRE instruments on Herschel. It spans about 12º on the longer side, corresponding to some 24 times the diameter of the full Moon. This is 1/30th of the entire Galactic Plane survey.

    This image was first published in OSHI, the Online Showcase of Herschel Images, in 2011. 

Monday, April 28, 2014

NASA's Spitzer, WISE Find Sun's Close, Cold Neighbor

This artist's conception shows the object named WISE J085510.83-071442.5, the coldest known brown dwarf. Brown dwarfs are dim star-like bodies that lack the mass to burn nuclear fuel as stars do.  Full image and caption

This animation shows the coldest brown dwarf yet seen, and the fourth closest system to our sun. Called WISE J085510.83-071442.5, this dim object was discovered through its rapid motion across the sky.  Full image and caption - enlarge image

This diagram illustrates the locations of the star systems closest to the sun. The year when the distance to each system was determined is listed after the system's name.  Full image and caption  -  enlarge image

NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope have discovered what appears to be the coldest "brown dwarf" known -- a dim, star-like body that surprisingly is as frosty as Earth's North Pole. 

Images from the space telescopes also pinpointed the object's distance to 7.2 light-years away, earning it the title for fourth closest system to our sun. The closest system, a trio of stars, is Alpha Centauri, at about 4 light-years away. 

"It's very exciting to discover a new neighbor of our solar system that is so close," said Kevin Luhman, an astronomer at Pennsylvania State University's Center for Exoplanets and Habitable Worlds, University Park. "And given its extreme temperature, it should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."

Brown dwarfs start their lives like stars, as collapsing balls of gas, but they lack the mass to burn nuclear fuel and radiate starlight. The newfound coldest brown dwarf is named WISE J085510.83-071442.5. It has a chilly temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13 degrees Celsius). Previous record holders for coldest brown dwarfs, also found by WISE and Spitzer, were about room temperature.

WISE was able to spot the rare object because it surveyed the entire sky twice in infrared light, observing some areas up to three times. Cool objects like brown dwarfs can be invisible when viewed by visible-light telescopes, but their thermal glow -- even if feeble -- stands out in infrared light. In addition, the closer a body, the more it appears to move in images taken months apart. Airplanes are a good example of this effect: a closer, low-flying plane will appear to fly overhead more rapidly than a high-flying one. 

"This object appeared to move really fast in the WISE data," said Luhman. "That told us it was something special."

After noticing the fast motion of WISE J085510.83-071442.5 in March of 2013, Luhman spent time analyzing additional images taken with Spitzer and the Gemini South telescope on Cerro Pachon in Chile. Spitzer's infrared observations helped determine the frosty temperature of the brown dwarf. Combined detections from WISE and Spitzer, taken from different positions around the sun, enabled the measurement of its distance through the parallax effect. This is the same principle that explains why your finger, when held out right in front of you, appears to jump from side to side when you alternate left- and right-eye views.

"It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the sun's nearest neighbors," said Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif. JPL manages and operates Spitzer. "This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer."

WISE J085510.83-071442.5 is estimated to be 3 to 10 times the mass of Jupiter. With such a low mass, it could be a gas giant similar to Jupiter that was ejected from its star system. But scientists estimate it is probably a brown dwarf rather than a planet since brown dwarfs are known to be fairly common. If so, it is one of the least massive brown dwarfs known.

In March of 2013, Luhman's analysis of the images from WISE uncovered a pair of much warmer brown dwarfs at a distance of 6.5 light years, making that system the third closest to the sun. His search for rapidly moving bodies also demonstrated that the outer solar system probably does not contain a large, undiscovered planet, which has been referred to as "Planet X" or "Nemesis." 

For more information on NASA's WISE mission, visit: http://www.nasa.gov/wise

For more information on NASA's Spitzer mission, visit: http://www.nasa.gov/spitzer

The California Institute of Technology in Pasadena manages JPL for NASA.

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

whitney.clavin@jpl.nasa.gov

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

j.d.harrington@nasa.gov



Friday, April 25, 2014

Astro Pro-Am: Professional and Amateur Astronomers Join Forces

Optical (M101, M81, M51): Detlef Hartmann; 
Optical (Centaurus A): Rolf Olsen; 
Infrared: NASA/JPL-Caltech


Pro-Am Tour

animation

Long before the term "citizen science" was coined, the field of astronomy has benefited from countless men and women who study the sky in their spare time. These amateur astronomers devote hours exploring the cosmos through a variety of telescopes that they acquire, maintain, and improve on their own. Some of these amateur astronomers specialize in capturing what is seen through their telescopes in images and are astrophotographers.
What happens when the work of amateur astronomers and astrophotographers is combined with the data from some of the world's most sophisticated space telescopes? Collaborations between professional and amateur astronomers reveal the possibilities and are intended to raise interest and awareness among the community of the wealth of data publicly available in NASA's various mission archives. This effort is particularly appropriate for this month because April marks Global Astronomy Month, the world's largest global celebration of astronomy.

The images in this quartet of galaxies represent a sample of composites created with X-ray data from NASA's Chandra X-ray Observatory, infrared data from the Spitzer Space Telescope, and optical data collected by an amateur astronomer. In these images, the X-rays from Chandra are shown in purple, infrared emission from Spitzer is red, and the optical data are in red, green, and blue. The two astrophotographers who donated their images for these four images -- Detlef Hartmann and Rolf Olsen -- used their personal telescopes of 17.5 inches and 10 inches in diameter respectively. More details on how these images were made can be found in this blog post.

Starting in the upper left and moving clockwise, the galaxies are M101 (the "Pinwheel Galaxy"), M81, Centaurus A, and M51 (the "Whirlpool Galaxy"). M101 is a spiral galaxy like our Milky Way, but about 70% bigger. It is located about 21 million light years from Earth. M81 is a spiral galaxy about 12 million light years away that is both relatively large in the sky and bright, making it a frequent target for both amateur and professional astronomers. Centaurus A is the fifth brightest galaxy in the sky -- making it an ideal target for amateur astronomers -- and is famous for the dust lane across its middle and a giant jet blasting away from the supermassive black hole at its center. Finally, M51 is another spiral galaxy, about 30 million light years away, that is in the process of merging with a smaller galaxy seen to its upper left.

For many amateur astronomers and astrophotographers, a main goal of their efforts is to observe and share the wonders of the Universe. However, the long exposures of these objects may help to reveal phenomena that may otherwise be missed in the relatively short snapshots taken by major telescopes, which are tightly scheduled and often oversubscribed by professional astronomers. Therefore, projects like this Astro Pro-Am collaboration might prove useful not only for producing spectacular images, but also contributing to the knowledge of what is happening in each of these cosmic vistas.

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 in Cambridge, Mass., controls Chandra's science and flight operations.





Cosmic fairy lights

Credit: ESA/Hubble & NASA
 
This sparkling jumble is Messier 5 — a globular cluster consisting of hundreds of thousands of stars bound together by their collective gravity.

But Messier 5 is no normal globular cluster. At 13 billion years old it is incredibly old, dating back to close to the beginning of the Universe, which is some 13.8 billion years of age. It is also one of the biggest clusters known, and at only 24 500 light-years away, it is no wonder that Messier 5 is a popular site for astronomers to train their telescopes on.

Messier 5 also presents a puzzle. Stars in globular clusters grow old and wise together. So Messier 5 should, by now, consist of old, low-mass red giants and other ancient stars. But it is actually teeming with young blue stars known as blue stragglers. These incongruous stars spring to life when stars collide, or rip material from one another.



Thursday, April 24, 2014

Astronomical Forensics Uncover Planetary Disks in Hubble Archive

Circumstellar Disks HD 141943 and HD 191089
Image Credit: NASA, ESA, and R. Soummer and A. Feild (STScI).  Science Credit: NASA, ESA, R. Soummer (STScI), and M. Perrin (STScI), L. Pueyo (STScI/Johns Hopkins University), C. Chen and D. Golimowski (STScI), J.B. Hagan (STScI/Purdue University), T. Mittal (University of California, Berkeley/Johns Hopkins University), E . Choquet, M. Moerchen, and M. N’Diaye (STScI), A. Rajan (Arizona State University), S. Wolff (STScI/Purdue University), J. Debes and D. Hines (STScI), and G. Schneider (Steward Observatory/University of Arizona). Release images

With the Hubble Space Telescope, if astronomers missed seeing something once in their data, they haven't missed it forever. Thanks to the wealth of information stored in the Hubble data archive, and given enough time to come up with more clever ways of scientific analysis, they can revisit existing observations and make new discoveries not caught initially.

Such is the case with four disks of planetary debris uncovered in images of young stars that astronomers retrieved from the Barbara A. Mikulski Archive for Space Telescopes (MAST). A fifth disk image, which was an unpublished borderline detection by Hubble from 2007, was also recovered. These disks are telltale evidence for newly formed planets.

This is an astronomical forensics story of revisiting earlier data with new image processing techniques — and of some tenacious astronomers. Rémi Soummer, of the Space Telescope Science Institute (STScI) in Baltimore, Md., led the team on an Indiana Jones hunt for hidden Hubble treasures.

The stars were initially targeted with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) based on unusual heat signatures obtained from NASA space-based telescopes, including IRAS (Infrared Astronomical Satellite) and the Spitzer Space Telescope. The previous data provided interesting clues that dusty disks might exist around these stars. Such disks might be seen in scattered light from small dust particles. But when Hubble first viewed the stars between 1999 and 2006, no visible-light disks were detected in the NICMOS pictures.

Recently, with improvements in image processing — including algorithms used for face-recognition software — Soummer and his team reanalyzed the archived images. This time, they could unequivocally see the debris disks, and they could even determine their shapes.

"These findings increase the number of debris disks seen in scattered light from 18 to 23. By significantly adding to the known population, and by showing the variety of shapes in these new disks, Hubble can help astronomers learn more about how planetary systems form and evolve," said Soummer.

The dust in the disks is hypothesized to be produced by collisions between small planetary bodies such as asteroids. The debris disks are composed of dust particles formed from these grinding collisions. The tiniest particles are constantly blown outward by radiation pressure from the star. This means they must be replenished continuously though more collisions. This game of bumper cars was common in the solar system 4.5 billion years ago. Earth's moon and the satellite system around Pluto are considered to be collisional byproducts.

"One star that is particularly interesting is HD 141943," said Christine Chen, debris disk expert and team member. "It is an exact twin of our Sun during the epoch of terrestrial planet formation in our own solar system." Hubble found that the star exhibits an asymmetrical, edge-on disk. This asymmetry could be evidence the disk is being gravitationally sculpted by the tug of one or more unseen planets.

The NICMOS instrument, which began taking data in 1997, was so cutting-edge that ground-based technology is only now beginning to match its power. Because Hubble has been in operation for 24 years, it provides a long baseline of high-quality archival observations. "Now, with such new technologies in image processing, we can go back to the archive and conduct research more precisely than previously possible with NICMOS data," said Dean Hines of STScI.

Once Soummer's team began to apply the new algorithm to the old data, the disks immediately started appearing. "I remember we tried it, and we thought, 'It's not possible. We've done something wrong!' The disks popped out immediately," explained Soummer. "It worked so well, and the results came up so quickly, that at first we didn't believe them."

"Being able to see these disks now also has let us plan further observations to study them in even more detail using other Hubble instruments and large telescopes on the ground," added Marshall Perrin of STScI.
"We are also working to implement the same techniques as a standard processing method for the upcoming James Webb Space Telescope," said STScI teammate Laurent Pueyo. "These disks will also be prime targets for the Webb Telescope."
Soummer's team has just begun its work. They will next search for structures in the disks that suggest the presence of planets.
The Space Telescope Science Institute in Baltimore, Md., conducts Hubble Space Telescope (HST) science operations. HST 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. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
The Mikulski Archive for Space Telescopes, located at STScI, is a NASA-funded project to support and provide to the astronomical community a variety of astronomical data archives, with the primary focus on scientifically related data sets in the optical, ultraviolet, and near-infrared parts of the spectrum.

CONTACT:

Ann Jenkins / Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4488 / 410-338-4514

jenkins@stsci.edu / villard@stsci.edu

Rémi Soummer
Space Telescope Science Institute, Baltimore, Md.
410-338-4737

soummer@stsci.edu


Source: Hubble Site


Wednesday, April 23, 2014

An X-ray view of the COSMOS field

An X-ray view of the COSMOS field
Copyright: ESA/XMM-Newton/Gunther Hasinger, Nico Cappelluti, and the XMM-COSMOS collaboration.
 
When we gaze up at the night sky, we are only seeing part of the story. Unfortunately, some of the most powerful and energetic events in the Universe are invisible to our eyes – and to even the best optical telescopes.

Luckily, these events are not lost; they appear vividly in the high-energy sky, making them visible to space-based telescopes like ESA's XMM-Newton, which observes the Universe in the X-ray part of the spectrum.

This image shows a patch of sky from the COSMOS survey, as viewed by XMM-Newton. COSMOS is a project studying how galaxies form and evolve, gathering observations using a variety of ground- and space-based telescopes. This image alone features about two thousand supermassive black holes, and over a hundred clusters of galaxies.

Small point sources dotted across the frame show supermassive black holes that are hungrily devouring matter from their surroundings. All massive galaxies host a black hole at their core, but not all of these are actively accreting, dragging in surrounding matter and releasing high-energy radiation and powerful jets in the process. As they are so energetic, one of the best ways to hunt these extreme bodies is by using X-ray telescopes.

The larger blobs in this image, mainly red and yellow, reveal another class of cosmic behemoths: galaxy clusters. Containing up to several thousand galaxies, galaxy clusters are the largest cosmic structures to be held together by gravity. The galaxies within these clusters are enveloped by hot gas, which releases a diffuse X-ray glow that can be detected by telescopes like XMM-Newton.

The image combines data collected by the EPIC instrument on board XMM-Newton at energies from 0.5 to 2 keV (shown in red), 2 to 4.5 keV (shown in green) and 4.5 to 10 keV (shown in blue). The observations were taken between 2003 and 2005, and the image spans 1.4 degrees on each side, corresponding to almost three times the diameter of the full Moon.

This image was first published in the paper “The XMM-Newton Wide-Field Survey in the COSMOS Field. I. Survey Description” by G. Hasinger et al. in 2007.


Source: ESA


Tuesday, April 22, 2014

A Dance of Black Holes


Unique pair of supermassive black holes in an ordinary galaxy discovered by XMM-Newton

A pair of supermassive black holes in orbit around one another have been discovered by an international research team including Stefanie Komossa from the Max Planck Institute for Radio Astronomy in Bonn, Germany. This is the first time such a pair could be found in an ordinary galaxy. They were discovered because they ripped apart a star when ESA’s space observatory XMM-Newton happened to be looking in their direction.

The findings are published in the May 10 issue of the “Astrophysical Journal”, and appeared online today at the astrophysics preprint server.

Most massive galaxies in the Universe are thought to harbour at least one supermassive black hole at their centre. Two supermassive black holes are the smoking gun that the galaxy has merged with another. Thus, finding binary supermassive black holes can tell astronomers about how galaxies evolved into their present-day shapes and sizes.

To date, only a few candidates for close binary supermassive black holes have been found. All are in active galaxies where they are constantly ripping gas clouds apart, in the prelude to crushing them out of existence.

In the process of destruction, the gas is heated so much that it shines at many wavelengths, including X-rays. This gives the galaxy an unusually bright centre, and leads to it being called active. The new discovery, reported by Fukun Liu from Peking University in China, and colleagues, is important because it is the first to be found in a galaxy that is not active.

“There might be a whole population of quiescent galaxies that host binary black holes in their centres,” says co-author Stefanie Komossa, Max-Planck-Institut für Radioastronomie, Bonn, Germany. But finding them is a difficult task because in quiescent galaxies, there are no gas clouds feeding the black holes, and so the cores of these galaxies are truly dark.

The only hope that the astronomers have is to be looking in the right direction at the moment one of the black holes goes to work, and rips a star to pieces. Such an occurrence is called a ‘tidal disruption event’. As the star is pulled apart by the gravity of the black hole, it gives out a flare of X-rays.

In an active galaxy, the black hole is continuously fed by gas clouds. In a quiescent galaxy, the black hole is fed by tidal disruption events that occur sporadically and are impossible to predict. So, to increase the chances of catching such an event, researchers use ESA’s X-ray observatory, XMM-Newton, in a novel way.

Usually, the observatory collects data from designated targets, one at a time. Once it completes an observation, it slews to the next. The trick is that during this movement, XMM-Newton keeps the instruments turned on and recording. Effectively this surveys the sky in a random pattern, producing data that can be analysed for unknown or unexpected sources of X-rays.

On 10 June 2010, a tidal disruption event was spotted by XMM-Newton in galaxy SDSS J120136.02+300305.5, approximately 2 billion light years away.  Komossa and her colleagues were scanning the data for such events and scheduled follow-up observations just days later with XMM-Newton and NASA’s Swift satellite.

The galaxy was still spilling X-rays into space. It looked exactly like a tidal disruption event caused by a supermassive black hole but as they tracked the slowly fading emission day after day something strange happened.

The X-rays fell below detectable levels between days 27 and 48 after the discovery. Then they re-appeared and continued to follow a more expected fading rate, as if nothing had happened.

Now, thanks to Fukun Liu, this behaviour can be explained. “This is exactly what you would expect from a pair of supermassive black holes orbiting one another,” says Liu.

Liu had been working on models of black hole binary systems that predicted a sudden plunge to darkness and then the recovery because the gravity of one of the black holes disrupted the flow of gas onto the other, temporarily depriving it of fuel to fire the X-ray flare. He found that two possible configurations were possible to reproduce the observations of J120136.

In the first, the primary black hole contained 10 million solar masses and was orbited by a black hole of about a million solar masses in an elliptical orbit. In the second solution, the primary black hole was about a million solar masses in a circular orbit.

In both cases, the separation between the black holes was relatively small: 0.6 milliparsecs, or about 2 thousandths of a light year. This is about the width of our Solar System.

Being this close, the fate of this newly discovered black hole pair is sealed. They will radiate their orbital energy away, gradually spiralling together, until in about two million years time they will merge into a single black hole.

Now that astronomers have found this first candidate for a binary black hole in a quiescent galaxy, the search is inevitably on for more. XMM-Newton will continue its slew survey. This detection will also spur interest in a network of telescopes that search the whole sky for tidal disruption events.

“Once we have detected thousands of tidal disruption events, we can begin to extract reliable statistics about the rate at which galaxies merge,” says Stefanie Komossa.

When binary black holes merge, they are predicted to release a massive burst of energy into the Universe but not mostly in X-rays. “The final merger is expected to be the strongest source of gravitational waves in the Universe,” states Fukun Liu.

 “The innovative use of XMM-Newton’s slew observations made the detection of this binary supermassive black hole system possible,” concludes Norbert Schartel, ESA's XMM-Newton Project Scientist. “This demonstrates the important role that long-lasting space observatories have in detecting such rare events that can potentially open new areas in astronomy.” 

Background Information:

Original Paper:


F.K. Liu, Shuo Li, and S. Komossa, published in: 2014, Astrophysical Journal, Volume 786, Article 103 (May 10). DOI:10.1088/0004-637X/786/2/103. arXiv:1404.4933 [astro-ph.HE]


Contatcs: 

Dr. Stefanie Komossa
Phone:+49 228 525-431
Max-Planck-Institut für Radioastronomie, Bonn

Dr. Norbert Schartel
ESA XMM-Newton Projektwissenschaftler
Phone:+34 91 8131-184
Europäische Raumfahrtagentur (ESA)

Dr. Norbert Junkes Presse- und Öffentlichkeitsarbeit
Phone:+49 228 525-399
Max-Planck-Institut für Radioastronomie, Bonn




A New Map of the Galaxy in the Light of Atomic Hydrogen

A new image of the Lagoon Nebula as seen with the VPHAS+ survey in the light of atomic hydrogen. The survey has just begun to return science results; there are roughly 300 million objects in its catalog. (Video link)


Atomic hydrogen is the lightest and by far most abundant element in the universe. When it is exposed to ultraviolet light, its single electron can be stripped from the atom, a situation that arises near stars that are hot. When a free electron then reunites with a proton to form a neutral atom it emits light including the visible H-alpha emission line. A region of H-alpha emission - a nebula - thus signals the presence of ionized gas near a hot star.

Typically stars are hot either because they are young and massive or because their nuclear burning has progressed to a hotter phase; they include O-stars, Be stars, supergiants, luminous blue variable stars, Wolf-Rayet stars, as well as very young stars of all masses and compact interacting binary stars. Surveys that take images in H-alpha emission are thus excellent detectors of hot stars and associated phenomena, not least because nebulae are comparatively larger in size and easier to spot than are the point-like stars that heat them.

In the southern hemisphere, the last time anyone published a systematic survey of H-alpha light was in 1971, and that study has been a standard astronomical resource ever since. But no longer. CfA astronomer Jeremy Drake has joined a large team of colleagues to make a new H-alpha study of the southern galactic plane, called VPHAS+ (the VST Photometric H-alpha Survey), with the plus indicating that four optical wavelengths are also surveyed in addition to the H-alpha wavelength.

The VPHAS+ catalog, which is soon to be completed, will have about 300 million stars, and will include stars and nebulae that are as much as 1500 times fainter than the ones in the older catalog, as well as much improved images of all objects. Because dust obscures optical light, the new survey will also be able to spot objects that previously were too obscured for detection. The first set of papers using this new catalog have started to appear, and as the data pipeline and calibration progresses the community expects this catalog to become a standard reference and a tool for exploration of the ultraviolet Milky Way.

Reference(s): 
"The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+)," J. E. Drew et al., MNRAS 440, 2036, 2014.

Monday, April 21, 2014

Sun Emits a Mid-level Solar Flare

The sun emitted a mid-level solar flare, peaking at 9:03 a.m. EDT on April 18, 2014, and NASA's Solar Dynamics Observatory captured images of the event. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

A mid-level flare burst from the sun on April 18, 2014, as seen as a bright spot in the center of this image. The image was captured by NASA's Solar Dynamics Observatory in 304 angstrom.Image Credit: NASA/SDO. View a full disk image in 131 angstrom

To see how this event may impact Earth, please visit NOAA's Space Weather Prediction Center at http://spaceweather.gov, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

This flare is classified as an M7-class flare. M-class flares are one step below the most intense flares, which are designated as X-class.

Updates will be provided as needed.

Related Links
Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.



Friday, April 18, 2014

Galaxies spiralling around Leo

Credit: ESA/Hubble & NASA
Acknowledgement: Nick Rose
 
Shown here is a spiral galaxy known as NGC 3455, which lies some 65 million light-years away from us in the constellation of Leo (The Lion).

Galaxies are classified into different types according to their structure and appearance. This classification system is known as the Hubble Sequence, named after its creator Edwin Hubble.

In this sequence, NGC 3455 is known as a type SB galaxy — a barred spiral. Barred spiral galaxies account for approximately two thirds of all spirals. Galaxies of this type appear to have a bar of stars slicing through the bulge of stars at their centre. The SB classification is further sub-divided by the appearance of a galaxy's pinwheeling spiral arms; SBa types have more tightly wound arms, whereas SBc types have looser ones. SBb types, such as NGC 3455, lie in between.

NGC 3455 is part of a pair of galaxies — its partner, NGC 3454, lies out of frame. This cosmic duo belong to a group known as the NGC 3370 group, which is in turn one of the Leo II groups, a large collection of galaxies scattered some 30 million light-years to the right of the Virgo cluster.

This new image is from Hubble's Advanced Camera for Surveys (ACS). A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Nick Rose.


Source: ESA/Hubble  - Space Telescope

NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star

The artist's concept depicts Kepler-186f , the first validated Earth-size planet to orbit a distant star in the habitable zone. Image Credit: NASA Ames/SETI Institute/JPL-Caltech. Kepler-186f, the first Earth-size Planet in the Habitable Zone
 
The diagram compares the planets of our inner solar system to Kepler-186, a five-planet star system about 500 light-years from Earth in the constellation Cygnus. The five planets of Kepler-186 orbit an M dwarf, a star that is is half the size and mass of the sun. Image Credit: NASA Ames/SETI Institute/JPL-Caltech. Kepler-186 and the Solar System
 
Using NASA's Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the "habitable zone" -- the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.

While planets have previously been found in the habitable zone, they are all at least 40 percent larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth.

"The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth," said Paul Hertz, NASA's Astrophysics Division director at the agency's headquarters in Washington. "Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds."

Although the size of Kepler-186f is known, its mass and composition are not. Previous research, however, suggests that a planet the size of Kepler-186f is likely to be rocky.

"We know of just one planet where life exists -- Earth. When we search for life outside our solar system we focus on finding planets with characteristics that mimic that of Earth," said Elisa Quintana, research scientist at the SETI Institute at NASA's Ames Research Center in Moffett Field, Calif., and lead author of the paper published today in the journal Science. "Finding a habitable zone planet comparable to Earth in size is a major step forward."

Kepler-186f resides in the Kepler-186 system, about 500 light-years from Earth in the constellation Cygnus. The system is also home to four companion planets, which orbit a star half the size and mass of our sun. The star is classified as an M dwarf, or red dwarf, a class of stars that makes up 70 percent of the stars in the Milky Way galaxy.

"M dwarfs are the most numerous stars," said Quintana. "The first signs of other life in the galaxy may well come from planets orbiting an M dwarf."

Kepler-186f orbits its star once every 130-days and receives one-third the energy from its star that Earth gets from the sun, placing it nearer the outer edge of the habitable zone. On the surface of Kepler-186f, the brightness of its star at high noon is only as bright as our sun appears to us about an hour before sunset.
"Being in the habitable zone does not mean we know this planet is habitable. The temperature on the planet is strongly dependent on what kind of atmosphere the planet has," said Thomas Barclay, research scientist at the Bay Area Environmental Research Institute at Ames, and co-author of the paper. "Kepler-186f can be thought of as an Earth-cousin rather than an Earth-twin. It has many properties that resemble Earth."

The four companion planets, Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e, whiz around their sun every four, seven, 13, and 22 days, respectively, making them too hot for life as we know it. These four inner planets all measure less than 1.5 times the size of Earth.

The next steps in the search for distant life include looking for true Earth-twins -- Earth-size planets orbiting within the habitable zone of a sun-like star -- and measuring the their chemical compositions. The Kepler Space Telescope, which simultaneously and continuously measured the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun.

Ames is responsible for Kepler's ground system development, mission operations, and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate.

The SETI Institute is a private, nonprofit organization dedicated to scientific research, education and public outreach.  The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe.

For more information about the Kepler mission, visit: http://www.nasa.gov/kepler



Media contacts:

Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-6982

michele.johnson@nasa.gov

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

j.d.harrington@nasa.gov

Thursday, April 17, 2014

A cross-section of the Universe

Hubble’s cross-section of the cosmos

Annotated image of the field around CLASS B1608+656

Digitized Sky Survey Image around CLASS B1608+656 
(ground-based image)

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Videos

Zoom in on CLASS B1608+656
Zoom in on CLASS B1608+656

Pan across CLASS B1608+656
Pan across CLASS B1608+656


An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range from cosmic near neighbours to objects seen in the early years of the Universe. The 14-hour exposure shows objects around a billion times fainter than can be seen with the naked eye.

This new Hubble image showcases a remarkable variety of objects at different distances from us, extending back over halfway to the edge of the observable Universe. The galaxies in this image mostly lie about five billion light-years from Earth but the field also contains other objects, both significantly closer and far more distant.

Studies of this region of the sky have shown that many of the objects that appear to lie close together may actually be billions of light-years apart. This is because several groups of galaxies lie along our line of sight, creating something of an optical illusion. Hubble’s cross-section of the Universe is completed by distorted images of galaxies in the very distant background.

These objects are sometimes distorted due to a process called gravitational lensing, an extremely valuable technique in astronomy for studying very distant objects [1]. This lensing is caused by the bending of the space-time continuum by massive galaxies lying close to our line of sight to distant objects.

One of the lens systems visible here is called CLASS B1608+656, which appears as a small loop in the centre of the image. It features two foreground galaxies distorting and amplifying the light of a distant quasar the known as QSO-160913+653228. The light from this bright disc of matter, which is currently falling into a black hole, has taken nine billion years to reach us — two thirds of the age of the Universe.

As well as CLASS B1608+656, astronomers have identified two other gravitational lenses within this image. Two galaxies, dubbed Fred and Ginger by the researchers who studied them, contain enough mass to visibly distort the light from objects behind them. Fred, also known more prosaically as [FMK2006] ACS J160919+6532, lies near the lens galaxies in CLASS B1608+656, while Ginger ([FMK2006] ACS J160910+6532) is markedly closer to us. Despite their different distances from us, both can be seen near to CLASS B1608+656 in the central region of this Hubble image.

To capture distant and dim objects like these, Hubble required a long exposure. The image is made up of visible and infrared observations with a total exposure time of 14 hours.

Notes

[1] Gravitational lensing can amplify the light coming from distant objects, enabling telescopes like Hubble to see objects that would otherwise be too faint and far away. This effect will be exploited during the Frontier Fields observing campaign in the near future, which aims to combine the power of Hubble with the natural amplification caused by strong gravitational lensing of distant galaxy clusters, to study the past Universe.

More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.


The image was spotted by contestant Adam Kill in the 2012 Hubble's Hidden Treasures competition. Hidden Treasures invited members of the public to search Hubble's science for the best overlooked images that have never been seen by a general audience. This image of CLASS B1608+656 has been well-studied by scientists over the years, but this is the first time it has been published in full online.

Links


Contacts

Georgia Bladon
Hubble/ESA
Garching, Germany
Tel: +49-89-3200-6855
Email:
gbladon@partner.eso.org



Wednesday, April 16, 2014

A Study in Scarlet

The star formation region Gum 41
The star formation region Gum 41 in the constellation of Centaurus

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Videos

Zooming in on the star formation region Gum 41
Zooming in on the star formation region Gum 41

Panning across the star formation region Gum 41
Panning across the star formation region Gum 41

This new image from ESO’s La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that causes the surrounding hydrogen to glow with a characteristic red hue.

This area of the southern sky, in the constellation of Centaurus (The Centaur), is home to many bright nebulae, each associated with hot newborn stars that formed out of the clouds of hydrogen gas. The intense radiation from the stellar newborns excites the remaining hydrogen around them, making the gas glow in the distinctive shade of red typical of star-forming regions. Another famous example of this phenomenon is the Lagoon Nebula (eso0936), a vast cloud that glows in similar bright shades of scarlet.

The nebula in this picture is located some 7300 light-years from Earth. Australian astronomer Colin Gum discovered it on photographs taken at the Mount Stromlo Observatory near Canberra, and included it in his catalogue of 84 emission nebulae, published in 1955. Gum 41 is actually one small part of a bigger structure called the Lambda Centauri Nebula, also known by the more exotic name of the Running Chicken Nebula (another part of which was the topic of eso1135). Gum died at a tragically early age in a skiing accident in Switzerland in 1960.

In this picture of Gum 41, the clouds appear to be quite thick and bright, but this is actually misleading. If a hypothetical human space traveller could pass through this nebula, it is likely that they would not notice it as — even at close quarters — it would be too faint for the human eye to see. This helps to explain why this large object had to wait until the mid-twentieth century to be discovered — its light is spread very thinly and the red glow cannot be well seen visually.

This new portrait of Gum 41 — likely one of the best so far of this elusive object — has been created using data from the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. It is a combination of images taken through blue, green, and red filters, along with an image using a special filter designed to pick out the red glow from hydrogen.

More information

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

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