Exoplanets - Planets Beyond Our Solar System

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Credit: NASA/JPL-Caltech

Protoplanetary Disk

This artist's concept shows a very young star encircled by a disk of gas and dust, the raw materials from which rocky planets such as Earth are thought to form.

Source: NASA/CalTech - Spitzer- Newsroom

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Hubble Detects Organic Molecule on an Extrasolar Planet

The media advisory is reproduced below:

March 14, 2008

J.D. Harrington
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov

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


MEDIA ADVISORY: M08-058

Hubble Detects Organic Molecule on an Extrasolar Planet

WASHINGTON - NASA will hold a media teleconference at 2 p.m. EDT on Wednesday, March 19, to report on the first-ever detection of the organic molecule methane in the atmosphere of a planet orbiting a distant star.

Though the planet is too hot to support life as we know it, the finding demonstrates the ability to detect organic molecules spectroscopically around Earth-like planets in habitable zones around stars.

Briefing participants are:
- Dr. Mark Swain, NASA Jet Propulsion Laboratory, Pasadena, Calif.
- Dr. Sara Seager, Massachusetts Institute of Technology, Cambridge

This unique discovery, made with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), will be featured in the March 20 issue of the journal Nature.

To participate in the teleconference, reporters must contact Ray Villard at 410-338-4514 or Cheryl Gundy at 410-338-4707 at the Space Telescope Science Institute by noon on March 19 for the call-in number and passcode. At the start of the briefing, images and supporting graphics will be posted on the Web at:

_http://hubblesite.org/news/2008/11

Audio of the teleconference will be streamed live on NASA's Web site at:

_http://www.nasa.gov/newsaudio

For more information about NASA's Hubble Space Telescope on the Web, visit:

_http://www.nasa.gov/hubble

- end -

Source: NASA Media Advisory M08-058

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Hubble Finds First Organic Molecule on an Exoplanet

March 19, 2008 02:00 PM (EST)

News Release Number: STScI-2008-11


NASA's Hubble Space Telescope (HST) has made the first detection ever of an organic molecule in the atmosphere of a Jupiter-sized planet orbiting another star. This breakthrough is an important step in eventually identifying signs of life on a planet outside our solar system.

The molecule found by Hubble is methane, which under the right circumstances can play a key role in prebiotic chemistry — the chemical reactions considered necessary to form life as we know it.

This discovery proves that Hubble and upcoming space missions, such as NASA's James Webb Space Telescope, can detect organic molecules on planets around other stars by using spectroscopy, which splits light into its components to reveal the "fingerprints" of various chemicals.

"This is a crucial stepping stone to eventually characterizing prebiotic molecules on planets where life could exist," said Mark Swain of NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., who led the team that made the discovery. Swain is lead author of a paper appearing in the March 20 issue of Nature.

The discovery comes after extensive observations made in May 2007 with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS). It also confirms the existence of water molecules in the planet's atmosphere, a discovery made originally by NASA's Spitzer Space Telescope in 2007. "With this observation there is no question whether there is water or not — water is present," said Swain.

The planet now known to have methane and water is located 63 light-years away in the constellation Vulpecula. Called HD 189733b, the planet is so massive and so hot it is considered an unlikely host for life. HD 189733b, dubbed a "hot Jupiter," is so close to its parent star it takes just over two days to complete an orbit. These objects are the size of Jupiter but orbit closer to their stars than the tiny innermost planet Mercury in our solar system. HD 189733b's atmosphere swelters at 1,700 degrees Fahrenheit, about the same temperature as the melting point of silver.

Though the star-hugger planet is too hot for life as we know it, "this observation is proof that spectroscopy can eventually be done on a cooler and potentially habitable Earth-sized planet orbiting a dimmer red dwarf–type star," Swain said. The ultimate goal of studies like these is to identify prebiotic molecules in the atmospheres of planets in the "habitable zones" around other stars, where temperatures are right for water to remain liquid rather than freeze or evaporate away.

The observations were made as the planet HD 189733b passed in front of its parent star in what astronomers call a transit. As the light from the star passed briefly through the atmosphere along the edge of the planet, the gases in the atmosphere imprinted their unique signatures on the starlight from the star HD 189733.

The astronomers were surprised to find that the planet has more methane than predicted by conventional models for "hot Jupiters." "This indicates we don't really understand exoplanet atmospheres yet," said Swain.

"These measurements are an important step to our ultimate goal of determining the conditions, such as temperature, pressure, winds, clouds, etc., and the chemistry on planets where life could exist. Infrared spectroscopy is really the key to these studies because it is best matched to detecting molecules," said Swain.

Swain's co-authors on the paper include Gautam Vasisht of JPL and Giovanna Tinetti of University College, London/European Space Agency.

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

Whitney Clavin/Jane Platt
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-4673/0880
whitney.clavin@jpl.nasa.gov/jane.platt@jpl.nasa.gov

Lars Lindberg Christensen
ESA/Hubble, Garching, Germany
011-49-89-320-06-306
lars@eso.org

Source: HubbleSite - Newsdesk

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Artist's View of Extrasolar Planet HD 189733b

News Release Number: STScI-2008-11

ABOUT THIS IMAGE:

This illustration depicts the extrasolar planet HD 189733b with its parent star peeking above its top edge. Astronomers used the Hubble Space Telescope to detect methane and water vapor in the Jupiter-size planet's atmosphere. They made the finding by studying how light from the host star filters through the planet's atmosphere.

Object Name: HD 189733b

Image Type: Artwork

Credit: NASA, ESA, and G. Bacon (STScI)

Source: HubbleSite - Newsdesk

Edited March 20, 2008 by Waspie_Dwarf

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Methane Absorption Spectrum

News Release Number: STScI-2008-11

Object Name: HD 189733b

Image Type: Illustration

Credit: NASA, ESA, and A. Feild (STScI)

Source: HubbleSite - Newsdesk

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Location of HD 189733 on the Sky

News Release Number: STScI-2008-11

Object Name: HD 189733b

Image Type: Astronomical/Illustration

Credit: NASA, ESA, A. Fujii, and Z. Levay (STScI)

Source: HubbleSite - Newsdesk

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THE (SUPER)WASP FACTORY FINDS 10 NEW PLANETS IN THE LAST 6 MONTHS

The Royal Astronomical Society / National Astronomy Meeting 2008 press release is reproduced below:

ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE
Ref.: PN 08/17 (NAM 08)

Issued by RAS Press Officers:

Dr Robert Massey
Tel: +44 (0)20 7734 3307 / 4582
Mobile: +44 (0)794 124 8035
E-mail: rm(at)ras.org.uk

Anita Heward
Tel: +44 (0)1483 420904
Mobile: +44 (0)7756 034243
E-mail: anitaheward(at)btinternet.com

NATIONAL ASTRONOMY MEETING PRESS ROOM (31 MARCH - 4 APRIL ONLY):
Tel: +44 (0)2890 975262
975263
975264

NAM 2008
_http://nam2008.qub.ac.uk

Royal Astronomical Society
_http://www.ras.org.uk

CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE


RAS PN 08/17 (NAM 08) (EMBARGOED): THE (SUPER)WASP FACTORY FINDS 10 NEW PLANETS IN THE LAST 6 MONTHS

In the last 6 months an international team of astronomers have used two batteries of cameras, one in the Canary Islands and one in South Africa, to discover 10 new planets in orbit around other stars (commonly known as extrasolar planets). The results from the Wide Area Search for Planets (SuperWASP) will be announced by team member Dr Don Pollacco of Queen's University Belfast, in his talk at the RAS National Astronomy Meeting (NAM 2008) on Tuesday 1 April.

Scientists have found more than 270 extrasolar planets since the first one was discovered in the early 1990s. Most of these are detected through their gravitational influence on the star they orbit - as it moves the planet pulls on the star, tugging it back and forth. However, making these discoveries depends on looking at each star over a period of weeks or months and so the pace of discovery is fairly slow.

SuperWASP uses a different method. The two sets of cameras watch for events known as transits, where a planet passes directly in front of a star and blocks out some of the star's light, so from the Earth the star temporarily appears a little fainter. The SuperWASP cameras work as robots, surveying a large area of the sky at once and each night astronomers have data from millions of stars that they can check for transits and hence planets. The transit method also allows scientists to deduce the size and mass of each planet.

Each possible planet found using SuperWASP is then observed by astronomers working at the Nordic Optical Telescope on La Palma, the Swiss Euler Telescope in Chile and the Observatoire de Haute Provence in southern France, who use precision instruments to confirm or reject the discovery.

45 planets have now been discovered using the transit method, and since they started operation in 2004 the SuperWASP cameras have found 15 of them - making them by far the most successful discovery instruments in the world. The SuperWASP planets have masses between a middleweight 0.5 and a huge 8.3 times that of Jupiter, the largest planet in our Solar System. A number of these new worlds are quite exotic. For example, a year on WASP-12B (its orbital period) is just 1.1 days. The planet is so close to its star that its daytime temperature could reach a searing 2300 degrees Celsius.

Dr Pollacco is delighted with the results. 'SuperWASP is now a planet-finding production line and will revolutionise the detection of large planets and our understanding of how they were formed. It's a great triumph for European astronomers.'

FURTHER INFORMATION (INCLUDING IMAGES):

SuperWASP
Project website
_http://www.superwasp.org

Images of the SuperWASP Cameras


1) _http://star.pst.qub.ac.uk/~dlp/SWASP_1.jpg - a close up of the 8 SuperWASP-North cameras.


2) _http://star.pst.qub.ac.uk/~dlp/SWASP_2.jpg - an aerial view of the SuperWASP-North cameras (courtesy of Damon Hart-Davis, _http://d.hd.org).


3) _http://star.pst.qub.ac.uk/~dlp/SWASP_3.jpg - the SuperWASP-South instrument.

Image of the Euler (Swiss) Telescope dome

_http://www.cosmograil.org/images/euler-dome.jpg

Image of the SOPHIE spectrograph at the Observatoire de Haute Provence
_http://www.obs-hp.fr/www/guide/sophie/sophie.html

RAS National Astronomy Meeting
_http://nam2008.qub.ac.uk

RAS home page
_http://www.ras.org.uk

NOTES FOR EDITORS

The SuperWASP cameras are operated by a consortium including the Isaac Newton Group on La Palma, the Instituto Astrofisica Canarias, the University of Keele, the University of Leicester, the Open University, Queen's University Belfast and St Andrew?s University.

Follow up [observations] of SuperWASP exoplanet candidates are obtained at the Nordic Optical Telescope on La Palma, the Swiss Euler Telescope at La Silla, Chile (in collaboration with colleagues at Geneva Observatory) and at the 1.93-m telescope of the Observatoire de Haute-Provence in France (in collaboration with colleagues at the Institut d'Astrophysique de Paris and the Laboratoire d'Astrophysique de Marseille).

The SuperWASP cameras in La Palma and South Africa are operated with funding provided by the UK's Science and Technology Facilities Council (STFC).

The RAS National Astronomy Meeting (NAM 2008) is hosted by Queen's University Belfast. It is principally sponsored by the RAS and the Science and Technology Facilities Council (STFC). NAM 2008 is being held together with the UK Solar Physics (UKSP) and Magnetosphere, Ionosphere and Solar-Terrestrial (MIST) spring meetings.

CONTACTS

Dr Don Pollacco
Astrophysics Research Centre
School of Mathematics and Physics
Queen's University Belfast
University Road
Belfast BT7 1NN
UK
E-mail: d.pollacco(at)qub.ac.uk
Tel: +44 (0)28 9097 3512

Dr Ian Skillen
Isaac Newton Group of Telescopes
Correos 321
E-38700, Santa Cruz de La Palma
Canary Islands
Spain
E-mail: wji(at)ing.iac.es
Tel: +34 922 425439

Dr Coel Hellier
Astrophysics Group
School of Physical and Geographical Sciences
Lennard-Jones Laboratories
Keele University
Staffordshire ST5 5BG
UK
E-mail: ch(at)astro.keele.ac.uk
Tel: +44 (0)1782 584243

Dr Richard West
Department of Physics and Astronomy
University of Leicester
University Road
Leicester LE1 7RH
UK
E-mail: richard.west(at)astro.le.ac.uk
Tel: +44 (0)116 252 5206

Dr Carole Haswell
Department of Physics and Astronomy
The Open University
Walton Hall
Milton Keynes MK7 6AA
UK
E-mail: C.A.Haswell(at)open.ac.uk
Tel: +44 (0)1908 653396

Dr Leslie Hebb
Department of Physics and Astronomy
University of St Andrews
North Haugh
St Andrews
Fife KY16 9SS
UK
E-mail: leslie.hebb(at)st-andrews.ac.uk
Tel: +44 (0)1334 461674

Source: RAS - NAM Press Release

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CHANCE OF FINDING EARTHLIKE PLANETS ON THE 'RISE' AS UK ASTRONOMERS DEPLOY NEW CAMERA

The Royal Astronomical Society / National Astronomy Meeting 2008 press release is reproduced below:

ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE
Ref.: PN 08/19 (NAM 10)

Issued by RAS Press Officers:

Dr Robert Massey
Tel: +44 (0)20 7734 3307 / 4582
Mobile: +44 (0)794 124 8035
E-mail: rm(at)ras.org.uk

Anita Heward
Tel: +44 (0)1483 420904
Mobile: +44 (0)7756 034243
E-mail: anitaheward(at)btinternet.com

NATIONAL ASTRONOMY MEETING PRESS ROOM (31 MARCH - 4 APRIL ONLY):
Tel: +44 (0)2890 975262
975263
975264

NAM 2008
_http://nam2008.qub.ac.uk

Royal Astronomical Society
_http://www.ras.org.uk/

CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE


RAS PN 08/19 (NAM 10) (EMBARGOED): CHANCE OF FINDING EARTHLIKE PLANETS ON THE 'RISE' AS UK ASTRONOMERS DEPLOY NEW CAMERA

Using a revolutionary new camera, UK astronomers have a real chance of being the first to find Earth-like planets around other stars. PhD student Neale Gibson of Queen's University Belfast will present the first results from the RISE instrument in his talk on Wednesday 2 April at the RAS National Astronomy Meeting in Belfast.

RISE is a new fast camera designed by astronomers at Queen's University, Belfast (QUB) in collaboration with Liverpool John Moores University and is now installed on the 2m Liverpool Telescope on the Canary Island of La Palma.

Since the early 1990s, astronomers have found more than 200 planets in orbit around stars other than our Sun (so-called 'extrasolar' planets). These have been detected through two techniques that are particularly sensitive to massive planets in orbit close to their parent star. Firstly, planets can be found through their gravitational pull on the star they orbit - as the extrasolar planet moves the star wobbles back and forth. By measuring this movement astronomers can deduce the presence of a planet. Secondly, the transit search technique looks for the dip in brightness of a star as a planet passes in front of it.

However, neither of these techniques is currently good enough to find small extrasolar planets similar to the Earth. So far most of those found are so-called 'hot Jupiters' - large gas giant planets very close to their parent star.

The RISE camera is primarily designed to find Earth-mass planets in orbit around stars already known to host hot Jupiters. With RISE, scientists will search for extrasolar planets using a technique called transit timing, which may provide a short cut to discovering Earth-like planets with existing technology.

Transit timing works on the principle that an isolated hot Jupiter planet orbiting its host will have a constant orbital period (i.e. its 'year' remains the same) and therefore it will block out the light from its parent star in a regular and predictable way. During the planet's transit events, RISE can very accurately measure the rise and fall in the amount of light reaching the Earth from the parent star - the camera can be used to pinpoint the time of the centre of the event to within 10 seconds.

By observing and timing their transits, astronomers hope to detect small changes in the orbital periods of known hot Jupiters caused by the gravitational pull of other planets in the same system. In the right circumstances, even planets as small as the Earth could be found in this way.

Gibson comments, 'The potential of transit timing is the result of some very simple physics, where multi-planet systems will gravitationally kick one another around in their orbits - an effect often witnessed in our own Solar System. If Earth-mass planets are present in nearby orbits (which is predicted by current Hot-Jupiter formation theories) we will see their effect on the orbit of the larger transiting planets.'

'RISE will allow us to observe and time the transits of extrasolar planets very accurately, which gives us the sensitivity required to detect the effect of even small Earth-mass planets'.

FURTHER INFORMATION INCLUDING IMAGES

Images of extrasolar planets and RISE camera
http://star.pst.qub.ac.uk/~ng/pics.shtml

Neale Gibson, Queen's University Belfast - more information on RISE project and transit timing

_http://star.pst.qub.ac.uk/~ng

RISE camera
_http://star.pst.qub.ac.uk/swasp/Rise_Commissioning_Photos.htm
_http://telescope.livjm.ac.uk/Info/TelInst/Inst/RISE/index.php

Liverpool Telescope home page
_http://telescope.livjm.ac.uk
_http://telescope.livjm.ac.uk/Info/TelInst/Inst/RISE/index.php (and RISE pages)

RAS National Astronomy Meeting
_http://nam2008.qub.ac.uk

RAS home page
_http://www.ras.org.uk/

NOTES FOR EDITORS

RISE is supported by The Queen's University of Belfast, Liverpool John Moores University, the Science and Technology Facilities Council and Prof John Meaburn of The University of Manchester.

The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council.

The RAS National Astronomy Meeting (NAM 2008) is hosted by Queen's University Belfast. It is principally sponsored by the RAS and the Science and Technology Facilities Council (STFC). NAM 2008 is being held together with the UK Solar Physics (UKSP) and Magnetosphere, Ionosphere and Solar-Terrestrial (MIST) spring meetings.

CONTACT

Neale Gibson
Astrophysics Research Centre
Physics Building
Queen's University Belfast
Belfast BT7 1NN
E-mail: ngibson07(at)qub.ac.uk
Web: _http://star.pst.qub.ac.uk/~ng/
Tel: +44 (0)28 9097 2585

Source: RAS - NAM Press Release

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Astronomers find baby planet'

The University of St Andrews press release is reproduced below:

Tuesday 01 April 2008

Scottish astronomers have found a baby planet still in the stages of forming and encased within a 'womb' of gas.

The embryonic planet, thought to be the youngest ever seen, was discovered by Dr Jane Greaves of the University of St Andrews and colleagues from across the UK and the US.

The finding provides a unique view of how planets take shape, because the supporting images also shows the womb-like parent disk material from which the new planet formed. The 'protoplanet', called HL Tau b after its parent star HL Tau, could be as young as a few hundred years old.

Dr Greaves, of the School of Physics & Astronomy at St Andrews, explained, "The planet will probably take millions of years to settle down into its final form of something like Jupiter. So we really are seeing it very early - even a bit like the first cells that make up a human embryo in the womb."

The team made the discovery when studying HL Tau, a star thought to be less than 100,000 years old - 'young' when compared to the Sun which is 4600 million years old. Around 520 light years away and in the constellation of Taurus, HL Tau's unusually massive and bright surrounding disk of gas and rocky particles make it an excellent place to search for signs of forming planets.

The outcome was a result of a rare opportunity to use a large array of telescopes across the US. The 'very sharp' images taken of HL Tau and its surroundings revealed the presence of super-large rocky particles about the size of pebbles, a clue that rocky material is beginning to clump together to form planets.

The big surprise was that, as well as detecting super-large dust in the disk around HL Tau, an extra bright 'clump' was seen in the image. It confirms tentative 'nebulosity' reported a few years earlier but shows the same system in much greater detail. The finding was confirmed by readings from telescopes based at the Jodrell Bank Observatory in Cheshire and supported by computer simulations from the University of Edinburgh.

Dr Greaves comments, "We see a distinct orbiting ball of gas and dust, which is exactly how a very young protoplanet should look. In the future, we would expect this to condense out into a gas giant planet like a massive version of Jupiter. The protoplanet is about 14 times as massive as Jupiter and is about twice as far from HL Tau as Neptune is from our Sun."

The researchers think the planet may have been 'tweaked' into forming after an encounter with another young star about 1600 years go in a 'flyby' incident. They say that the planet formed because of gravitational instability in the surrounding disk, which allows small regions to separate out and cool down into self-contained structures.

"Whether the protoplanet formed in only the last few hundred years, or sometime in the 100000 years since the birth of HL Tau, the images provide a unique view of planet formation in action, and the first picture of a protoplanet still embedded in its birth material," said Dr Greaves.

Dr Greaves will talk about the discovery at the RAS National Astronomy Meeting in Belfast today (Wednesday 2 April).


ENDS


Issued by the Press Office, University of St Andrews
Contact Gayle Cook, Press Officer on 01334 467227 / 462529, mobile 07900 050 103, or email gec3@st-andrews.ac.uk
Ref: Baby planets 310308
View the latest University press releases at _www.st-andrews.ac.uk


Source: University of St Andrews Press Release

[Waspie_Dwarf]

ASTRONOMERS FIND EMBRYONIC PLANET

The Royal Astronomical Society / National Astronomy Meeting 2008 press release is reproduced below:

ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE
Issued by RAS Press Officers:

Dr Robert Massey
Tel: +44 (0)20 7734 3307 / 4582
Mobile: +44 (0)794 124 8035
E-mail: rm@ras.org.uk

Anita Heward
Tel: +44 (0)1483 420904
Mobile: +44 (0)7756 034243
E-mail: anitaheward@btinternet.com

NATIONAL ASTRONOMY MEETING PRESS ROOM (31 MARCH - 4 APRIL ONLY):
Tel: +44 (0)2890 975262
975263
975264

NAM 2008
_http://nam2008.qub.ac.uk

Royal Astronomical Society
_http://www.ras.org.uk

CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE


ASTRONOMERS FIND EMBRYONIC PLANET

Using radio observatories in the UK and US and computer simulations, a team of astronomers have identified the youngest forming planet yet seen. Team leader Dr Jane Greaves of the University of St Andrews will discuss the ‘protoplanet’ in her talk at the RAS National Astronomy Meeting in Belfast on Wednesday 2 April.

Taking advantage of a rare opportunity to use the Very Large Array (VLA) of radio telescopes in the US with the special addition of an extra telescope 50 km away, the team studied the disk of gas and rocky particles around the star HL Tau. This star is thought to be less than 100000 years old (by comparison the Sun is 4600 million years old) and lies in the direction of the constellation of Taurus at a distance of 520 light years. The disk around HL Tau is unusually massive and bright, which makes it an excellent place to search for signs of forming planets.

The VLA gives very sharp images of HL Tau and its surroundings. The team studied the system using radio emission at a wavelength of 1.3 cm, specifically chosen to search for the emission from super-large rocky particles about the size of pebbles. The presence of these pebbles is a clue that rocky material is beginning to clump together to form planets.

In the UK, scientists used the MERLIN array of radio telescopes centred on Jodrell Bank in Cheshire, to study the same system at longer wavelengths. This allowed the astronomers to confirm that the emission is from rocks and not from other sources such as hot gas. Jodrell Bank scientists Dr Anita Richards and Dr Tom Muxlow analysed the data.

The big surprise was that, as well as detecting super-large dust in the disk around HL Tau, an extra bright 'clump' was seen in the image. It confirms tentative ‘nebulosity’ reported a few years earlier at around the same position, by a team lead by Dr Jack Welch of the Berkeley-Illinois-Maryland Array. The new image shows the same system in much greater detail.

Dr Greaves comments, “We see a distinct orbiting ball of gas and dust, which is exactly how a very young protoplanet should look. In the future, we would expect this to condense out into a gas giant planet like a massive version of Jupiter. The protoplanet is about 14 times as massive as Jupiter and is about twice as far from HL Tau as Neptune is from our Sun.”

Dr Richards adds, “The new object, designated HL Tau b, is the youngest planetary object ever seen and is just 1 percent as old as the young planet found in orbit around the star TW Hydrae that made the news last year. HL Tau b gives a unique view of how planets take shape, because the VLA image also shows the parent disk material from which it formed.”

Team member Dr Ken Rice of the University of Edinburgh ran a computer simulation to find out how such a massive protoplanet could form. His animation shows a very similar body condensing out of a disk with similar properties to that actually observed around HL Tau. The planet forms because of gravitational instability in the disk, which is about half as massive as the star itself. This allows small regions to separate out and cool down into self-contained structures. This instability mechanism has been controversial, but the simulated and real data are such a good match that it seems the mechanism really does operate in nature.

Dr Rice comments, “The simulations were as realistic as we could make them and we were delighted that the results compare so well with the observations.”

One intriguing property is that XZ Tau, another young star in the same region, may have passed near HL Tau about 1600 years ago. Although not required for planet formation, it is possible that this flyby 'tweaked' the disk and helped it become unstable. This would be a very recent event in astronomical terms. Whether the proto-planet formed in only the last few hundred years, or sometime in the 100000 years since the birth of HL Tau, the images provide a unique view of planet formation in action, and the first picture of a protoplanet still embedded in its birth material.

IMAGES:

Images of HL Tau and still and movie from simulation : _http://www.roe.ac.uk/~wkmr/HLTau/HLTau.html

Figure 1: The false colour image is a map of the radio emission (at a wavelength of 1.3 cm) emitted from the region around the star HL Tau. The candidate protoplanet is marked 'b'. The bar at top left (marked 50 AU) indicates 50 times the Earth-Sun distance on the same scale, or about the size of the orbit of Pluto. HL Tau is located in the centre of the image. The star is surrounded by a dusty disc tilted to the line of sight; only the inner part is visible here but its extent is indicated by the white ellipse. The arrows show the direction of the jets of hot gas emitted as 'overspill' from the star growth process. Image: VLA and Pie Town antenna

Figure 2: This is an image from the computer simulation of HL Tau and its surrounding disk. In the model the dense clump (seen here at top right) forms with a mass of about 8 times that of Jupiter at a distance from the star about 75 times that from the Earth to the Sun. Image: Ken Rice / Royal Observatory Edinburgh


FURTHER INFORMATION

Jodrell Bank Centre for Astrophysics
_http://www.jb.man.ac.uk

University of St Andrews Astronomy Group
http://star-www.st-and.ac.uk/index.php[/color][/b]

Royal Observatory Edinburgh
_http://www.roe.ac.uk

RAS National Astronomy Meeting
_http://nam2008.qub.ac.uk

RAS home page
_http://www.ras.org.uk

Science and Technology Facilities Council
_http://www.stfc.ac.uk

NOTES FOR EDITORS

The VLA is operated by the National Radio Astronomy Observatory (USA) on behalf of United Universities, Inc.

MERLIN is operated by the University of Manchester, Jodrell Bank Observatory, on behalf of the Science and Technology Facilities Council (STFC).

The simulation ran on a supercomputer funded by the Scottish Universities Physics Alliance (SUPA).

The RAS National Astronomy Meeting (NAM 2008) is hosted by Queen’s University Belfast. It is principally sponsored by the RAS and the Science and Technology Facilities Council (STFC). NAM 2008 is being held together with the UK Solar Physics (UKSP) and Magnetosphere, Ionosphere and Solar-Terrestrial (MIST) spring meetings.

CONTACTS

Dr Jane Greaves
School of Physics and Astronomy
University of St Andrews
North Haugh
St Andrews
Fife KY16 9SS
Scotland
E-mail: jsg5@st-and.ac.uk
Tel: +44 (0)1334 463199
Mobile: +44 (0)7864 741874

Dr Anita Richards
Jodrell Bank Centre for Astrophysics
Alan Turing Building
University of Manchester
Manchester M13 9PL
U.K.
E-mail: amsr@jb.man.ac.uk
Tel: +44 (0)161 275 4124
Mobile: +44 (0)7766 065049

Dr Tom Muxlow
MERLIN/VLBI National Facility
Jodrell Bank Observatory
Cheshire SK11 9DL
U.K.
E-mail: twbm@jb.man.ac.uk
Tel: +44 (0)1477 571321 (switchboard) 572607 (direct line)

Dr Ken Rice
Institute for Astronomy
University of Edinburgh
Royal Observatory
Blackford Hill
Edinburgh
Scotland EH9 3HJ
E-mail: wkmr@roe.ac.uk
Tel : +44 (0)131 668 8384

Source: RAS - NAM Press Release

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New Laser Technology Could Find First Earth-like Planets

The Harvard-Smithsonian Center for Astrophysics press release is reproduced below:

Release No.: 2008-08
For Release: Monday, April 07, 2008 02:00:00 PM

Austin, TX - The leading method of finding planets orbiting distant stars spots mostly Jupiter-sized worlds. Technology limitations make it difficult to detect smaller planets. But that is about to change. A revolutionary laser technology being developed by scientists and engineers at the Harvard-Smithsonian Center for Astrophysics (CfA), with colleagues at MIT, will enable scientists to spot Earth-sized worlds in Earth-like orbits.

"We are at the cusp of a new era in planet searches," said CfA astrophysicist Chih-Hao Li. "With this technology we are developing, astronomers will finally be able to find the first truly Earth-like worlds in terms of size and orbit."


CfA astronomers are developing a new device that may be the first to spot Earth-like planets, like the hypothetical
world with two moons shown in this artist's concept. The "astro-comb" uses a laser to provide an ultrasensitive way
of measuring a distant star's wobbling motion, which is induced by an orbiting planet.
Credit: David A. Aguilar (CfA)

This research is published in April 3, 2008, issue of the journal Nature.

Planets orbiting other stars are much too faint and far away to be seen directly and photographed. Instead, astronomers must look for the planet's effect on its star.

While the gravity of a star tugs on a planet and holds the planet in orbit, the planet's gravity also tugs on the star. That tug makes the star wobble slightly back and forth. If the wobble is along our line of sight, then sensitive instruments called spectrographs may be able to detect it.

The size of the wobble depends on the planet's heft (mass) and its distance from the star. The larger the mass of the planet, the bigger the star's wobble will be, making larger planets easier to detect. At the same time, a planet in a tight, short-period orbit is easier to find than one in a wide, long-period orbit.

Current technology, although very stable and sensitive, isn't quite up to the task of finding Earths. The best instruments can only find 5-Earth-mass planets in tight, Mercury-like orbits.

The new device developed by Li and his colleagues, called an astro-comb, will be able to spot Earth-mass planets in Earth-like orbits. It uses ultrashort, femtosecond (one millionth of one billionth of a second) pulses of laser light, linked to an atomic clock, to provide a precise standard against which light from a star can be measured.

The astro-comb can make measurements accurate to one part in a trillion. This may increase the resolution of the wobble planet-hunting technique by about 100 times, which would allow astronomers to detect Earth-sized planets.

A prototype astro-comb will be tested this summer at CfA's Mount Hopkins Observatory in Arizona. Those tests will be used to refine the design. An improved astro-comb is destined for a project being built in the Canary Islands called the New Earths Facility. The researchers expect it to be operational sometime in 2010.

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

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
daguilar@cfa.harvard.edu

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu

Source: CfA Press Release

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New rocky planet found in constellation Leo

The University College London press release is reproduced below:

9 April 2008

Spanish and UCL (University College London) scientists have discovered a possible terrestrial-type planet orbiting a star in the constellation of Leo. The new planet, which lies at a distance of 30 light years from the Earth, has a mass five times that of our planet but is the smallest found to date. One full day on the new planet would be equivalent to three weeks on Earth.

The team of astronomers from the Spanish Research Council (CSIC) working with Dr Jean-Philippe Beaulieu, a visiting astrophysicist at UCL, made the discovery from model predictions of a new exoplanet (meaning planet outside our solar system) orbiting a star in the constellation of Leo. Simulations show that the exoplanet, dubbed GJ 436c, orbits its host star (GJ 436) in only 5.2 Earth days, and is thought to complete a revolution in 4.2 Earth days, compared to the Earth’s revolution of 24 hours and full orbit of 365 days. On Earth, a full day (sunset to sunset) coincides quite closely with the rotation period. On the new planet these two periods do not coincide, since the orbital translation period and the rotation period are very similar. For this reason, a full day on the new planet would take four planetary years, or roughly 22 Earth days.

The study, published this week in Astrophysical Journal, predicted the presence of a small exoplanet perturbing an inner planet (already known), producing changes on its orbit. A re-analysis of archival radial velocities also permitted the identification of a signal that perfectly matches the simulations and corresponds to a planet in resonance with the inner one, meaning that for every two orbits of the known planet the new planet completes one.

Ignasi Ribas, lead author of the study from CSIC, says: “After final confirmation, the new exoplanet will be the smallest found to date. It is the first one to be identified from the perturbations exerted on another planet of the system. Because of this, the study opens a new path that should lead to the discovery of even smaller planets in the near future, with the goal of eventually finding worlds more and more similar to the Earth.”

Dr Jean-Philippe Beaulieu, visiting astrophysicist at UCL Physics and Astronomy, says: “This is the fourth super-Earth planet discovered. This planet is the hot twin of the frozen super-Earth (OGLE-2005-BLG-390lb) we discovered by microlensing two years ago. Other previously discovered planets of this class are the two hot super-Earths Gl 581b and Gl 876d detected by their Doppler wobble.“

Dr Giovanna Tinetti, UCL Physics and Astronomy who recently calculated the putative properties of this planet, says: “Calculations indicate that the temperature of the planet could be within 400-700 Kelvin [127-427 Celsius], but it could locally be as low as 350 K [77 C] at the poles, depending on the type of atmosphere.”

Most of the 280 or so planets discovered to date are gas giants similar to Jupiter, although some with masses below 10 times that of the Earth have already been found. Planets with masses of between one and 10 times the Earth are often dubbed super-Earths. In this case, current models predict that the new planet is a rocky type and has a radius some 50 per cent larger than the Earth.

Notes

1. For more information, please contact Dr Jean-Philippe Beaulieu (currently based in London) on mobile +33 603 98 7311, e-mail beaulieu@iap.fr.

2. Alternatively, please contact Jenny Gimpel in the UCL Media Relations Office on tel: +44 (0)20 7679 9726, mobile: +44 (0)7747 565 056, out of hours +44 (0)7917 271 364, e-mail: j.gimpel@ucl.ac.uk.

3. ‘A 5 M super-Earth orbiting GJ 436? The power of near-grazing transits’ is published this week in Astrophysical Journal. Journalists can obtain copies of the paper by contacting the UCL Media Relations Office. A video is also available.

4. The work was carried out by Ignasi Ribas and Andreu Font-Ribera, Spanish Research Council (CSIC) and the Institute for Space Studies of Catalonia (IEEC), and Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris and visiting scientist at UCL (University College of London).

5. The research was partly supported by the HOLMES project (Hunting for Low Mass Extrasolar planets).

Source: UCL press release

With thanks to Corthos for sending me the link to this story, and apologies for taking so long to post it.

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Planets by the Dozen

May 8, 2008: You know the planets of our solar system, each a unique world with its own distinctive appearance, size, and chemistry. Mars, with its bitter-cold, rusty red sands; Venus, a fiery world shrouded in thick clouds of sulfuric acid; sideways Uranus and its strange vertical rings. The variety is breathtaking.

Now imagine the variety that must exist in hundreds of solar systems. There may be worlds out there that make Venus seem hospitable and Uranus positively upright. Only 20 years ago, astronomers were unsure whether any such worlds existed beyond our own solar system. Now, they've found more than 280 of them, each with its own planetary "personality," each a fascinating example of what a world can be.

Above: Artist T. Riecken's concept of planets orbiting a distant sun-like star.

Yet the heyday of planetary discovery is only just beginning. This fall, astronomers will start a massive search for new planets by observing about 11,000 nearby stars over 6 years. This number dwarfs the roughly 3,000 stars that astronomers have searched to date for the presence of planets. Scientists estimate that the NASA-funded project, called MARVELS (Multi-object Apache Point Observatory Radial Velocity Exoplanet Large-area Survey), will find at least 150 new planets—perhaps many more.

"We're looking in particular for giant planets like Jupiter," says Jian Ge, principal investigator for MARVELS and an astronomer at the University of Florida in Gainesville. Ge likens big planets to "beacons of a lighthouse" signaling the presence of entire solar systems. "Once we find a big planet around a star, we know that smaller planets could be there, too."

MARVELS will do much more than just catalogue a few hundred more planets. By surveying the Jupiter-like planets around such a large number of stars, MARVELS aims to give astronomers the data they need to test competing theories for how planetary systems form and evolve.

To look at so many stars, MARVELS will use a telescope that can separately image 60 stars at a time, and this number will eventually be increased to 120 stars. The telescope, which will be housed at the Apache Point Observatory in the Sacramento Mountains of New Mexico, has a 2.5 meter primary mirror and a wide field of view that covers 7 square degrees of the sky—an area that would appear 35 times larger than the Moon.

An array of 60 fiber-optic threads will carry light from the telescope's focal plane to highly sensitive interferometers. These instruments can detect tiny changes in the frequency of a star's light. How does this help find planets? Ge explains: When a star is tugged to and fro by the gravity of an orbiting planet, the star's light is shifted to and fro in frequency--an effect called the Doppler shift. The powerful gravity of Jupiter-sized planets exerts a big tug on the parent star, making them relatively easy to find using the Doppler shift method.


Above: Each of the red fiber optic cables in the MARVELS
instrument can monitor its own star allowing astronomers
to survey many stars at once. [more]

If Ge and his colleagues see a star's frequency slowly increasing and decreasing in a repeating cycle over days, weeks, or months, it's a good bet that a planet is there.

Scientists are keen to learn what kinds of stars have orbiting gas giants. One theory for how these planets form predicts that stars rich in heavy elements such as silicon, oxygen, and nickel should be more likely to have Jupiter-like planets. Imagine a planet-forming disk surrounding such a star: The disk, like the star itself, would be rich in heavy elements. Those heavier elements would form rocky chunks in the disk, and these dense chunks would collide and merge to create a "planet seed" with strong enough gravity to gather gas around itself and grow into a behemoth.

So if MARVELS finds more gas giants around stars containing heavier elements, the survey would support this theory. But some gas giants might not need these heavy elements to form. Another theory suggests that Jupiter-like planets can arise simply because a disturbance in the planet-forming disk starts the gravitational collapse of a region of gas and dust—no seed required.


Above: The Apache Point Observatory in New Mexico
where the MARVELS survey will take place. [more]

By examining a large number of stars with a variety of heavy element fractions, MARVELS may be able to distinguish between these two ideas.

Data from MARVELS will also shed light on other questions about planet formation, such as how often the orbits of gas giants migrate closer to their stars, and how planets sometimes end up with highly eccentric orbits instead of the nearly circular orbits predicted by theory. By surveying an unprecedented number of stars, MARVELS could deliver the data scientists need to find patterns about the conditions most favorable for planet creation, knowledge that can guide future, detailed observations of individual stars.

Follow-up observations might eventually use space telescopes powerful enough to make out the rough appearance of those many worlds. The planets we know may only hint at the marvels waiting … out there.

Editor: Dr. Tony Phillips | Credit: Science@NASA

____________________________________________

More Information

Prof. Jian Ge -- leader of the MARVELS Survey

MARVELS home page (University of Florida)

NASA's Future: The Vision for Space Exploration

Source: Science@NASA

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ESA‘s roadmap to Earth-like planets

29 May 2008

TThis artist’s impression shows the surface of a possible exoplanet placed at exactly the right distance from its parent star for liquid water to exist on its surface.

Credits: ESA. Illustration by Medialab

ESA is launching a new initiative to develop a roadmap for finding Earth-like planets. Searching for rocky planets around other stars, in the hopes of finding an Earth-like world, is a top scientific goal in ESA's Cosmic Vision programme.

Achieving this ambition requires a great deal of technological development, and a constant eye on the changes taking place across this fast-moving field of research. To provide an overview of the field and a set of technological milestones that must be achieved before rocky planets can be analysed, ESA has appointed the Exoplanet Roadmap Advisory Team.

The team consists of ten exoplanet experts from across Europe and is chaired by Artie Hatzes, Director of the Thüringer Landessternwarte Tautenburg, Germany. Here, he explains the aims of the roadmap.

Prof. Artie Hatzes, Director of the Thüringer Landessternwarte Tautenburg (Germany), chairs the Exoplanet Roadmap Advisory Team. This task force has been appointed by ESA in Spring 2008 to provide an overview of this research field and to suggest a set of technological milestones that must be achieved before rocky planets can be analysed.

Credits: Artie Hatzes

What is the rationale behind the exoplanet roadmap?

The search for exoplanets is a hot research topic. It has one great goal driving it forward: to find out how many habitable Earth-like planets there might be in the galaxy.

To do this, there has to be a threefold strategy. Firstly, observers must tell us what is out there. Secondly, theoreticians must tell us what we might expect to find. And thirdly, technologists must tell us which instruments we need to find these things.

The rationale behind the roadmap is to get these groups of people working together in order to identify the milestones along the way to finding other Earths.


What is the ultimate goal of exoplanet research?

Ultimately, we want to obtain an image of an Earth-like planet and spectroscopically analyse its atmosphere. This will tell us whether there’s oxygen, ozone, carbon dioxide and water vapour in its atmosphere. When we see all the right constituents for life then we can say, “Yes, that is a twin to Earth." The roadmap will provide us with a plan to reach that goal.

How will you be guided in your creation of the roadmap?

We will ask the exoplanet research community to submit white papers informing us of their work. These will allow us to check what has been done so far, the status of current and planned observations, the theories of planets that could hold life, and more importantly, what the developing areas of study are likely to be. It is such an exciting field that it attracts the best and the brightest. This drives the research in innovative ways that have really accelerated progress to date. We now know that there is an incredible diversity of planetary systems to be studied.

Why is exoplanetary research important?

As a scientist, I want to know whether our solar system is unique. If I look up, I see thousands of stars and right from school was told that they are similar to the Sun. So how many of them have planets similar to Earth?

Also, looking at exoplanets can allow us to test our theories of planet formation. You can have a great theory for how our Solar System formed but the real test is whether it can explain exoplanet systems as well. Each new exoplanet system we find is a new laboratory where we can test our ideas.

Then, there is the philosophical aspect. Are we unique? I think that's why this research excites the public, because they all ask the question: are we alone? The only way to answer that is go out there and look.

What do you hope to achieve with this roadmap?

Once we have collected the white papers, the team will put them all together. By early next year we will have a concrete roadmap. This will include what we have to do scientifically and technologically in the next year, the next 5-10 years, and then the next 20 years, to achieve our scientific goal of characterising Earth-like worlds.

Source: ESA - News

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Small Planet, Small Star

The National Science Foundation press release is reproduced below:

Press Release 0793
Newly discovered extrasolar planet is the smallest known and has smallest host star

Artist's conception of the newly discovered planet MOA-2007-BLG-192Lb orbiting a brown dwarf "star" with a mass of only 6 percent of that of the Sun. Theory suggests that the 3-Earth-mass planet is made primarily of rock and ice. Observational and theoretical studies of brown dwarfs reveal that they have a magenta color due to absorption by elements such as sodium and potassium in their atmospheres. If the host star has a mass of 9 percent of that of the Sun, at the other end of the margin of error for the new microlensing data, the star would be a red dwarf about 100 times brighter than the brown dwarf, but 1000 times fainter than the Sun.

Credit: NASA's Exoplanet Exploration Program

June 2, 2008

Astronomers have discovered an extrasolar planet only three times more massive than our own, the smallest yet observed orbiting a normal star. The star itself is not large, perhaps as little as one twentieth the mass of our Sun, suggesting to the research team that relatively common low-mass stars may present good candidates for hosting Earth-like planets.
Led by David Bennett of the University of Notre Dame, the international research team presents its findings in a press conference Monday, June 2, 2008, at 11:30 a.m. CDT at the American Astronomical Society Meeting in St. Louis, Mo.

"Our discovery indicates that that even the lowest mass stars can host planets," says Bennett. "No planets have previously been found to orbit stars with masses less than about 20 percent that of the Sun, but this finding indicates that even the smallest stars can host planets."

The astronomers used a technique called gravitational microlensing to find the planet, a method that can potentially find planets one-tenth the mass of our own.

The gravitational microlensing technique, which came from Einstein's General Theory of Relativity, relies upon observations of stars that brighten when an object such as another star passes directly in front of them (relative to an observer, in this case on Earth). The gravity of the passing star acts as a lens, much like a giant magnifying glass. If a planet is orbiting the passing star, its presence is revealed in the way the background star brightens. A full explanation of the technique follows this release.

"This discovery demonstrates the sensitivity of the microlensing method for finding low-mass planets, and we are hoping to discover the first Earth-mass planet in the near future," said Bennett.

Using standard nomenclature, the star hosting the newly discovered planet is dubbed MOA-2007-BLG-192L with MOA indicating the observatory, 2007 designating the year the microlensing event occurred, BLG standing for bulge, 192 indicating the 192nd microlensing observation by MOA in that year and the L indicating the lens star as opposed to the background star further in the distance. The planet maintains the name but adds a letter designating it as an additional object in the star's solar system, so it is called MOA-2007-BLG-192Lb.

MOA-2007-BLG-192L resides 3,000 light years away and is classified as either a low-mass hydrogen burning star, one that sustains nuclear reactions in its core as our Sun does, or a brown dwarf, an object like a star yet without the mass to sustain nuclear reactions in its core. The researchers were unable to confirm which category the star fits into due to the nature of the observations and the margin of error.

With support from the National Science Foundation (NSF), Bennett has been one of the pioneers in using gravitational microlensing for detecting low mass planets. He has been working with collaborators around the world to find a number of planets that are ever closer in size to our own.

For the most recent discovery, the research collaborators took advantage of two international telescope collaborations: Microlensing Observations in Astrophysics (MOA), which includes Bennett, and the Optical Gravitational Lensing Experiment (OGLE).

Researchers in New Zealand made the initial measurements of the new planet and its star using the new MOA-II telescope at the Mt. John Observatory. The observatory's MOA-cam3 camera, in one observation, can capture an image of the sky 13 times larger than the area of the full moon. Researchers in Chile made follow-up observations using high angular resolution adaptive optics images at the Very Large Telescope at the European Southern Observatory. Data from the observations was analyzed by scientists around the world hailing from five continents.

"This discovery is very exciting because it implies Earth-mass planets can form around low-mass stars, which are very common," said Michael Briley, NSF astronomer and the officer who oversees Bennett's grant. "It is another important step in the search for terrestrial planets in the habitable zones of other stars, and it would not have been possible without the international collaboration of professional and amateur astronomers devoted to measuring these signals."

The team has written a paper about the new planet discovery and it has been accepted for publication in the Sept. 1, 2008, issue Astrophysical Journal. In addition to NSF support, Bennett is also funded by the National Aeronautics and Space Administration.

In addition to Bennett, the MOA group is made up of astronomers from Nagoya University, Konan University, Nagano National College of Technology, and Tokyo Metropolitan College of Aeronautics in Japan, as well as Massey University, the University of Auckland, Mt. John Observatory, the University of Canterbury, and Victoria University in New Zealand. The OGLE group is comprised of astronomers from Warsaw University Observatory in Poland, the Universidad de Concepción in Chile, and the University of Cambridge in England. Additional collaborators who provided the VLT data and analysis are from the Institut d'Astrophysique de Paris, the Observatoire Midi-Pyrénées, and the Observatoire de Paris in France, the European Southern Observatory in Chile, and Heidelberg University in Germany.

Notre Dame's press release is available at: http://newsinfo.nd.edu/content.cfm?topicid=28128

Related NSF press releases, including animation, audio, and video, are linked below. NSF can provide video in betacamSP format upon request.

Closer to Home
http://www.nsf.gov/news/news_summ.jsp?cntn_id=105759

A Newly Discovered Solar System Contains Scaled-Down Versions of Saturn and Jupiter
http://www.nsf.gov/news/news_summ.jsp?cntn_id=111093

-NSF-

What is Microlensing?

The gravitational microlensing technique is based on a concept first discussed by Albert Einstein in the early 20th century. When astronomers observe a star, the light waves generally travel straight from the star to the telescope. However, if another star passes directly in between, even if great distances separate the two, the gravity of the nearer object acts like a lens and magnifies the incoming light.

Telescopes cannot resolve the details of the magnified image, but they do notice a peak in light intensity, and when a planet is present around the closer star, the planet's gravity adds a small peak of its own. Additional planets reveal themselves by further altering the light signals.

Astronomers can use the light-peak features to determine how large an extrasolar planet is and how far away it is from its star. This method is 50 times more likely to detect planets of approximately twice the mass of Jupiter than it is to detect planets closer to the mass of Earth. However, even relatively tiny, low-mass objects can give a strong peak signal if alignment is perfect.

Of the nearly 300 extrasolar planets discovered to date, most were discovered using a different technique, known as the radial velocity method. This technique uses the fact that two objects orbiting each other will orbit about their common center of mass. If one object is very bright (the star) and the other is very dim (the planet), the presence of the planet is revealed by the apparent motion of the star about the common center of mass.

The motion can be detected by observing the spectrum of the star. Dark lines in the spectrum, resulting from various elements in the star's atmosphere, will appear to shift back and forth as a result of the star's motion. The back and forth motion, or wobble, reveals the size and orbit of the planet. While incredibly effective, existing technology utilizing this method has so far found mainly large, Jupiter-like planets or smaller planets that orbit too close to their host stars to harbor life, but research is ongoing.

Media Contacts
Joshua A. Chamot, NSF (703) 292-7730 jchamot@nsf.gov
William Gilroy, University of Notre Dame (574) 631-7367 gilroy.6@nd.edu

Program Contacts
Michael Briley, NSF (703) 292-4901 mbriley@nsf.gov

Principal Investigators
David Bennett, University of Notre Dame (574) 315-6621 bennett@nd.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of $5.92 billion. NSF funds reach all 50 states through grants to over 1,700 universities and institutions. Each year, NSF receives about 42,000 competitive requests for funding, and makes over 10,000 new funding awards. The NSF also awards over $400 million in professional and service contracts yearly.

Source: NSF press release