Thursday, June 30, 2016

It’s not easy being green – what colours tell us about galaxy evolution

Composite image of blue, green and red galaxies: L-R Virtual images of blue, green and red galaxies produced by the EAGLE simulations. The green galaxy is caught in the act of transforming from blue to red as its gas supply runs out. Credit: James Trayford/EAGLE/Durham University. Click for a full size image


Scientists may have answered why green galaxies are rare in our universe and why their colour could reveal a troubled past. Their research is presented today (Thursday 30 June) at the National Astronomy Meeting at the University of Nottingham.

The international team, led from Durham University's Institute for Computational Cosmology (ICC), used new computer modelling of the universe to investigate the colours that galaxies have and what those colours might tell us about how galaxies evolve. Using the state of the art EAGLE simulations, the researchers modelled how both the ages of stars in galaxies and what those stars are made from translate into the colour of light that they produce.

The team said their simulations showed that colours of galaxies can also help diagnose how they evolve.

While red and blue galaxies are relatively common, rare green galaxies are likely to be at an important stage in their evolution, when they are rapidly turning from blue – when new stars and planets are being born – to red as stars begin to burn themselves out.

Lead researcher James Trayford, PhD student in the ICC, said: “Galaxies emit a healthy blue glow while new stars and planets are being born. However, if the formation of stars is halted galaxies turn red as stars begin to age and die.

“In the real universe we see many blue and red galaxies, but these intermediate ‘green’ galaxies are more rare.

“This suggests that the few green galaxies we catch are likely to be at a critical stage in their evolution; rapidly turning from blue to red.”

Because stars form from dense gas, a powerful process is needed to rapidly destroy their gas supply and cause such dramatic changes in colour, the research found.

James added: “In a recent study we followed simulated galaxies as they changed colour, and investigated what processes caused them to change.

“We typically find that smaller green galaxies are being violently tossed around by the gravitational pull of a massive neighbour, causing their gas supply to be stripped away.

“Meanwhile, bigger green galaxies may self-destruct as immense explosions triggered by supermassive black holes at their centres can blow dense gas away.”

However, the research found that there was some hope for green galaxies as a lucky few might absorb a fresh supply of gas from their surroundings. This can revive the formation of stars and planets, and restore galaxies to a healthy blue state.

James said: “By using simulations to study how galaxy colours change, we can speed up the process of galaxy evolution from the billions of years it takes in the real Universe to just a matter of days in a computer.

“This means we don’t just see galaxy colours frozen in time, we can watch them evolve. Another advantage is that we can remove unwanted factors that may change the colours we see, such as pesky dust clouds that can prevent light escaping from galaxies.

“As the EAGLE simulations we use represent a new level of realism, we can have greater confidence in applying these results to the real universe.”




Media contacts

Dr Robert Masseybr
Royal Astronomical Society
Mob: +44 (0)7802 877 699
rm@ras.org.uk

Ms Anita Heward
Royal Astronomical Society
Mob: +44 (0)7756 034 243
anitaheward@btinternet.com

NAM 2016 press office (from Monday 27 June to Friday 1 July)
Tel: +44 (0)115 846 6993

An ISDN line and a Globelynx fixed camera are available for radio and TV interviews. To request these, please contact Robert or Anita.

Alternatively please contact the Durham University Marketing and Communications Office
Tel: +44 (0)191 334 6075



Science contact

James Trayford
Institute for Computational Cosmology
Durham University
(Available for interview on Wednesday, June 29 and Thursday, June 30, 2016)
j.w.trayford@durham.ac.uk



Images and captions

Composite image of blue, green and red galaxies: L-R Virtual images of blue, green and red galaxies produced by the EAGLE simulations. The green galaxy is caught in the act of transforming from blue to red as its gas supply runs out. Credit: James Trayford/EAGLE/Durham University

Image of blue galaxy from EAGLE simulation: Credit: James Trayford/EAGLE/Durham University

Image of green galaxy from EAGLE simulation: Credit: James Trayford/EAGLE/Durham University

Image of red galaxy from EAGLE simulation: Credit: James Trayford/EAGLE/Durham University



Further information



It's not easy being green: The evolution of galaxy colour in the EAGLE simulation, Trayford James, W, et al is being presented at the Royal Astronomical Society’s National Astronomy Meeting, at the University of Nottingham, Thursday, June 30, 2016.

The EAGLE simulation project is a flagship of the Virgo consortium, and is led by scientists in Durham, Leiden and Liverpool John Moores Universities. The simulations created by the project were carried out on the DiRAC computing facility in Durham and at the Curie computing facility based in France.




Notes for editors


The RAS National Astronomy Meeting 2016 (NAM 2016) takes place this year at the University of Nottingham from 27 June to 1 July. NAM 2016 brings together more than 550 space scientists and astronomers to discuss the latest research in their respective fields. The conference is principally sponsored by the Royal Astronomical Society and the Science and Technology Facilities Council. Follow the conference on Twitter

About Durham University:

- A world top 100 university with a global reputation and performance in research and education
- Ranked 61 globally in the QS World University Rankings 2015/16
- Ranked 31 globally for the employability of its students by blue-chip companies world-wide (QS World University Rankings 2015/16)
- Ranked 70 globally in the THE World University Rankings 2015/16
- In the global top 50 for Arts and Humanities (THE World University Rankings 2014/15)
- A member of the Russell Group of leading research-intensive UK universities
- Research at Durham shapes local, national and international agendas, and directly informs the teaching of our students
- In the 2016 Times and Sunday Times Good University Guide and the 2016 Complete University Guide, Durham was ranked fifth in the UK.
- Durham was named as The Times and Sunday Times 'Sports University of the Year 2015' in recognition of outstanding performance in both the research and teaching of sport, and student and community participation in sport at all levels.


The University of Nottingham has 43,000 students and is ‘the nearest Britain has to a truly global university, with a “distinct” approach to internationalisation, which rests on those full-scale campuses in China and Malaysia, as well as a large presence in its home city.’ (Times Good University Guide 2016). It is also one of the most popular universities in the UK among graduate employers and the winner of ‘Outstanding Support for Early Career Researchers’ at the Times Higher Education Awards 2015. It is ranked in the world’s top 75 by the QS World University Rankings 2015/16, and 8th in the UK by research power according to the Research Excellence Framework 2014. It has been voted the world’s greenest campus for four years running, according to Greenmetrics Ranking of World Universities.


Impact: The Nottingham Campaign, its biggest-ever fundraising campaign, is delivering the University’s vision to change lives, tackle global issues and shape the future.

The Science and Technology Facilities Council (STFC) is keeping the UK at the forefront of international science and has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory. Follow STFC on Twitter

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.


The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

Follow the RAS on Twitter



Planet-Devouring Star Reveals Possible Limestone Crumbs

Artist's impression of the surface of the massive, planet-like body being devoured by the white dwarf SDSSJ1043+0855. The Keck Observatory and Hubble Space Telescope data (shown in inset) show calcium and carbon, the presence of which can be explained with a model suggesting the surface of the planet may have been encrusted in limestone (calcium-carbonate). This material was removed from the surface of the massive rocky body, probably through large-scale collisions, subsequently shredded into a disk of material, and accreted by the white dwarf star (ringed object seen in the planet's sky). Credit: A. Hara/C. Melis/W. M. Keck Observatory 


MAUNAKEA, HI A group of researchers using the W. M. Keck Observatory have discovered a planet-like body that may have been encrusted in limestone and is having its surface layers devoured by its deceased host star. In addition to extending a relatively new method of determining the chemical composition of planets to examine their internal structure, the team found that the rocky material being accreted by the star could be comprised of minerals that are typically associated with marine life processes here on Earth.

The team – comprised of Carl Melis of University of California, San Diego and Patrick Dufour of the Universitie de Montreal – is announcing their findings at the 228th meeting of the American Astronomical Society this week.

Building on past observations of the white dwarf called SDSSJ1043+0855 (the dead core of a star that originally was a few times the mass of the Sun), which has been known to be gobbling up rocky material in its orbit for almost a decade, the team used Keck Observatory’s HIRES instrument fitted to the 10-meter Keck I telescope as well as data from the Hubble Space Telescope to measure and characterize the material being accreted by the star.

What they found is that the white dwarf appears to be accreting the outer-most layers of a differentiated, rocky extrasolar body (i.e., the surface of massive, planet-like object) from its extant planetary system.

“Spectroscopic observations of the white dwarf allowed us to measure the abundances of the rocky material as it is being accreted and filtered through the star’s atmosphere in real time,” Melis said. “We can see the material that used to make up this planet being accreted and replenished on a daily timescale. What we see is what the rock was made of.”

This may be the single best tool astronomers have to determine the chemical composition of planets, according to Luca Rizzi, Support Astronomer at Keck Observatory.

“We've known for some time that examining the accreted remains of rocky planets in the atmosphere of their host white dwarf star can give bulk chemical composition information, and now it looks like we can even hone in on specific layers of an accreted body in some fortuitous cases,” Melis said.

Determining the chemical composition or structure of planets outside of the Solar system to date has been elusive at best. “It’s a huge issue in exo-planetology right now,” Melis said. “The major exoplanet identifying methods can't tell you what a planet is made of or what it's structure is.”

While the finding will provide a new angle for scientists to study the chemical composition and structure of rocky planets, the possibility that life may have contributed to the inferred mineralogy certainly intrigued the team.

The researchers’ finding shows that SDSSJ1043+0855 is accreting the surface of a body that has large enhancements of carbon. This feature — combined with mild enhancements of calcium and oxygen — points to the possibility of the material coming in the form of calcium-carbonate, a mineral that is often associated with shelled marine organisms here on Earth. Calcium-carbonate is attractive as a mineral constituent of this planet-like body as incorporating and entraining carbon in rocky objects (especially their surfaces) is difficult. The terrestrial planets in our Solar system are said to live in a “carbon desert” since they are so heavily depleted in this element — the planetary surface being accreted by this white dwarf star could have as much as several hundred times more carbon than the surface of the Earth.

“This method allows us to truly get a glimpse of what aliens might be standing on,” Melis said. “In this particular case, the presence of such high levels of carbon is unique and really needs to be explained. Our choice of calcium-carbonate as a potential carrier of the carbon provides a natural way for it to be locked up in the planet and eventually delivered to the white dwarf star, is entirely consistent with the observations in hand, and of course is suggestive. That’s really the hidden subtext. When people think about finding extra-terrestrial life, they think about Hollywood dramatizations. But the first evidence of life outside of our Solar system will probably come in a much subtler form. More likely than not, it’s going to come as a nuanced signature that may not be immediately recognizable.”

Non-biological processes can produce calcium-carbonate too, so its presence isn't necessarily a smoking gun, even if it is confirmed. “There’s a lot of hoops to jump through before we can settle on the conclusion that life was involved in what we are observing,” Dufour said.

Specifically, the inferred presence of calcium-carbonate came from examining the atomic leftovers of the planet accretion event in the atmosphere of the white dwarf star – after the presumed dust from the planet’s demolished surface was consumed by the white dwarf. The next step will be to look at the dust in a mineral state before it falls into the star, to both confirm its composition and to measure its concentration.

“Future observations with the James Webb Space Telescope can confirm calcium-carbonate if it is present. If we are able to get to that point, then you have to ask: Is there enough there for it to be produced with natural processes?” Melis said.

While the presence of the calcium-carbonate is still in question, the paper shows strong evidence that the accreted material is almost certainly coming from the outer layers of a planet-like object and that white dwarf stars hold promise in informing on the structure of planets outside of the Solar system.

The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

HIRES (the High-Resolution Echelle Spectrometer) produces spectra of single objects at very high spectral resolution, yet covering a wide wavelength range. It does this by separating the light into many "stripes" of spectra stacked across a mosaic of three large CCD detectors. HIRES is famous for finding planets orbiting other stars. Astronomers also use HIRES to study distant galaxies and quasars, finding clues to the Big Bang.
Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

By Steve Jefferson

Media Contact

Steve Jefferson
W. M. Keck Observatory
(808) 881-3827
sjefferson@keck.hawaii.edu

Science Contact

Carl Melis
University of California, San Diego
(858) 534-6627
cmelis@ucsd.edu


Wednesday, June 29, 2016

Space Team Discovers Universe is Self-Cleaning

A small glimpse of one region, a tenth of the full area of the Herschel ATLAS images. Everything in this image, apart from the picture of the Moon, which has just been placed there to show the area of sky covered by the survey and the small square that shows the area covered by the Hubble Deep Field, consists of far-infrared emission from cosmic dust. The faint wisps are far-infrared emission from dust grains in the Milky Way but everything else in the image is a dusty galaxy. There are approximately 6000 dusty galaxies detected in this image, while the entire survey contains roughly half a million dusty galaxies, from galaxies similar to our own, to violently star-forming and very dusty galaxies that are being seen as they were over ten billion years ago. This image also shows how the field of hidden astronomy has evolved. The Hubble Deep Field was the first area surveyed by a dust sensitive camera called SCUBA almost 20 years ago. Five galaxies were found and the observations took 50 hrs, meaning it took 10 hours observing time to detect a galaxy. The Herschel-ATLAS maps released today cover an area 100,000 times larger and it took Herschel only 5 seconds on average to detect a galaxy in these images Credit: The Herschel ATLAS team and the European Space Agency. Click for a larger image


An illustration of the time reach of the Herschel ATLAS and the kinds of objects it has discovered. The Big Bang occurred 13.7 billion years ago. The points in the diagram (approximately 40,000) show some of the Herschel ATLAS objects. The survey discovered nearby galaxies fairly similar to our own (see galaxies to the top left), and also galaxies that are so far away that we see them as they were only two billion years after the Big Bang. The figure to the bottom right shows a detailed image made with the Atacama Large Millimetre Array of one of these early galaxies. The spectacular ‘Einstein ring’ shows that the far-infrared emission from this source has been gravitationally lensed by the gravitational field of an intervening galaxy. These ultra-distant galaxies are forming stars at a rate 1000 times greater than in the Milky Way and are shrouded by dust from the view of optical telescopes. These violently star-forming and dusty galaxies are the ancestors of the galaxies around us in the Universe today. Credit: The Herschel ATLAS team, the European Space Agency, ALMA and NRAO. Click for a larger image 


An international team of astronomers today (29 June) released a gazetteer of the hidden universe, which reveals the unseen sources of energy found over the last 12 billion years of cosmic history. Professor Haley Gomez of Cardiff University presented this catalogue of the Universe’s hidden energy sources, made with the ESA Herschel Space Observatory, at the National Astronomy Meeting in Nottingham.

About half of the light emitted by stars and galaxies is absorbed by interstellar grains, tiny solid particles that are found everywhere in the space between the stars. The missing fifty per cent has been a huge obstacle for astronomers trying to understand the births and lives of galaxies.

When the European Space Agency (ESA) Herschel Space Observatory launched in 2009 it meant that, for the first time, it was possible to track down this hidden energy. The missing light is re-emitted by the dust grains into far-infrared radiation, detected by the Herschel telescope. For the last seven years, an international team of over 100 astronomers has been analysing the images from the largest Herschel survey, named the Herschel Astrophysical Terahertz Large Area Survey (the Herschel ATLAS). Today sees the release of their first catalogues of the hidden universe.

The Herschel ATLAS discovered about half a million far-infrared sources. The size of the survey means that the survey contains both large numbers of nearby galaxies like our own, which can be detected with conventional optical telescopes, and very distant galaxies whose light has taken billions of years to reach us. The most distant galaxies in the survey are being seen as they were 12 billion years ago, only shortly after the Big Bang. They are so dusty that they are virtually impossible to detect with standard telescopes and are often gravitationally magnified by intervening galaxies. These early systems are the distant ancestors of galaxies like our own.

Dr Elisabetta Valiante, also of Cardiff University, and the lead author of one of the papers describing the catalogues, says: “The exciting thing about our survey is that it encompasses almost all of cosmic history, from the violent star-forming systems full of dust and gas in the early universe that are essentially galaxies in the process of formation, to the much more subdued systems we see around us today.”

The huge size of the survey has meant that, for the first time, it has also been possible to study the changes that have occurred in galaxies comparatively recently in cosmic history. The team has shown that even only one billion years in the past, a small fraction of the age of the universe, galaxies were forming stars faster and contained more dust than galaxies today.

According to Dr Nathan Bourne of the University of Edinburgh, and the lead author of the other paper describing the catalogues: “We were surprised to find that we didn’t need to look far in the past to see signs of galaxy evolution. Our results show that the reason for this evolution is that galaxies used to contain more dust and gas in the past, and the universe is gradually becoming cleaner as the dust is used up.”

The catalogues and maps of the hidden universe are a triumph for the Herschel team. They will be vital tools for astronomers trying to explore the history of galaxies and the wider cosmos.

The catalogues and maps of the hidden universe are a triumph for the Herschel team. They will be vital tools for astronomers trying to explore the history of galaxies and the wider cosmos.

Dr Loretta Dunne, another Cardiff University scientist, and co-leader of the project adds: “Before Herschel we only knew of a few hundred such dusty sources in the distant universe and we could only effectively 'see' them in black and white. Herschel, with its five filters, has given us the equivalent of technicolour, and the colours of the galaxies tell us about their distances and temperatures. So now we have half a million galaxies we can use to map out the hidden star formation in the universe.”

The H-ATLAS survey is a core part of the EU Research Executive Agency programme the Herschel Extragalactic Project (HELP). HELP brings together H-ATLAS and other extragalactic surveys carried out by Herschel, and combines these with major surveys by other observatories to provide a lasting legacy from the Herschel mission. This data release from the H-ATLAS team is coordinated with data releases this week from the HELP team and the Herschel Multi-tiered Extragalactic Survey (HerMES). Prof Seb Oliver of the University of Sussex leads HELP and HerMES. He says: “It is fantastic to see these high quality data products emerge from H-ATLAS, I have no doubt that astronomers will be using these for decades to come”.

Göran Pilbratt, the Herschel Project Scientist adds: “Although Herschel made its last observation in 2013, current and future generations of astronomers will find the H-ATLAS maps and catalogues essential for finding their way around the hidden universe.”



Media contacts

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699
rm@ras.org.uk

Ms Anita Heward
Royal Astronomical Society
Mob: +44 (0)7756 034 243
anitaheward@btinternet.com

NAM 2016 press office
Tel: +44 (0)115 846 6993

An ISDN line and a Globelynx fixed camera are available for radio and TV interviews. To request these, please contact Robert or Anita.



Science contacts

Dr Nathan Bourne
University of Edinburgh
bourne@roe.ac.uk

Dr Loretta Dunne (co-Principal Investigator of the Herschel-ATLAS)
Cardiff University
dunnel6@cardiff.ac.uk

Prof Haley Gomez
Cardiff University
haley.gomez@astro.cf.ac.uk

Dr Elisabetta Valiante
Cardiff University
elisabetta.valiante@astro.cf.ac.uk

Prof Steve Eales (co-Principal Investigator of the Herschel ATLAS)
Cardiff University
steve.a.eales@gmail.com

Dr Goran Pilbratt (Project Scientist of the Herschel Space Observatory)
European Space Agency
gpilbratt@cosmos.esa.int

Prof Seb Oliver (Principal Investigator of the Herschel Legacy Programme)
University of Sussex



Images and captions


https://chrisnorth.github.io/herschel-atlas-3d/
One of the maps of the hidden universe created by the H-ATLAS team. The left-hand image shows one of the maps, in which two of the dimensions are positions in the sky and the third dimension is cosmic time. Each point shows one of the H-ATLAS galaxies. The right-hand image shows the H-ATLAS galaxies in a slice of cosmic time (the slice is shown by the box in the left-hand image). Below the right-hand figure, click on ‘increase z’ to travel backwards in time and on ‘decrease z’ to travel forwards in time. Credit: The H-ATLAS team, GAMA, Chris North



Further information

The new work will appear in papers by Bourne, N. et al. 2016, and Valiante, E. et al. 2016, both submitted to Monthly Notices of the Royal Astronomical Society. 



Notes for Editors


The RAS National Astronomy Meeting 2016 (NAM 2016) takes place this year at the University of Nottingham from 27 June to 1 July. NAM 2016 brings together more than 500 space scientists and astronomers to discuss the latest research in their respective fields. The conference is principally sponsored by the Royal Astronomical Society, the Science and Technology Facilities Council. Follow the conference on Twitter
 
The University of Nottingham has 43,000 students and is ‘the nearest Britain has to a truly global university, with a “distinct” approach to internationalisation, which rests on those full-scale campuses in China and Malaysia, as well as a large presence in its home city.’ (Times Good University Guide 2016). It is also one of the most popular universities in the UK among graduate employers and the winner of ‘Outstanding Support for Early Career Researchers’ at the Times Higher Education Awards 2015. It is ranked in the world’s top 75 by the QS World University Rankings 2015/16, and 8th in the UK by research power according to the Research Excellence Framework 2014. It has been voted the world’s greenest campus for four years running, according to Greenmetrics Ranking of World Universities.

Impact: The Nottingham Campaign, its biggest-ever fundraising campaign, is delivering the University’s vision to change lives, tackle global issues and shape the future.

The Science and Technology Facilities Council (STFC) is keeping the UK at the forefront of international science and has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. STFC's Astronomy and Space Science programme provides support for a wide range of facilities, research groups and individuals in order to investigate some of the highest priority questions in astrophysics, cosmology and solar system science. STFC's astronomy and space science programme is delivered through grant funding for research activities, and also through support of technical activities at STFC's UK Astronomy Technology Centre and RAL Space at the Rutherford Appleton Laboratory. STFC also supports UK astronomy through the international European Southern Observatory. Follow STFC on Twitter.

This research has been funded by grants from the Science and Technology Facilities Council and the Cosmicdust, Cosmicism, Herschel Legacy Program projects funded by the European Union. The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

Follow the RAS on Twitter


Hubble Reveals Stellar Fireworks in 'Skyrocket' Galaxy

Kiso 5639, KUG 1138+327
Credit: NASA, ESA, and D. Elmegreen (Vassar College), B. Elmegreen (IBM's Thomas J. Watson Research Center), J. Sánchez Almeida, C. Munoz-Tunon, and M. Filho (Instituto de Astrofísica de Canarias), J. Mendez-Abreu (University of St. Andrews), J. Gallagher (University of Wisconsin-Madison), M. Rafelski (NASA Goddard Space Flight Center), and D. Ceverino (Center for Astronomy at Heidelberg University).  Release images


Fireworks shows are not just confined to Earth's skies. NASA's Hubble Space Telescope has captured a spectacular fireworks display in a small, nearby galaxy, which resembles a July 4th skyrocket.

A firestorm of star birth is lighting up one end of the diminutive galaxy Kiso 5639. The dwarf galaxy is shaped like a flattened pancake, but because it is tilted edge-on, it resembles a skyrocket, with a brilliant blazing head and a long, star-studded tail.

Kiso 5639 is a rare, nearby example of elongated galaxies that occur in abundance at larger distances, where we observe the universe during earlier epochs. Astronomers suggest that the frenzied star birth is sparked by intergalactic gas raining on one end of the galaxy as it drifts through space.

"I think Kiso 5639 is a beautiful, up-close example of what must have been common long ago," said lead researcher Debra Elmegreen of Vassar College, in Poughkeepsie, New York. "The current thinking is that galaxies in the early universe grow from accreting gas from the surrounding neighborhood. It's a stage that galaxies, including our Milky Way, must go through as they are growing up."

Observations of the early universe, such as Hubble's Ultra Deep Field, reveal that about 10 percent of all galaxies have these elongated shapes, and are collectively called "tadpoles." But studies of the nearby universe have turned up only a few of these unusual galaxies, including Kiso 5639. The development of the nearby star-making tadpole galaxies, however, has lagged behind that of their peers, which have spent billions of years building themselves up into many of the spiral galaxies seen today.

Elmegreen used Hubble's Wide Field Planetary Camera 3 to conduct a detailed imaging study of Kiso 5639. The images in different filters reveal information about an object by dissecting its light into its component colors. Hubble's crisp resolution helped Elmegreen and her team analyze the giant star-forming clumps in Kiso 5639 and determine the masses and ages of the star clusters.

The international team of researchers selected Kiso 5639 from a spectroscopic survey of 10 nearby tadpole galaxies, observed with the Grand Canary Telescope in La Palma, Spain, by J. Sánchez Almeida and collaborators at the Instituto de Astrofísica de Canarias. The observations revealed that in most of those galaxies, including Kiso 5639, the gas composition is not uniform.

The bright gas in the galaxy's head contains fewer heavier elements (collectively called "metals"), such as carbon and oxygen, than the rest of the galaxy. Stars consist mainly of hydrogen and helium, but cook up other "heavier" elements. When the stars die, they release their heavy elements and enrich the surrounding gas.

"The metallicity suggests that there has to be rather pure gas, composed mostly of hydrogen, coming into the star-forming part of the galaxy, because intergalactic space contains more pristine hydrogen-rich gas," Elmegreen explained. "Otherwise, the starburst region should be as rich in heavy elements as the rest of the galaxy."

Hubble offers a detailed view of the galaxy's star-making frenzy. The telescope uncovered several dozen clusters of stars in the galaxy's star-forming head, which spans 2,700 light-years across. These clusters have an average age of less than 1 million years and masses that are three to six times larger than those in the rest of the galaxy. Other star formation is taking place throughout the galaxy but on a much smaller scale. Star clusters in the rest of the galaxy are between several million to a few billion years old.

"There is much more star formation going on in the head than what you would expect in such a tiny galaxy," said team member Bruce Elmegreen of IBM's Thomas J. Watson Research Center, in Yorktown Heights, New York. "And we think the star formation is triggered by the ongoing accretion of metal-poor gas onto a part of an otherwise quiescent dwarf galaxy."

Hubble also revealed giant holes peppered throughout the galaxy's starburst head. These cavities give the galaxy's head a Swiss-cheese appearance because numerous supernova detonations — like firework aerial bursts — have carved out holes of rarified superheated gas.

The galaxy, located 82 million light-years away, has taken billions of years to develop because it has been drifting through an isolated "desert" in the universe, devoid of much gas.

What triggered the starburst in such a backwater galaxy? Based on simulations by Daniel Ceverino of the Center for Astronomy at Heidelberg University in Germany, and other team members, the observations suggest that less than 1 million years ago, Kiso 5639's leading edge encountered a filament of gas. The filament dropped a large clump of matter onto the galaxy, stoking the vigorous star birth.

Debra Elmegreen expects that in the future other parts of the galaxy will join in the star-making fireworks show. "Galaxies rotate, and as Kiso 5639 continues to spin, another part of the galaxy may receive an infusion of new gas from this filament, instigating another round of star birth," she said.

The team's results have been accepted for publication in The Astrophysical Journal.

Other team members include Casiana Muñoz-Tuñón and Mercedes Filho (Instituto de Astrofísica de Canarias, Canary Islands), Jairo Mendez-Abreu (University of St. Andrews, United Kingdom), John Gallagher (University of Wisconsin-Madison), and Marc Rafelski (NASA Goddard Space Flight Center, Greenbelt, Maryland).


Contact

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu

Debra Elmegreen
Vassar College, Poughkeepsie, New York
elmegreen@vassar.edu

Source: HubbleSite

Tuesday, June 28, 2016

VLA J2130+12: Clandestine Black Hole May Represent New Population

VLA J213002.08+120904
Credit X-ray: NASA/CXC/Univ. of Alberta/B.Tetarenko et al; 
Optical: NASA/STScI; Radio: NSF/AUI/NRAO/Curtin Univ./J. Miller-Jones


Tour of VLA J2130+12 (video)

animation



Astronomers have identified the true nature of an unusual source in the Milky Way galaxy. As described in our latest press release, this discovery implies that there could be a much larger number of black holes in the Galaxy that have previously been unaccounted for.

The result was made by combining data from many different telescopes that detect various forms of light, each providing key pieces of information. These telescopes included NASA's Chandra X-ray Observatory, the Hubble Space Telescope, NSF's Karl G. Jansky Very Large Array (VLA), Green Bank Telescope, Arecibo Observatory, and the European Very Long Baseline Interferometry Network.

The collaborative nature of this study is depicted in this multi-panel graphic. The large panel shows a composite Chandra and optical image of the globular cluster M15 located in our galaxy, where the X-ray data are purple and the optical data are red, green and blue. The source being studied here is bright in radio waves, as shown in the close-up VLA image, but the Chandra data reveal it can only be giving off a very small amount of X-rays.

This new study indicates this source, called VLA J213002.08+120904 (VLA J2130+12 for short), contains a black hole a few times the mass of our Sun that is very slowly pulling in material from a companion star. At this paltry feeding rate, VLA J2130+12 was not previously flagged as a black hole since it lacks some of the telltale signs that black holes in binary systems typically display.

Previously, most astronomers thought that VLA J2130+12 was probably a distant galaxy. Precise measurements from the radio telescopes showed that this source was actually well within our Galaxy and about five times closer to us than M15. Hubble data identified the companion star in VLA J2130+12 having only about one-tenth to one-fifth the mass of the Sun.

The observed radio brightness and the limit on the X-ray brightness from Chandra allowed the researchers to rule out other possible interpretations, such as an ultra-cool dwarf star, a neutron star, or a white dwarf pulling material away from a companion star.

Because this study only covered a very small patch of sky, the implication is that there should be many of these quiet black holes around the Milky Way. The estimates are that tens of thousands to millions of these black holes could exist within our Galaxy, about three to thousands of times as many as previous studies have suggested.

A paper describing these results appeared in the Astrophysical Journal. The authors were Bailey Tetarenko (University of Alberta), Arash Bahramian (Alberta), Robin Aranson (Alberta), James Miller-Jones (International Center for Radio Astronomy Research), Serena Repetto (Technion), Craig Heinke (Alberta), Tom Maccarone (Texas Tech University), Laura Chomiuk (Michigan State Univsersity), Gregory Sivakoff (Alberta), Jay Strader (Michigan State), Franz Kirsten (ICRAR), and Wouter Vlemmings (Chalmers University of Technology).

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


Fast Facts for VLA J2130+12:

Scale: Main image is 2.6 arcmin across (about 5.4 light years); inset image is 6 arcseconds across (about 0.2 light years)
Coordinates (J2000): RA 21h 21m 58s | Dec +12° 10’ 00.02"
Constellation: Pegasus
Observation Date: 12 pointings between Aug 2000 and Oct 2013
Observation Time: 63 hours 25 min (2 days 15 hours 25 min).
Obs. ID: 675, 1903, 2412, 2413, 4572, 9584, 11029, 11886, 11030, 13420, 13710, 14618
Instrument: ACIS
References: Tetarenko, B., 2016, ApJ (accepted); arXiv:1605.00270
Color Code: X-ray (Purple); Optical (Red, Green and Blue); Radio (Green)
Distance Estimate: About 7,200 light years

Innovative Gemini/CHFT Partnership Explores a Hot Jupiter

Artistʻs view of a newborn giant planet like the one newly discovered at the immediate vicinity of the very active infant star V830 Tau, as might be seen by an observer located close to the giant planet.  Download image | (Credit: Mark A. Garlick markgarlick.com)



Brightness and magnetic spots at the surfaces of V830 Tau induce spectral perturbations much larger than those caused by the reflex motion of the detected giant planet. Activity perturbations are shown in the top panel, with the blue arrow depicting the spectral velocity shift (scaled up by 20x) that activity generates. The bottom panel illustrates the combined effects of activity and of the detected planet on the spectrum of V830 Tau, with the blue / green / red arrows respectively showing the velocity shifts induced by activity, by the giant planet, and by both (scaled up by 20x). Click on the links for animations of the profile distortions induced by the spotted star, and by the spotted star plus the planet. (Credit: Jean-François Donati)


For the last 20 years the giant planets known as hot Jupiters have presented astronomers with a puzzle. How did they settle into orbits 100 times closer to their host stars than our own Jupiter is to the Sun? An international team of astronomers has announced this week1 the discovery of a newborn hot Jupiter, orbiting an infant sun — only 2 million years old, the stellar equivalent of a week-old human baby. The discovery that hot Jupiters can already be present at such an early stage of star-planet formation represents a major step forward in our understanding of how planetary systems form and evolve. 

For this discovery, the team monitored a 2 million-year-old infant star called V830 Tau, located in the Taurus stellar nursery, some 430 light-years away. Over the 1.5 months of the campaign, a regular 4.9-day “wobble” in the velocity of the host star revealed a giant planet almost as massive as Jupiter, orbiting its host star at a distance of only one-twentieth that of the Sun to the Earth distance. “Our discovery demonstrates for the first time that such bodies can be generated at very early stages of planetary formation, and likely play a central role in shaping the overall architecture of planetary systems” explains Jean-François Donati, CNRS astronomer at IRAP / OMP2 and lead author of a new paper in the current issue of the journal Nature.

The team used the twin spectropolarimeters ESPaDOnS and Narval to monitor V830 Tau for a total of 47 hours.  ESPaDOnS is mounted at the 3.6-m Canada-France-Hawaii Telescope3 (CFHT) on Maunakea and can be fiber-fed from either CFHT itself, or via GRACES, a 300-m optical-fiber link from the nearby 8 meter Gemini North telescope.  The team used ESPaDOnS in both modes, providing the opportunity to monitor the star using light from the Gemini North telescope when the instrument was unavailable at CFHT.

The team also used Narval, mounted at the 2-meter Télescope Bernard Lyot4 (TBL) atop Pic du Midi in the French Pyrénées.  “Using all three telescopes was essential for monitoring regularly V830 Tau throughout our campaign and for detecting its giant planet” stresses Lison Malo, CFHT astronomer, a coauthor of the study and leader in coordinating the observations.

In our Solar System, small rocky planets like the Earth are found near the Sun, whereas gas giants like Jupiter and Saturn orbit much further out.  “The discovery in 1995 of a giant planet flying very close to its host star took us by surprise and revolutionized the field” recalls Claire Moutou, CNRS astronomer at CFHT and a coauthor of this new study. Theoretical work indicates that such planets can only form in the cold and icy outer regions of the protoplanetary disc in which both the central star and surrounding planets are born. Some, however, migrate inwards without falling into their host star, thus becoming hot Jupiters.

“Planet formation models offer two competing explanations of how and when this migration of hot Jupiters occurred. Either it happened early while these planets were still forming, or much later, with some planets being kicked closer to their stars due to the interaction of multiple planets, or both” explains Clément Baruteau, CNRS astronomer at IRAP / OMP and a coauthor of this study. “Our discovery demonstrates that the first, earlier option is taking place; it revives the long-running debate about how and when this migration occurs, and brings us one step forward in our understanding of how planetary systems form”.

Among the known hot Jupiters, some feature strongly-tilted or even upside-down orbits, suggesting they were knocked into close orbits by interactions with other planets or neighboring stars. Others orbit above the host star’s equator, hinting at a more gentle formation process in the form of an inward drift through the disc.

“The young hot Jupiter we just detected comes as the first evidence that early disc migration is also happening” says Andrew Collier Cameron of the University of St Andrews, a coauthor of the study.


Contacts:

Claire Moutou
CFHT, Hawaii
Phone: +1-8088857944
moutou@cfht.hawaii.edu

Jean-François Donati
IRAP / OMP, Fr
Phone: +33-561332917
jean-francois.donati@irap.omp.eu



View CFHT release.

The novel collaboration between the Gemini Observatory and Canada-France-Hawai‘i Telescope (CFHT) called GRACES (Gemini Remote Access to CFHT ESPaDOnS Spectrograph), helped to characterize a “hot Jupiter” around the T-Tauri star V830 Tau. The work appears in the current advanced online issue of the journal Nature

GRACES uses an innovative 270-meter fiber cable to transport light from the Gemini 8-meter telescope to the ESPaDOnS Spectrograph at CFHT. The system began operating in late 2015 and now is a popular option allowing Gemini and CFHT users to perform high-resolution optical spectroscopy with Gemini North’s larger mirror.

The Nature paper is available online (subscription required) and is summarized in the press release from Observatoire Midi Pyrenees in Toulouse, France and CFHT that follows (release is reproduced verbatim from original): Newborn Giant Planet Grazes its Sun



“SPIRou and SPIP, the twin new-generation instruments built for CFHT and TBL by our team and scheduled for first light in 2017 and 2019 respectively, will offer vastly superior performances for such programs, and will soon allow us to explore the formation of new worlds with unprecedented sensitivity”, adds Louise Yu, a coauthor of the study and PhD student in observational exoplanet science at IRAP / OMP.

1 The paper describing the discovery, published in Nature, is available here

2 IRAP (Institut de Recherche en Astrophysique et Planétologie) is a research lab part of OMP (Observatoire Midi-Pyrénées) located in Toulouse (France), and under dual supervision from CNRS / INSU (Centre National de la Recherche Scientifique / Institut National des Sciences de l’Univers) and UFTMiP / UPS (Université Fédérale Toulouse Midi-Pyrénées / Université Paul Sabatier)


3 CFHT is operated by the National Research Council of Canada, CNRS/INSU in France and the University of Hawaii

4 TBL is operated by IRAP / OMP, CNRS / INSU and UFTMiP / UPS

Monday, June 27, 2016

Jupiter Awaits Arrival of Juno

Jupiter imaged using the VISIR instrument on the VLT

Two faces of Jupiter

Comparison of VISIR and visible light views of Jupiter 


Videos
 
Jupiter imaged using the VISIR instrument on the VLT
Jupiter imaged using the VISIR instrument on the VLT


Spectacular VLT images of Jupiter presented just days before the arrival of the Juno spacecraft

In preparation for the imminent arrival of NASA’s Juno spacecraft, astronomers have used ESO’s Very Large Telescope to obtain spectacular new infrared images of Jupiter. They are part of a campaign to create high-resolution maps of the giant planet. These observations will inform the work to be undertaken by Juno over the coming months, helping astronomers to better understand the gas giant ahead of Juno’s close encounter.

A team led by Leigh Fletcher of the University of Leicester in the United Kingdom are presenting new images of Jupiter at the UK’s Royal Astronomical Society’s National Astronomy Meeting in Nottingham. Obtained with the VISIR instrument on ESO’s Very Large Telescope, the new images are part of a focused effort to improve understanding of Jupiter’s atmosphere prior to the arrival of NASA’s Juno spacecraft [1] in July this year.

The campaign has involved the use of several telescopes based in Hawaii and Chile, as well as contributions from amateur astronomers around the world. The maps do not just give snapshots of the planet, they also reveal how Jupiter’s atmosphere has been shifting and changing in the months prior to Juno’s arrival.

The Juno spacecraft was launched in 2011, and has travelled nearly 3000 million kilometres to reach the Jovian system. Spacecraft can collect data free from the limitations affecting telescopes on Earth so with that in mind, it might seem surprising that this ground-based campaign was considered so important.

Leigh Fletcher describes the significance of this research in preparing for Juno’s arrival: “These maps will help set the scene for what Juno will witness in the coming months. Observations at different wavelengths across the infrared spectrum allow us to piece together a three-dimensional picture of how energy and material are transported upwards through the atmosphere.”

Capturing sharp images through the Earth’s constantly shifting atmosphere is one of the greatest challenges faced by ground-based telescopes. This glimpse of Jupiter’s own turbulent atmosphere, rippling with cooler gas clouds, was possible thanks to a technique known as lucky imaging. Sequences of very short exposures were taken of Jupiter by VISIR, producing thousands of individual frames. The lucky frames, where the image is least affected by the atmosphere’s turbulence, are selected and the rest discarded. Those selected frames are aligned and combined to produce remarkable final pictures like the ones shown here.

Glenn Orton, leader of the ground-based campaign in support of Juno’s mission, elaborates on why the preparatory observations from Earth are so valuable: “The combined efforts of an international team of amateur and professional astronomers have provided us with an incredibly rich dataset over the past eight months. Together with the new results from Juno, the VISIR dataset in particular will allow researchers to characterise Jupiter’s global thermal structure, cloud cover and distribution of gaseous species.”

Whilst the modern Juno’s mission to unveil the mighty Jupiter will bring new and highly anticipated results, its way has been paved by ground-based efforts here on Earth.

Notes

[1] The Juno spacecraft was named after the mythological wife of the god Jupiter. Just like his planetary counterpart, Jupiter veiled himself in clouds to hide his mischief, and only Juno was able to peer through them to see his true nature.

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 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. 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 a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.


Links


Contacts

Leigh Fletcher
University of Leicester
United Kingdom
Tel: +44 116 252 3585
Email:
leigh.fletcher@leicester.ac.uk

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

Robert Massey
Deputy Executive Director, Royal Astronomical Society
United Kingdom
Tel: +44 (0)20 7292 3979
Email:
rm@ras.org.uk

Anita Heward
Royal Astronomical Society
Cell: +44 (0)7756 034 243
Email:
anitaheward@btinternet.com


Source: ESO

X-ray Echoes of a Shredded Star Provide Close-up of 'Killer' Black Hole





Now astronomers using archival observations from Swift, the European Space Agency's (ESA) XMM-Newton observatory and the Japan-led Suzaku satellite have identified the reflections of X-ray flares erupting during the event. Led by Erin Kara, a postdoctoral researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park (UMCP), the team has used these light echoes, or reverberations, to map the flow of gas near a newly awakened black hole for the first time.

"While we don't yet understand what causes X-ray flares near the black hole, we know that when one occurs we can detect its echo a couple of minutes later, once the light  has reached and illuminated parts of the flow," Kara explained. "This technique, called X-ray reverberation mapping, has been previously used to explore stable disks around black holes, but this is the first time we've applied it to a newly formed disk produced by a tidal disruption."

In this artist's rendering, a thick accretion disk has formed around a supermassive black hole following the tidal disruption of a star that wandered too close. Stellar debris has fallen toward the black hole and collected into a thick chaotic disk of hot gas. Flashes of X-ray light near the center of the disk result in light echoes that allow astronomers to map the structure of the funnel-like flow, revealing for the first time strong gravity effects around a normally quiescent black hole. Credits: NASA/Swift/Aurore Simonnet, Sonoma State University


Stellar debris falling toward a black hole collects into a rotating structure called an accretion disk. There the gas is compressed and heated to millions of degrees before it eventually spills over the black hole's event horizon, the point beyond which nothing can escape and astronomers cannot observe. The Swift J1644+57 accretion disk was thicker, more turbulent and more chaotic than stable disks, which have had time to settle down into an orderly routine. The researchers present the findings in a paper published online in the journal Nature on Wed., June 22.

One surprise from the study is that high-energy X-rays arise from the inner part of the disk. Astronomers had thought most of this emission originated from a narrow jet of particles accelerated to near the speed of light.

In blazars, the most luminous galaxy class powered by supermassive black holes, jets produce most of the highest-energy emission.

"We do see a jet from Swift J1644, but the X-rays are coming from a compact region near the black hole at the base of a steep funnel of inflowing gas we're looking down into," said co-author Lixin Dai, a postdoctoral researcher at UMCP. "The gas producing the echoes is itself flowing outward along the surface of the funnel at speeds up to half the speed of light."

X-rays originating near the black hole excite iron ions in the whirling gas, causing them to fluoresce with a distinctive high-energy glow called iron K-line emission. As an X-ray flare brightens and fades, the gas follows in turn after a brief delay depending on its distance from the source.

"Direct light from the flare has different properties than its echo, and we can detect reverberations by monitoring how the brightness changes across different X-ray energies," said co-author Jon Miller, a professor of astronomy at the University of Michigan in Ann Arbor.

Swift J1644+57 is one of only three tidal disruptions that have produced high-energy X-rays, and to date it remains the only event caught at the peak of this emission. These star shredding episodes briefly activate black holes astronomers wouldn't otherwise know about. For every black hole now actively accreting gas and producing light, astronomers think nine others are dormant and dark. These quiescent black holes were active when the universe was younger, and they played an important role in how galaxies evolved. Tidal disruptions therefore offer a glimpse of the silent majority of supersized black holes.

Images from Swift's Ultraviolet/Optical (white, purple) and X-Ray telescopes (yellow and red) were combined in this composite of Swift J1644+57, an X-ray outburst astronomers classify as a tidal disruption event. The event is seen only in the X-ray image, which is a 3.4-hour exposure taken on March 28, 2011. The outburst was triggered when a passing star came too close to a supermassive black hole. The star was torn apart, and much of the gas fell toward the black hole. To date, this is the only tidal disruption event emitting high-energy X-rays that astronomers have caught at peak luminosity. Credits: NASA/Swift/Stefan Immler.  Click here for an unlabeled version of this image.


"If we only look at active black holes, we might be getting a strongly biased sample," said team member Chris Reynolds, a professor of astronomy at UMCP. "It could be that these black holes all fit within some narrow range of spins and masses. So it’s important to study the entire population to make sure we’re not biased."

The researchers estimate the mass of the Swift J1644+57 black hole at about a million times that of the sun but did not measure its spin. With future improvements in understanding and modeling accretion flows, the team thinks it may be possible to do so.     

ESA's XMM-Newton satellite was launched in December 1999 from Kourou, French Guiana. NASA funded elements of the XMM-Newton instrument package and provides the NASA Guest Observer Facility at Goddard, which supports use of the observatory by U.S. astronomers. Suzaku operated from July 2005 to August 2015 and was developed at the Japanese Institute of Space and Astronautical Science, which is part of the Japan Aerospace Exploration Agency, in collaboration with NASA and other Japanese and U.S. institutions.

NASA's Swift satellite was launched in November 2004 and is managed by Goddard. It is operated in collaboration with Penn State University in University Park, the Los Alamos National Laboratory in New Mexico, and Orbital Sciences Corp. in Dulles, Virginia, with international collaborators in the U.K., Italy, Germany and Japan.


Editor: Ashley Morrow


Saturday, June 25, 2016

NASA's K2 Finds Newborn Exoplanet Around Young Star

When a planet such as K2-33b passes in front of its host star, it blocks some of the star's light. Observing this periodic dimming, called a transit, from continual monitoring of a star's brightness, allows astronomers to detect planets outside our solar system with a high degree of certainty. This Neptune-sized planet orbits a star that is between 5 and 10 million years old. In addition to the planet, the star hosts a disk of planetary debris, seen as a bright ring encircling the star. Youtube

K2-33b, shown in this illustration, is one of the youngest exoplanets detected to date. It makes a complete orbit around its star in about five days. 
Credits: NASA/JPL-Caltech.

This image shows the K2-33 system, and its planet K2-33b, compared to our own solar system. The planet has a five-day orbit, whereas Mercury orbits our sun in 88 days. The planet is also nearly 10 times closer to its star than Mercury is to the sun. Credits: NASA/JPL-Caltech


Astronomers have discovered the youngest fully formed exoplanet ever detected. The discovery was made using NASA's Kepler Space Telescope and its extended K2 mission, as well as the W. M. Keck Observatory on Mauna Kea, Hawaii. Exoplanets are planets that orbit stars beyond our sun.

The newfound planet, K2-33b, is a bit larger than Neptune and whips tightly around its star every five days. It is only 5 to 10 million years old, making it one of a very few newborn planets found to date.

"Our Earth is roughly 4.5 billion years old," said Trevor David of Caltech in Pasadena, lead author of a new study published online June 20, 2016, in the journal Nature. "By comparison, the planet K2-33b is very young. You might think of it as an infant." David is a graduate student working with astronomer Lynne Hillenbrand, also of Caltech.

Planet formation is a complex and tumultuous process that remains shrouded in mystery. Astronomers have discovered and confirmed roughly 3,000 exoplanets so far; however, nearly all of them are hosted by middle-aged stars, with ages of a billion years or more. For astronomers, attempting to understand the life cycles of planetary systems using existing examples is like trying to learn how people grow from babies to children to teenagers, by only studying adults.

"The newborn planet will help us better understand how planets form, which is important for understanding the processes that led to the formation of Earth," said co-author Erik Petigura of Caltech.

The first signals of the planet's existence were measured by K2. The telescope's camera detected a periodic dimming of the light emitted by the planet's host star, a sign that an orbiting planet could be regularly passing in front of the star and blocking the light. Data from the Keck Observatory validated that the dimming was indeed caused by a planet, and also helped confirm its youthful age.

Infrared measurements from NASA's Spitzer Space Telescope showed that the system's star is surrounded by a thin disk of planetary debris, indicating that its planet-formation phase is wrapping up. Planets form out of thick disks of gas and dust, called protoplanetary disks, that surround young stars.

"Initially, this material may obscure any forming planets, but after a few million years, the dust starts to dissipate," said co-author Anne Marie Cody, a NASA Postdoctoral Program fellow at NASA's Ames Research Center in California's Silicon Valley. "It is during this time window that we can begin to detect the signatures of youthful planets with K2." 

A surprising feature in the discovery of K2-33b is how close the newborn planet lies to its star. The planet is nearly 10 times closer to its star than Mercury is to our sun, making it hot. While numerous older exoplanets have been found orbiting very tightly to their stars, astronomers have long struggled to understand how more massive planets like this one wind up in such small orbits. Some theories propose that it takes hundreds of millions of years to bring a planet from a more distant orbit into a close one -- and therefore cannot explain K2-33b, which is quite a bit younger.

The science team says there are two main theories that may explain how K2-33b wound up so close to its star. It could have migrated there in a process called disk migration that takes hundreds of thousands of years. Or, the planet could have formed "in situ" -- right where it is. The discovery of K2-33b therefore gives theorists a new data point to ponder.

"After the first discoveries of massive exoplanets on close orbits about 20 years ago, it was immediately suggested that they could absolutely not have formed there, but in the past several years, some momentum has grown for in situ formation theories, so the idea is not as wild as it once seemed," said David.

"The question we are answering is: Did those planets take a long time to get into those hot orbits, or could they have been there from a very early stage? We are saying, at least in this one case, that they can indeed be there at a very early stage," he said.

Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder.


Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425

elizabeth.landau@jpl.nasa.gov

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

michele.johnson@nasa.gov

Felicia Chou
NASA Headquarters, Washington
202-358-0257

felicia.chou@nasa.gov

Written by Whitney Clavin
Editor: Tony Greicius