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Exoplanets - Planets Beyond Our Solar System


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#121    Waspie_Dwarf

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Posted 01 November 2007 - 01:44 AM

Astronomer's role in new planets discovery

The University of St Andrews press release is reproduced below:

31 October 2007

A St Andrews researcher is part of the leading team of planet-hunting astronomers that have announced the discovery of three new planets today (31 October 2007).  

linked-image
An artist's impression of the new planets (STFC)

Professor Andrew Collier Cameron, of the University's School of Physics & Astronomy, played an important role in the recent discovery of three planets said to be as big as Jupiter, and named WASP-3, WASP-4 and WASP-5.

Professor Cameron is a member of the Wide Area Search for Planets (WASP) team, which also includes astronomers from the University of Keele and Queen's University Belfast.   Using `super-cameras' in South Africa and the Canary Islands that monitor millions of stars over the entire sky, the latest finding makes them the only team to have found transiting planets in both the Northern and Southern hemispheres.  The team are already responsible for the discovery of two new planets named WASP-1 and WASP-2 last year.

Professor Cameron, who measured the sizes of the new extra-solar planets, said, "All three planets are similar to Jupiter, but are orbiting their stars so closely that their 'year' lasts less than two days.  These are among the shortest orbital periods yet discovered.  Being so close to their stars the surface temperatures of the planets will be more than 2000 degrees Celsius, so it is unlikely that life as we know it could survive there. But the finding of Jupiter-mass planets around other stars supports the idea that there are also many Earth-sized planets waiting to be discovered as astronomers' technology improves."

linked-image
Professor Andrew Collier Cameron

Over 200 extra-solar planets (those that orbit other stars, rather than our Sun) are currently known to astronomers.  The three new planets were found as the WASP cameras detected small dips in the brightness of the host stars, caused when planets pass in front of, or transit, them.  Studying such planets outside of our solar system allows scientists to investigate how planetary systems form.

Dr Coel Hellier of Keele University said, "When we see a transit we can deduce the size and mass of the planet and also what it is made of, so we can use these planets to study how solar systems form."

WASP-4 and WASP-5 are the first planets discovered by the WASP project's cameras in South Africa, and were confirmed by a collaboration with Swiss and French astronomers.

"These two are now the brightest transiting planets in the Southern hemisphere," said Dr Hellier.  WASP-3 meanwhile is the third planet that the team has found in the North, using the SuperWASP camera sited in the Canary Islands.  

Dr Don Pollacco, of Queen's University Belfast, said, "We are the only team to have found transiting planets in both the Northern and Southern hemispheres; for the first time we have both SuperWASP cameras running, giving complete coverage of the whole sky."

The WASP project is the most ambitious project in the world designed to discover large planets. Funding for the project comes from the three universities and the Science and Technology Facility Council.


Weblink: _www.superwasp.org/wasp_planets.htm    


ENDS


NOTE:

The discovery of WASP-3, WASP-4 and WASP-5 is being announced by the WASP project this week at an international conference on extrasolar planets in Suzhou (near Shanghai), China.

Contacts

Professor Andrew Collier Cameron, University of St Andrews.
Tel: 01334 463147
Email: Andrew.Cameron@st-and.ac.uk  

Dr Don Pollacco, QUB, WASP Project Scientist
Tel: 02890 973512
Email: d.pollacco@qub.ac.uk

Dr Coel Hellier, Keele University  
Tel: 01782 584243
Email: ch@astro.keele.ac.uk

Gill Ormrod - Science and technology Facilities Council Press Office
Tel: 01793 442012. Mobile: 0781 8013509
Email: gill.ormrod@stfc.ac.uk


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:  Trio of new planets 311007

Source: University of St Andrews Press Release

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#122    Waspie_Dwarf

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Posted 01 November 2007 - 04:16 PM

Scientists Discover New Member of Exoplanet Family

The linked-image media advisory is reproduced below:

Nov 1, 2007
Grey Hautaluoma
Headquarters, Washington
202-358-0668
grey.hautaluoma-1@nasa.gov

DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
david.c.agle@jpl.nasa.gov

Denize Springer
San Francisco State Univ.
415-405-3803
denize@sfsu.edu

Bob Sanders
University of California, Berkeley
510-643-6998
rsanders@berkely.edu

MEDIA ADVISORY: M07-151

Scientists Discover New Member of Exoplanet Family


WASHINGTON - Astronomers will announce new findings about a planetary system similar to our own at a media teleconference Tuesday, Nov. 6, at 1 p.m. EST. Funding for the study was provided by NASA and the National Science Foundation.

The briefing participants are:
- Debra Fischer - astronomer, San Francisco State University
- Geoff Marcy - astronomer, University of California, Berkeley
- Jonathan Lunine - planetary scientist, University of Arizona, Tucson
- Zlatan Tsvetanov - program scientist, NASA Headquarters, Washington

Reporters should call the Media Relations Office at NASA's Jet Propulsion Laboratory at 818-354-5011 for dial-in participation information. NASA will stream audio of the briefing live on the Web at:

At the start of the briefing, NASA will post supporting images and graphics at:

For information about NASA's planet-hunting missions, visit:

Source: NASA Media Advisory M07-151

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#123    Waspie_Dwarf

Waspie_Dwarf

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Posted 06 November 2007 - 07:27 PM

Scientists Discover Record Fifth Planet Orbiting Nearby Star
11.06.07

PASADENA, Calif. - Astronomers have announced the discovery of a fifth planet circling 55 Cancri, a star beyond our solar system. The star now holds the record for number of confirmed extrasolar planets orbiting in a planetary system.

55 Cancri is located 41 light-years away in the constellation Cancer and has nearly the same mass and age as our sun. It is easily visible with binoculars. Researchers discovered the fifth planet using the Doppler technique, in which a planet's gravitational tug is detected by the wobble it produces in the parent star. NASA and the National Science Foundation funded the research.

linked-image
Image above: This artist's concept shows
planets that orbit 55 Cancri, a star much like
our own.
Image credit: NASA/JPL-Caltech
+ Related animation


"It is amazing to see our ability to detect extrasolar planets growing," said Alan Stern, associate administrator for the Science Mission Directorate at NASA Headquarters, Washington. "We are finding solar systems with a richness of planets and a variety of planetary types comparable to our own."

The newly discovered planet weighs about 45 times the mass of Earth and may be similar to Saturn in its composition and appearance. The planet is the fourth from 55 Cancri and completes one orbit every 260 days. Its location places the planet in the "habitable zone," a band around the star where the temperature would permit liquid water to pool on solid surfaces. The distance from its star is approximately 116.7 million kilometers (72.5 million miles), slightly closer than Earth to our sun, but it orbits a star that is slightly fainter.

linked-image
Image above: This artist's concept illustrates
two planetary systems - 55 Cancri (top) and
our own.
Image credit: NASA/JPL-Caltech


"The gas-giant planets in our solar system all have large moons," said Debra Fischer, an astronomer at San Francisco State University and lead author of a paper that will appear in a future issue of the Astrophysical Journal. "If there is a moon orbiting this new, massive planet, it might have pools of liquid water on a rocky surface."

Fischer and University of California, Berkeley, astronomer Geoff Marcy, plus a team of collaborators discovered this planet after careful observation of 2,000 nearby stars with the Shane telescope at Lick Observatory located on Mt. Hamilton, east of San Jose, Calif., and the W.M. Keck Observatory in Mauna Kea, Hawaii. More than 320 velocity measurements were required to disentangle signals from each of the planets.

"This is the first quintuple-planet system," said Fischer. "This system has a dominant gas giant planet in an orbit similar to our Jupiter. Like the planets orbiting our sun, most of these planets reside in nearly circular orbits."

"Discovering these five planets took us 18 years of continuous observations at Lick Observatory, starting before any extrasolar planets were known anywhere in the universe," said Marcy, who contributed to the paper. "But finding five extrasolar planets orbiting a star is only one small step. Earth-like planets are the next destination."

The planets around 55 Cancri are somewhat different from those orbiting our sun. The innermost planet is believed to be about the size of Neptune and whips around the star in less than three days at a distance from the star of approximately 5.6 million kilometers (3.5 million miles). The second planet is a little smaller than Jupiter and completes one orbit every 14.7 days at a distance from the star of approximately 18 million kilometers (11.2 million miles). The third planet, similar in mass to Saturn, completes one orbit every 44 days at a distance from the star of approximately 35.9 million kilometers (22.3 million miles). The newly discovered planet is the fourth planet. The fifth and most distant known planet is four times the mass of Jupiter and completes one orbit every 14 years at a distance from the star of approximately 867.6 million kilometers (539.1 million miles). It is still the only known Jupiter-like gas giant to reside as far away from its star as our own Jupiter is from our sun.

"This work marks an exciting next step in the search for worlds like our own," said Michael Briley, an astronomer at the National Science Foundation. "To go from the first detections of planets around sun-like stars to finding a full-fledged solar system with a planet in a habitable zone in just 12 years is an amazing accomplishment and a testament to the years of hard work put in by these investigators."

For visuals depicting the new planets on the Web, visit:

_http://www.nasa.gov/audience/formedia/telecon-20071106/

or

_http://planetquest.jpl.nasa.gov/news/ssu_images.html

For information about NASA and agency programs, visit:

_http://www.nasa.gov


Media contacts: DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Grey Hautaluoma 202-358-0668
NASA Headquarters, Washington
grey.hautaluoma-1@nasa.gov

Denize Springer 415-405-3803
San Francisco State University, Calif.
denize@sfsu.edu

Bob Sanders 510-643-6998
University of California, Berkeley
rsanders@berkeley.edu

2007-128


Source: NASA - Exploring the Universe - New Worlds

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#124    Waspie_Dwarf

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Posted 06 November 2007 - 07:32 PM

Plentiful Planetary System
11.06.07


linked-image
This artist's concept shows four of the five planets that orbit 55 Cancri, a star much like our own. The most recently discovered planet, and the fourth out from the star, looms large in the foreground. It is at least 45 times the mass of Earth, or half the mass of Saturn, and it orbits the star every 260 days. The system's three known inner planets can be seen in the background around the glowing star, while its most distant planet is not pictured. Fifty-five Cancri has produced a larger number of massive planets than our solar system.

The colors of the planets in this illustration were chosen to resemble those of our own solar system. Astronomers do not know what the planets look like.

Image credit: NASA/JPL-Caltech

Source: NASA - For Media and Press

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#125    Waspie_Dwarf

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Posted 06 November 2007 - 07:34 PM

Our Solar System's Cousin?
11.06.07


linked-image
This artist's concept illustrates two planetary systems - 55 Cancri (top) and our own. Blue lines show the orbits of planets, including the dwarf planet Pluto in our solar system. The 55 Cancri system is currently the closest known analogue to our solar system, yet there are some fundamental differences.

The similarities begin with the stars themselves, which are about the same mass and age. Both stars also host big families of planets. Our solar system has eight planets, while 55 Cancri has five, making it the record-holder for having the most known exoplanets. In fact, 55 Cancri could have additional planets, possibly even rocky ones that are too small to be seen with current technologies. All of the planets in the two systems have nearly circular orbits.

In addition, both planetary systems have giant planets in their outer regions. The giant located far away from 55 Cancri is four times the mass of our Jupiter, and completes one orbit every 14 years at a distance of five times that between Earth and the sun (about 868 million kilometers or 539 million miles). Our Jupiter completes one orbit around the sun every 11.9 years, also at about five times the Earth-sun distance (778 million kilometers or 483 million miles). Fifty-five Cancri is still the only known star besides ours with a planet in a distant Jupiter-like orbit. Both systems also contain inner planets that are less massive than their outer planets.

The differences begin with the planets' masses. The planets orbiting 55 Cancri are all larger than Earth, and represent a "souped-up" version of our own solar system. In fact, this is the first star that boasts more giant planets than our sun!

The arrangement of the planetary systems is also different. The inner four planets of 55 Cancri are all closer to the star than Earth is to the sun. The closest, about the mass of Uranus, whips around the star in just under three days at a distance of approximately 5.6 million kilometers (3.5 million miles). The second planet out from the star is a little smaller than Jupiter and completes one orbit every 14.7 days at a distance of approximately 17.9 million kilometers (11.2 million miles). The third planet out from the star is similar in mass to Saturn and completes one orbit every 44 days at a distance of approximately 35.9 million kilometers (22.3 million miles). The fourth planet is about half the mass of Saturn, orbits every 260 days and is approximately 116.7 million kilometers (72.5 million miles) away from the star.

Image credit: NASA/JPL-Caltech

Source: NASA - For Media and Press

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#126    Waspie_Dwarf

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Posted 07 November 2007 - 02:31 AM

Record 5th planet found around nearby star

The UC Berkley press release is reproduced below:

By Robert Sanders, Media Relations | 06 November 2007

linked-image
An artist's concept of the star 55 Cancri showing the newly discovered planet in the foreground – a gas giant half the mass of Saturn – and three already known inner planets (the planet farthest from the star is not pictured). All the inner planets are the size of Neptune or bigger, unlike our solar system's rocky inner planets. The colors of the planets in this illustration were chosen to resemble those of our own solar system. Astronomers do not know what the planets look like. (NASA/JPL-Caltech)

BERKELEY –  A team of American astronomers announced today (Tuesday, Nov. 6) the discovery of a record-breaking fifth planet around the nearby star 55 Cancri, making it the only star aside from the sun known to have five planets.

The discovery comes after 19 years of observations of 55 Cancri and represents a milestone for the California and Carnegie Planet Search team, which this year celebrates the 20th anniversary of its first attempts to find extrasolar planets by analyzing the wobbles they cause in their host star.

The team's long history of measurements - more than 300 for 55 Cancri alone - made the discovery of a five-planet system possible, said UC Berkeley astronomy professor Geoffrey Marcy, who with Paul Butler, now at the Carnegie Institution of Washington, began observations of many nearby stars at the University of California Lick Observatory in 1987.

The unique 55 Cancri system, located 41 light-years away in the direction of the constellation Cancer, is notable also because its clutch of four inner planets and one giant outer planet resembles our own solar system, though without an Earth or Mars.

"This system is interesting because there's a giant planet at 6 AU and four smaller planets inward of 0.8 AU, with a huge remaining gap in between, right where we would expect to find an Earth-sized planet," Marcy said.

An AU, or astronomical unit, is the average distance between the Earth and the sun, about 93 million miles.

According to lead author Debra Fischer, assistant professor of astronomy at San Francisco State University, the fifth planet is within the star's habitable zone in which water could exist as a liquid. Though the planet is a giant ball of gas, liquid water could exist on the surface of a moon or on other, rocky planets that may yet be found within the zone. "Right now, we are looking at a gap between the 260-day orbit of the new planet and the 14-year orbit of another gas giant, and if you had to bet, you'd bet that there is more orbiting stuff there."

Fischer noted that what occupies this gap has to be another planet around the size of Neptune or smaller, because anything larger would have destabilized the orbits of the other planets. All of the planets around 55 Cancri are in stable, nearly circular obits, like the eight planets in our solar system. Jupiter is located at 5.2 AU from the sun, while Mercury and Venus are closer than 0.72 AU. Earth and Mars are in the gap at 1 AU and 1.5 AU.

"We haven't found a twin of our solar system, because the four planets close to the star are all the size of Neptune or bigger," Marcy said, but he added that he's optimistic that continued observations will reveal a rocky planet within five years.

The new discovery, using data from the Lick Observatory and the W. M. Keck Observatory in Hawaii, has been accepted for publication in the Astrophysical Journal. The authors are Fischer, Marcy and their colleagues at the Carnegie Institution, San Francisco State University, UC Santa Cruz, Tennessee State University and UC Berkeley.

Fischer and Marcy also discussed their findings today during a media teleconference hosted by NASA.

In 1996, when Marcy and Butler found a Jupiter-sized planet orbiting close to 55 Cancri and circling every 14.6 days, it was only the fourth known star with an exoplanet. The second planet discovered around the star, in 2002, turned out to circle in a more distant orbit, like our own Jupiter does, although the planet was four times the weight of Jupiter. The third, also discovered in 2002, was smaller, about half the size of Saturn, and was orbiting near the star with an orbit of 44 days, slightly farther than the first planet. The fourth planet, found in 2004, was so close to the star as to be hellishly hot - a Neptune-sized planet (14 times Earth's mass) with a 2.8 day period discovered in collaboration with a team led by Barbara McArthur of the University of Texas.

Although astronomers have found nearly 250 exoplanets, only one other star, mu Ara in the southern sky, is known to have four planets.

The newly-found fifth planet around 55 Cancri is also large - around half the size of Saturn, or at least 45 times the mass of Earth - and orbiting at about 0.785 AU in 260.8 days. Because the star 55 Cancri is older and dimmer than our sun, the habitable zone - the region in which planetary temperatures can be favorable for liquid water - is closer to the star than is our sun's habitable zone, and includes the new planet.

Finding multiple planets around a star is difficult because each planet produces its own stellar wobble. Marcy compares detecting the wobble within wobbles that are caused by one of several planets to picking out a single musical note from many played simultaneously. While the ear can do that, it took Marcy more than 10 months to convince himself that a fifth wobble was buried in the data.

The Doppler technique used by the search team sees this wobble as a change in the speed with which a star moves toward or away from us. The search team can detect velocities as small as 1 meter per second, which is walking speed.

55 Cancri has produced "a rat's nest of radial velocity data," Fischer said. "We probably still don't have all the planets. We are pulling out one thread at a time, disentangling all these orbits, and it has taken a lot more data and time than we predicted. I think it's amazing what we have been able to do with the system."

Coauthors with Fischer, Marcy and Butler are Steven S. Vogt and Greg Laughlin of UC Santa Cruz; Jason T. Wright, John A. Johnson and Kathryn M. G. Peek of UC Berkeley; Gregory W. Henry of Tennessee State University's Center of Excellence in Information Systems; and David Abouav, Chris McCarthy and Howard Isaacson of San Francisco State University.

The work was supported by the University of California, NASA and the National Science Foundation.

Source: UC Berkley Press Release

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#127    Waspie_Dwarf

Waspie_Dwarf

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Posted 16 November 2007 - 06:04 PM

Planets forming in Pleiades star cluster, astronomers report

The UCLA press release is reproduced below:

By Stuart Wolpert | 11/14/2007 11:45:00 AM

Rocky terrestrial planets, perhaps like Earth, Mars or Venus, appear to be forming or to have recently formed around a star in the Pleiades ("seven sisters") star cluster, the result of "monster collisions" of planets or planetary embryos.

Astronomers using the Gemini Observatory in Hawaii and the Spitzer Space Telescope report their findings in an upcoming issue of the Astrophysical Journal, the premier journal in astronomy.

"This is the first clear evidence for planet formation in the Pleiades, and the results we are presenting may well be the first observational evidence that terrestrial planets like those in our solar system are quite common," said Joseph Rhee, a UCLA postdoctoral scholar in astronomy and lead author of the research.

The Pleiades star cluster, in the constellation Taurus, is well-known in many cultures. It is named for the seven daughters of Atlas and Pleione, who were placed by Zeus among the stars in Greek mythology and is cited in the Bible — "Can you bind the beautiful Pleiades? Can you loose the cords of Orion?" (Job 38:31). The automaker Subaru's name is the Japanese word for the Pleiades, Rhee said.

The Pleiades is probably the best known star cluster and the most striking to the naked eye. "You've seen it many times, and it's now easily visible in the evening sky," said research co-author Benjamin Zuckerman, UCLA professor of physics and astronomy.

Although referred to as the "seven sisters," "the cluster actually contains some 1,400 stars," said co-author Inseok Song, a staff scientist at NASA's Spitzer Science Center at the California Institute of Technology and a former astronomer with the Gemini Observatory.

Located about 400 light-years away, the Pleiades is one of the closest star clusters to Earth. One of the cluster's stars, known as HD 23514, which has a mass and luminosity a bit greater than those of the sun, is surrounded by an extraordinary number of hot dust particles — "hundreds of thousands of times as much dust as around our sun," Zuckerman said. "The dust must be the debris from a monster collision, a cosmic catastrophe."

The astronomers analyzed emissions from countless microscopic dust particles and concluded that the most likely explanation is that the particles are debris from the violent collision of planets or planetary embryos.

Song calls the dust particles the "building blocks of planets," which can accumulate into comets and small asteroid-size bodies and then clump together to form planetary embryos, eventually becoming full-fledged planets.

"In the process of creating rocky, terrestrial planets, some objects collide and grow into planets, while others shatter into dust," Song said. "We are seeing that dust."

HD 23514 is the second star around which Song and Zuckerman recently have found evidence of terrestrial planet formation. They and their colleagues reported in the journal Nature in July 2005 that a sun-like star known as BD +20 307, located 300 light-years from Earth in the constellation Aries, is surrounded by one million times more dust than is orbiting our sun.

In an effort to uncover comparably dusty stars after their 2005 research, Rhee, Song and Zuckerman began looking through thousands of publicly accessible, deep-infrared images obtained by the Spitzer Space Telescope and soon discovered HD 23514. The astronomers then used the Gemini North telescope, located on Hawaii's dormant volcano Mauna Kea, to measure the heat radiation coming from the dust; the heat emerges at infrared wavelengths, just as the heat from our bodies does, Song said.

"The Gemini and Spitzer data were crucial in identifying and establishing the amount and location of dust around the star," Song said.

While our sun is 4.5 billion years old, the Pleiades Aries stars are "adolescents," about 100 million and 400 million years old, respectively, Rhee said. Based on the age of the two stars and the dynamics of the orbiting dust particles, the astronomers deduce that most adolescent sun-like stars are likely to be building terrestrial-like planets through recurring violent collisions of massive objects. The cosmic debris from only a small percentage of such collisions can be seen at any one time — currently, only HD 23514 and BD +20 307 have visible debris.

"Our observations indicate that terrestrial planets similar to those in our solar system are probably quite common," Zuckerman said.

The astronomers calculate that terrestrial planets or planetary embryos in the Pleiades collided within the last few hundred thousand years — or perhaps much more recently — but they cannot rule out the possibility that multiple, somewhat smaller collisions occurred.

Many astronomers believe our moon was formed through the collision of two planetary embryos — the young Earth and a body about the size of Mars. That crash created tremendous debris, some of which condensed to form the moon and some of which went into orbit around the young sun, Zuckerman said.

By contrast, the collision of an asteroid with Earth 65 million years ago, the most favored explanation for the final demise of the dinosaurs, was a mere pipsqueak, he said.

"Collisions between comets or asteroids wouldn't produce anywhere near the amount of dust we are seeing," Song said.

HD 23514 and BD +20 307 are by far the dustiest not-so-young stars in the sky. "Nothing else is even close," Song said.

Very young stars — those 10 million years old or younger — may have a similar amount of dust around them as a result of the star-formation process. However, by the time a star is 100 million years old, this "primordial" dust has dissipated because the dust particles get blown away or dragged onto the star, or the particles clump together to form much larger objects.

"Unusually massive amounts of dust, as seen at the Pleiades and Aries stars, cannot be primordial but rather must be the second-generation debris generated by collisions of large objects," Song said.

The Pleiades have been considered important by many cultures throughout history.

"To the Vikings, the Pleiades was Freyja's hens," Rhee said. In Bronze Age Europe, the Celts and others associated the Pleiades with mourning and funerals because the cluster rose in the eastern night sky between the autumnal equinox and the winter solstice, which was a festival devoted to the remembrance of the dead. The ancient Aztecs of Mexico and Central America based their calendar on the Pleiades.

The astronomers' research results are based on mid- and far- infrared observations made with the Gemini 8-meter Frederick C. Gillett Telescope at Gemini North and the space-based infrared observatories Infrared Astronomical Satellite (IRAS), Infrared Space Observatory (ISO) and NASA's Spitzer Space Telescope.

The Gemini Observatory is an international collaboration utilizing two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located at Mauna Kea, Hawaii (Gemini North); the other is at Cerro Pachón in central Chile (Gemini South). Together they provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

UCLA is California's largest university, with an enrollment of nearly 37,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer more than 300 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Four alumni and five faculty have been awarded the Nobel Prize.

Source: UCLA press release

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#128    Waspie_Dwarf

Waspie_Dwarf

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Posted 16 November 2007 - 06:10 PM

Astronomers Spot Evidence for Colliding Planet Embryos in Famous Star Cluster

The Gemini Observatory press release is reproduced below:

Wednesday, 14 November 2007

Press Release
UCLA / Gemini Observatory

Contacts:

Peter Michaud
Gemini Observatory, Hilo HI, USA
(808) 974-2510 (desk)
(808) 937-0845 (cell)
pmichaud@gemini.edu

Stuart Wolpert
UCLA
Desk: (310) 206-0511
swolpert@support.ucla.edu

Astronomers have found evidence for the formation of young rocky planets around the star HD 23514 located in the well-known Pleiades (Seven Sisters) star cluster that is easily visible in the current evening sky.

Using an infrared sensitive camera (MICHELLE) on the Gemini North Telescope, Joseph Rhee of UCLA and his collaborators have measured heat from hot dust surrounding a 100 million year old star in the bright star cluster. The star has properties very much like our Sun except that it is 45 times younger and is orbited by hundreds of thousands of times more dust than our Sun. The star is also one of the very few solar-type stars known to be orbited by warm dust particles.

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Gemini Observatory/Lynette Cook
Figure 1: Artist's rendering of what the environment around HD 23514 might look like as two Earth-sized bodies collide. Artwork by Lynette Cook for Gemini Observatory.

These warm emissions betray catastrophic collisions in an evolving young planetary system around an adolescent-age solar type star. The emission appears to originate from dust located in the terrestrial planet zone between about 1/4 to two astronomical units (AUs) from the parent star HD 23514, a region corresponding to the orbits of Mercury and Mars in our solar system.

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Credit: Inseok Song/Digital Sky Survey, inset: Gemini Observatory/Lynette Cook
Figure 2: Color composite image of the Pleiades star cluster and surrounding region produced by Inseok Song of the Spitzer Science Center. The image was created by combining B, R and I band images from individual second generation Digital Sky Survey images into blue, green and red image layers, respectively. The location of HD 23514 is shown by the yellow arrow. Inset artwork (lower right) is same as in Figure 1.

Rhee and team members Inseok Song of the Spitzer Science Center and Benjamin Zuckerman of UCLA interpret the presence of so much hot dust as a result of colliding planetary embryos leading to the conclusion that a recent collision occurred between relatively large rocky bodies. According to Zuckerman, this is thought to be similar to the encounter that produced the Earth-Moon system more than four billions ago. "Indeed, the collision that generated the Moon sent a comparable mass of debris into interplanetary orbits as is now observed in HD 23514," said Zuckerman.

The astronomers analyzing the emission from countless microscopic dust particles propose that the most likely explanation is they were pulverized in the violent collision of planets or “planetary embryos.” Song calls the dust particles the “building blocks of planets,” which accumulate into comets and small asteroid-size bodies, and then clump together to form planetary embryos, and finally full-fledged planets. “In the process of creating rocky, terrestrial planets, some objects collide and grow into planets, while others shatter into dust; we are seeing that dust,” Song said.

These new observations indicate that rocky terrestrial planets, perhaps like the Earth, Mars or Venus, appear to be forming or to have recently formed. “This is the first clear evidence for planet formation in the Pleiades, and the results we are presenting strongly suggest that terrestrial planets like those in our solar system are quite common,” said Joseph Rhee, UCLA postdoctoral scholar in astronomy, and lead author of the research.

Astronomers report the findings in an upcoming issue of the Astrophysical Journal, published by the American Astronomical Society.

The Pleiades star cluster, in the constellation of Taurus, is easily visible to the naked eye at this time of the year. The cluster is well-known in many cultures, and is cited in the Bible, noted Rhee: “Can you bind the beautiful Pleiades? Can you loose the cords of Orion?” ( Job 38:31).

Although referred to as the seven sisters, “the cluster actually contains some 1,400 stars,” said Inseok Song, a staff scientist at Caltech’s Spitzer Science Center, former astronomer with the Gemini Observatory, and a co-author of the research. Located about 400 light years away, the Pleiades is one of the closest star clusters to Earth.

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Figure 3: Spectral energy distribution of the dusty 100 million year old solar-type star HD 23514 in the Pleiades star cluster. The unusual mid-infrared excess is most noticeable in the thermal infrared region. There is also a strong silicate feature around 9 microns

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Figure 4: MICHELLE mid-infrared spectrum of HD 23514 obtained on the Gemini North telescope. For comparison, the mid-infrared, (dotted-line) spectrum of another dusty star BD +20 307 is also reproduced. Both reveal the presence of warm dust. HD 23514 has the warmer dust, reflected by its more "blue shifted" bump. For young stars and debris disks, the most prominent spectral feature in the N-band is silicate emission

Background
  • The research team used the Gemini North telescope on Mauna Kea on the island of Hawaii to measure the heat radiation coming from the dust; “this heat emerges at infrared wavelengths, just as the heat from our bodies does,” Song said. “The Gemini data were crucial” in establishing the amount and location of dust around the star, he said.

  • The Pleiades star (HD 23514) is the second star around which Song and Zuckerman have recently found evidence of terrestrial planet formation. They and colleagues reported in the journal Nature in July 2005 that a sun-like star, known as BD+20 307, located 300 light-years from Earth in the direction of the constellation Aries, is surrounded by a shocking one million times more dust than is orbiting around our sun. According to Zuckerman HD 23514, “…has hundreds of thousands of time as much dust as around our sun.”

  • While the sun is 4.5 billion years old, both HD 23514 and BD+20-307 are “adolescents,” about 100 million and 400 million years old, respectively, Rhee said. Based on the age of the two stars and the dynamics of the orbiting dust particles, the astronomers deduce that most adolescent-age sun-like stars are likely to be building terrestrial-like planets via recurring violent collisions of massive objects, but the cosmic debris from only a small percentage can be seen at any one time — currently, only stars HD23514 and BD+20 307 are known.

  • HD23514 and BD+20 307 are by far the dustiest not-so-young stars in the sky, Song said; “nothing else is even close.” Very young stars, 10 million years old or younger, may have this much dust around them, as a remnant of the star formation process. However, by the time a star is 100 million years old, the dust has dissipated because the dust particles get blown away or dragged onto the star, or the particles clump together to form much larger objects.

  • In parts of Polynesia and Hawai‘i, the Pleiades were used to help determine the start of the new year (the New Year celebration is called Makahiki in Hawaii). In Hawai‘i the cluster is known as Makali‘i.

  • “In Greek mythology, the Pleiades represented Seven Sisters; to the Vikings, the Pleiades was Freyja's hens,” Rhee said. In Bronze Age Europe, the Celts and others associated the Pleiades with mourning and funerals because the cluster rose in the eastern night sky between the autumn equinox and the winter solstice, which was a festival devoted to the remembrance of the dead. The ancient Aztecs of Mexico and Central America based their calendar upon the Pleiades.

  • The results are based on mid- and far- infrared observations made with the Gemini 8-meter Frederick C. Gillett Telescope (Gemini North) and space-based infrared observatories: Infrared Astronomical Satellite (IRAS), Infrared Space Observatory (ISO), and Spitzer Space Telescope.

  • The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located at Mauna Kea, Hawai'i (Gemini North) and the other telescope at Cerro Pachón in central Chile (Gemini South), and hence provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

  • UCLA is California’s largest university, with an enrollment of nearly 37,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university’s 11 professional schools feature renowned faculty and offer more than 300 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Four alumni and five faculty have been awarded the Nobel Prize.


Source: Gemini Observatory press release

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#129    Waspie_Dwarf

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Posted 24 November 2007 - 02:46 AM

Probing the nurseries of miniature planetary systems

The University of St Andrews press release is reproduced below:

20 November 2007

New research led by a University of St Andrews astronomer has found evidence for what might be the raw material for the beginning of shrunken versions of our solar system -  miniature worlds in the making.

In their study Dr Alexander Scholz, SUPA Advanced Fellow at the University of St Andrews, and Professor Ray Jayawardhana, from the University of Toronto, challenge the assumption that other planetary systems in the Universe would necessarily look like our own solar system.

The astronomers have found that the birthplaces of planets exist not only around young stars but also around planemos (short for planetary mass objects) that are not much larger or heavier than Jupiter. This may imply the existence of miniature solar systems with a central object having only about 1% of the mass of the Sun.

Since their discovery in 2000, the nature and origin of the enigmatic planemos has been a hot topic - are they tiny stars or giant planets, kicked out from a young planetary system? The new study now suggests that the former scenario is much more likely.

In a paper to be published in the Astrophysical Journal (Letters) Dr Scholz and Professor Jayawardhana used the Spitzer Space Telescope to observe 18 planemos in a star cluster in Orion that is about 3 million years old. At that age many young stars are still surrounded by disks of dust and gas which may evolve into planetary systems. The dust in these disks 'glows' in the infrared wavelength range and can therefore be seen with infrared cameras.

The new observations show that about one third of the planemos are also surrounded by dusty disks, thus these relatively small objects seem to have a star-like infancy.  

Evidence for a star-like formation of planemos has been presented previously by other teams but the new observations constitute the first systematic survey and push our knowledge of planemos into new territory.

"The results demonstrate that long-lived dusty disks, the nurseries of planets, are commonly found even around extremely low-mass objects. This could indicate that planetary systems may form even when the central 'star' is not a star, but a planemo.

Imagine a solar system where planets encircle an object which itself is not much larger than a planet," explains Dr Scholz.

Although the new findings have not settled the origins of planemos Dr Scholz and Professor Jayawardhana believe the results bring us one step closer.

"How puny an object could nature produce in the same way that it made our Sun? That's the big question motivating our research. The answer will tell us a lot about the star formation process as well as about the true diversity of planetary systems out there," said Professor Jayawardhana.

Note:

SUPA (Scottish Universities Physics Alliance) is a research collaboration between St Andrews, Edinburgh, Heriot Watt, Paisley, Strathclyde and Glasgow Universities.

This project has been supported by SUPA and an NSERC (National Science and Engineering Research Council of Canada) grant to Professor Jayawardhana.The research project was based on observations using the Spitzer Space Telescope, a NASA mission managed by the Jet Propulsion Laboratory, with support from the Californian Institute of Technology.

The paper, accepted by the Astrophysical Journal (Letters) is available at http://arxiv.org/abs/0711.2510

Issued by the University of St Andrews - reference: Planemos/201107

Source: University of St Andrews Press Release

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#130    Waspie_Dwarf

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Posted 28 November 2007 - 11:19 PM

Youthful Star Sprouts Planets Early


linked-image
An artist concept of UX Tau A
NASA/JPL-Caltech/T. Pyle (SSC)


Written by Linda Vu, Spitzer Science Center
November 28, 2007


A stellar prodigy has been spotted about 450 light-years away in a system called UX Tau A by NASA's Spitzer Space Telescope. Astronomers suspect this system's central Sun-like star, which is just one million years old, may already be surrounded by young planets. Scientists hope the finding will provide insight into when planets began to form in our own solar system.

"This result is exciting because we see a gap, potentially carved out by planets, around a dusty Sun-like star. In almost all other star systems of this age, we typically see a primordial disk -- a thick disk of dust, without any clearings," said Catherine Espaillat, a graduate student at the University of Michigan, Ann Arbor.

Prior to the Spitzer observations, Espaillat and her teammates knew that a Sun-like star sat at the center of UX Tau A. Now, using the telescope's infrared spectrometer instrument, they have discerned details about the dusty disk swirling around the central star.

Such dusty disks are where planets are thought to be born. Dust grains clump together like snowballs to form larger rocks, and then the bigger rocks collide to form the cores of planets. When rocks revolve around their central star, they act like cosmic vacuum cleaners, picking up all the gas and dust in their path and creating gaps.

Spitzer saw a gap in UX Tau A's disk that extends from 0.2 to 56 astronomical units (an astronomical unit is the distance between the sun and Earth). In our solar system, this gap would occupy the space between Mercury and Saturn. Espaillat notes that the formation of one or more planets could be responsible for carving out the gap.

Although gaps have been detected in disks swirling around young stars before, Espaillat notes that UX Tau A is special because the gap is sandwiched between two thick disks of dust. An inner thick dusty disk hugs the central star, then, moving outward, there is a gap, followed by another thick doughnut-shaped disk. Other systems with gaps contain very little to no dust near the central star. In other words, those gaps are more like big holes in the centers of disks.

Some scientists suspect that the holes could have been carved out by a process called photoevaporation. Photoevaporation occurs when radiation from the central star heats up the gas and dust around it to the point where it evaporates away. The fact that there is thick disk swirling extremely close to UX Tau A's central star rules out the photoevaporation scenario. If photoevaporation from the star played a role, then large amounts of dust would not be floating so close to the star.

"This finding definitely affects the way astronomers look at planet formation. Spitzer's infrared spectrometer was able to see a gap in this system, but future, more sensitive telescopes maybe able to search for Earth-like planets in UX Tau A," said Espaillat.

Her paper will be published in the December 2007 issue of Astrophysical Journal Letters. Other authors on the paper include Nuria Calvet, Jesus Hernández and Lee Hartmann, also from the University of Michigan; Paola D'Alessio of the Universidad Nacional Autónoma de México, Michoacán; Chunhua Qi of the Harvard-Smithsonian Institute for Astrophysics, Cambridge, Mass.; Elise Furlan of the NASA Astrobiology Institute at the University of California at Los Angeles; and Dan Watson of the University of Rochester, N.Y.

Previous results from Calvet and Watson are online at _http://www.spitzer.caltech.edu/features/articles/20050912.shtml.

Source: NASA/CalTech - Spitzer- Newsroom

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#131    Waspie_Dwarf

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Posted 28 November 2007 - 11:25 PM

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NASA/JPL-Caltech/T. Pyle (SSC)


UX Tau A

This is an artist's rendition of the one-million-year-old star system called UX Tau A, located approximately 450 light-years away.

Observations from NASA's Spitzer Space Telescope showed a gap in the dusty planet-forming disk swirling around the system's central Sun-like star. The gap extends from the equivalent of Mercury to Saturn in our solar system, and is sandwiched between thick inner and outer disks on either side. Astronomers suspect that the gap was carved out by one or more forming planets.

Source: NASA/CalTech - Spitzer- Newsroom

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#132    Waspie_Dwarf

Waspie_Dwarf

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Posted 30 November 2007 - 01:00 AM

Instrument to Unveil New Worlds by Blocking Out Starlight

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Above: The Lyot Project will be installed at Palomar Observatory, where adaptive optics systems are used to obtain sharper images such as this infrared view of the star Gliese 105 (inset).

Ben Oppenheimer calls starlight "the bane of planet hunting."

Although more than 250 planets are known to orbit other stars, so far no one has been able to get a good look at any of them. That's largely because a star's glare is millions of times brighter than a planet, so trying to see a planet next to a star is akin to trying to spot a firefly next to a spotlight, from thousands of miles away. But it's a problem Oppenheimer and his colleagues at the American Museum of Natural History in New York hope to solve with a new instrument called the Lyot Project.

"I think we are very close to having a picture of an exoplanet - maybe even within two years ... it's a race," he said.

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Above: These two images simulate
the performance of the Lyot coronagraph.
It works by blocking light from a star so
that the planets orbiting it can be more
clearly seen.


At the heart of the project is an advanced coronagraph, a type of instrument that can get better information about exoplanets by directly blocking the light from the stars they orbit - similar to shielding your eyes from the sun on a bright day. "It's like an artificial eclipse," Oppenheimer said. The hope is that the instrument eventually will be able to block out enough of a star's light that astronomers can snap pictures of exoplanets - and maybe even discover another Earthlike world.

Playing Tricks with Light

The coronagraph itself is a four-foot square piece of breadboard studded with mirrors and light-collecting instruments. Starlight gathered by a telescope is bounced by mirrors into the coronagraph, which focuses the image, then sends the light past what is called an occulting spot. This dark spot blocks out the light from the central portion of the star image, similar to holding your thumb up to the setting sun. Another light-blocking stage, called the Lyot stop, removes most of the remaining rings of light from the star. The result is an image that contains only 1.5 percent of the light from the star, making it much easier to pick out the faint planets that orbit it.

For the first three years of its existence, the Lyot instrument was located at an Air Force Telescope in Maui, Hawaii, the US Air Force AEOS (Advanced Electro Optical System). This telescope proved a good testing ground for the coronagraph and the team is just beginning to publish their findings from that period. Now the coronagraph is back in Oppenheimer's New York lab, where it's being retrofitted for installation at the Palomar Observatory in California, near San Diego.

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Above: Ben Oppenheimer, the principal investigator
of the Lyot Project, makes adjustments to the coronagraph
on a work bench.


Palomar's 200-inch Hale Telescope was an obvious choice, Oppenheimer said, because it is undergoing improvements that will give it the highest level of correction of any Earth-bound telescope. "We're trying to push the technology forward Ö trying new technology on real telescopes, where reality is different than it is in the lab," he said.

The telescope has 249 actuators - tiny deformable mirrors that work to smooth out light that has been distorted by the atmosphere and gravity in space. In 2010, that number will be upgraded to 3,000, giving Palomar the ability to observe incredibly precise images. That accuracy is vitally important to planet hunters like Oppenheimer as they try to pick out very faint planets many light-years away.

The Lyot team plans to have the coronagraph installed in Palomar by next summer, and the project will be in full swing when the telescope's optics are upgraded two years later.

Going to Extremes

Meanwhile, at NASA's Jet Propulsion Laboratory in Pasadena, California, another group of researchers has begun work on a project that will help make the Lyot Project's findings even more accurate. The Post Coronagraph Wavefront Sensor is an instrument that will receive the light that has already passed through the coronagraph. The calibration system will analyze this image for flaws and pass the information back to the adaptive optical system that first receives the starlight, allowing it to further correct the image.

"This device sharpens the images, takes out speckles and fine-tunes it," said Mike Shao, a JPL engineer who is heading up the project. "We just started work on it a few weeks ago and we hope to install it in two years." Shao explains that while correction systems like those he is working on have been used before, his current project should be "three orders of magnitude more powerful than the previous generation." and is one of the first sensors of its kind to be used with light that's already passed through a coronagraph.

linked-image
Above: Palomar Observatory, California, houses some
of the most advanced telescopes in the world and is the
future home of the Lyot Project.


The information that Shao, Oppenheimer and the rest of those working on the Lyot Project hope to uncover will be invaluable to astronomers who want to know how our solar system fits into the big picture. Oppenheimer stresses that that until now, Earth's solar system had been our only model for how other planetary systems work. He compares it to the study of music. "If you just listened to Elvis, you wouldn't be able to predict the existence of classical music or rap," Oppenheimer said. "We're laying the technical groundwork for us to be able answer compelling, fundamental questions."

Oppenheimer predicts that the field of exoplanet observation will progress quickly as projects like Lyot push the technological envelope. As for the discovery of an Earth-like planet, he predicts that it's also not that far off. And he's optimistic about the effect such a discovery will have on our perception of the universe.

"People have a tendency to think of themselves as the center of the universe," he muses. "But planets are very plentiful - they may outnumber the stars. I hope [the discovery of an Earth-like planet] would influence our consciousness at large when it happens."

For more information about NASA's search for new worlds, visit the PlanetQuest Web site at _http://planetquest.jpl.nasa.gov.

Joshua Rodriguez/PlanetQuest

Source: NASA - Exploring the Universe - New Worlds

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#133    Waspie_Dwarf

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Posted 12 December 2007 - 07:35 PM

heic0720: Hazy red sunset on extrasolar planet

The ESA press release is reproduce below:

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11-Dec-2007: The NASA/ESA Hubble Space Telescope has given astronomers a fascinating new insight into the atmosphere of a planet in orbit around another star. The observations provide evidence of the presence of hazes in the atmosphere of the planet HD 189733b.

A team of astronomers have used the NASA/ESA Hubble Space Telescope to detect, for the first time, strong evidence of hazes in the atmosphere of a planet orbiting a distant star. The discovery comes after extensive observations made recently with Hubble’s Advanced Camera for Surveys (ACS).

The team, led by Frédéric Pont from the Geneva University Observatory in Switzerland, used Hubble’s ACS to make the first detection of hazes in the atmosphere of the giant planet. "One of the long-term goals of studying extrasolar planets is to measure the atmosphere of an Earth-like planet, this present result is a step in this direction" says Pont. "HD 189733b is the first extrasolar planet for which we are piecing together a complete idea of what it really looks like."

The new observations were made as the extrasolar planet, dubbed HD 189733b, passed in front of its parent star in a transit. As the light from the star passes through the atmosphere around the limb of the giant extrasolar planet, the gases in the atmosphere stamp their unique signature on the starlight from HD 189733.

The planet itself, orbiting close to its parent star, is a ‘hot-Jupiter’ type of gas giant slightly larger than Jupiter. The proximity to its star results in an atmospheric temperature of roughly seven hundred degrees Celsius. Measurements of the way light varies as the planet passes in front of its parent star indicates that HD 189733b has neither Earth-sized moons nor any discernable Saturn-like ring system.

Hubble’s ACS camera, coupled with a grism (a kind of cross between a prism and a diffraction grating) allowed the astronomers to make extremely accurate measurements of the spectrum of HD 189733b, allowing conclusions to be drawn about the composition of the planet’s atmosphere. The exquisite level of precision needed to make this observation can only, at the moment, be achieved from space. The combination of a large planet and relatively small parent star – only 76% of the diameter of our Sun – contributes to the success of this delicate experiment.

Where the scientists had expected to see the fingerprints of sodium, potassium and water there were none. This finding, combined with the distinct shape of the planet’s spectrum, infers that high level hazes (with an altitude range of roughly 1000 km) are present. So the atmosphere on HD 189733b would look very similar to a gorgeous red sunset over Athens! Venus and Saturn’s moon Titan, in our own Solar System, are also covered with haze. According to the scientists the haze probably consists of tiny particles (less than 1/1000 mm in size) of condensates of iron, silicates and aluminium oxide dust (the compound on Earth which the mineral sapphire is made of).

As part of the observations of HD 189733, the teams of astronomers also needed to accurately account for the variations in the star’s brightness during the set of observations. ‘Starspots’ like those seen on our own Sun may cover several percent of the star and are thought to be about 1000 degrees Celsius cooler than the rest of HD 189733’s surface. It was found that there is a starspot on the star’s surface which is over 80,000 km across.

Notes:

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

The Space Telescope European Coordinating Facility in Garching near Munich, Germany is responsible for Hubble’s grism mode.

Image credit: ESA, NASA and Frédéric Pont (Geneva University Observatory)

Links:

Science paper
Spitzer Space Telescope release on July 11 2007
Spitzer Space Telescope release on February 21 2007
Spitzer Space Telescope release on February 21 2006

Contacts:

Frédéric Pont
Geneva University Observatory, Switzerland
Cellular: +41-78-623-9654
Email: Frederic.Pont@obs.unige.ch

Lars Lindberg Christensen
Hubble/ESA, Garching, Germany
Tel: +49-(0)89-3200-6306
Cellular: +49-(0)173-3872-621
E-mail: lars@eso.org

Ray Villard
Space Telescope Science Institute, Baltimore, USA
Tel: +1-410-338-4514
E-mail: villard@stsci.edu

Source: ESA - Hubble Space Telescope

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#134    Waspie_Dwarf

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Posted 12 December 2007 - 07:40 PM

Artist’s impression of the hazy red sunset on HD 189733b

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An artist’s impression of the extrasolar planet HD 189733b seen here with its parent star looming behind. The planet is slightly larger than our own Solar System’s Jupiter. Its atmosphere is a scorching eight hundred degrees Celsius. Astronomers have found that the sunset on HD 189733b would look similar to a hazy red sunset on Earth.

Credit: ESA, NASA and Frederic Pont (Geneva University Observatory)


Source: ESA - Hubble Space Telescope

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#135    Waspie_Dwarf

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Posted 12 December 2007 - 07:54 PM

Wide-field view of HD 189733b and surroundings (DSS2 excerpt)

linked-image

A star field image showing the star HD 189733 (centre). The NASA/ESA Hubble Space Telescope has given astronomers a fascinating new insight into the atmosphere of a HD 189733b. The observations provide clear evidence of the presence of hazes in its atmosphere. To the right of the star is the notable planetary nebula Messier 27. The field-of-view is approximately 0.9 x 0.6 degrees.

Credit: NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)


Source: ESA - Hubble Space Telescope


"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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