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Exoplanets - Planets Beyond Our Solar System


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#136    Waspie_Dwarf

Waspie_Dwarf

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Posted 12 December 2007 - 07:57 PM

Wide-field view of the Summer Triangle

linked-image

A wide field image of the region of sky in which HD 189733b is located. In this image we can see the asterism of the ‘Summer Triangle’ a giant triangle in the sky composed of the three bright stars Vega (top left), Altair (lower middle) and Deneb (far left). HD 189733b is orbiting a star very close to the centre of the triangle.

Credit: A. Fujii


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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#137    Waspie_Dwarf

Waspie_Dwarf

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Posted 12 December 2007 - 08:04 PM

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

linked-image

A wide star field image of the region around HD 189733b. In the centre is the star HD 189733 and just to the right is the planetary nebula Messier 27. The field-of-view is approximately 2.7 x 2.8 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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#138    Waspie_Dwarf

Waspie_Dwarf

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Posted 12 December 2007 - 08:12 PM

Hubble Finds that Extrasolar Planet Has a Hazy Sunset

December 11, 2007   10:00 AM (EDT)
News Release Number: STScI-2007-44

Artist's Concept of Extrasolar Planet's Hazy Atmosphere

linked-image

ABOUT THIS IMAGE:
A team of astronomers, led by Frederic Pont from the Geneva University Observatory in Switzerland, has detected for the first time strong evidence of hazes in the atmosphere of a planet orbiting a distant star. The new Hubble Space Telescope observations were made as the extrasolar planet, dubbed HD 189733b, passed in front of its parent star in an eclipse. As the light from the star briefly passes through the exoplanet's atmosphere, the gases in the atmosphere stamp their unique spectral fingerprints on the starlight. Where the scientists had expected to see the fingerprints of sodium and potassium, there were none; implying that high-level hazes (with an altitude of nearly 2,000 miles) are responsible for blocking the light from these elements. This is an artist's concept of HD 189733b and its parent star.

For additional information, contact:

Frederic Pont
Geneva University Observatory, Switzerland
frederic.pont@obs.unige.ch

Lars Lindberg Christensen
Hubble/ESA, Garching, Germany
011-49-89-3200-6306
lars@eso.org

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

Image Type: Artwork

Credit for Ground-based Image: F. Pont (Geneva University Observatory, Switzerland)

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

Source: HubbleSite - Newsdesk

"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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#139    Waspie_Dwarf

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Posted 05 January 2008 - 12:01 PM

A young extrasolar planet in its cosmic nursery

The Max Planck Institute for Astronomy press release is reproduced below:

Press Release 08-01-02

Astronomers from Heidelberg discover planet in a dusty disk around a newborn star


Scientists at the Max Planck Institute for Astronomy in Heidelberg have discovered the youngest known extrasolar planet. Its host star is still surrounded by the disk of gas and dust from which it was only recently born. This discovery allows scientists to draw important conclusions about the timing of planet formation.

How do planetary systems form? How common are they? What is their architecture? How many habitable earth-like planets exist in the Milky Way? In the past decade, astronomers have clearly come closer to finding answers to these exciting questions. With the discovery of the first planet orbiting another Sun-like star in 1995, the field of extrasolar planet research was born.

Today, almost 12 years later, more than 250 exoplanets have been discovered. A group of scientists at the Max Planck Institute for Astronomy in Heidelberg is also looking for these objects. A planet next to a bright star appears like a glow-worm next to a lighthouse. It is (not yet) possible to directly make images of most extrasolar planets. Therefore, astronomers often use an indirect detection method.

As a planet orbits its host star, it pulls the star in periodically alternating directions with its gravity. The star then sometimes moves a little towards us, and at other times away from us. When it moves towards us, the light waves are “compressed” which is equivalent to the light becoming bluer. When the star moves away, the waves are “stretched” and the light is “red-shifted”. The periodic change of color, or shift of spectral lines, known as the “Doppler effect”, can thus reveal an unseen planet and allows astronomers to derive a lower limit to its mass. So far this so called “radial velocity” method remains the most successful technique in detecting exoplanets. However, no planet has ever been found around a new-born Sun-like star. The detection of young planets would provide the most important key to understanding questions like: how and where do planets form, and what timescales are involved in this process?

With this in mind, a team of astronomers from the Max Planck Institute for Astronomy (MPIA) in Heidelberg (Germany) has monitored radial velocity variations of about 200 young stars to search for extrasolar planets. One of these was the nearby star TW Hydrae, which is only 8-10 million years old (about 1/500th the age of our Sun). Like other stars at this young age, it is still surrounded by a circumstellar disk of gas and dust, believed to be the birthplace of planets.

The team has now discovered a planetary companion that orbits the young star TW Hydrae within an inner hole in its disk (Figure 1). “When we monitored the radial velocity of TW Hydrae, we detected a periodic variation that could not arise from stellar activity and pointed towards the presence of a planet” (Figure 2) said Johny Setiawan (MPIA), the leader of the observational program. The detection was made with the FEROS spectrograph at the 2.2m telescope belonging to the Max Planck Society and the European Southern Observatory (ESO) at La Silla in Chile.

The newly-discovered planet, called TW Hydrae b, is a heavyweight; it is about ten times as massive as Jupiter, the biggest planet in our Solar System. The planet orbits its host star in only 3.56 days at a distance of about 6 million kilometres (Figure 3). This corresponds to 4 percent of the distance from the Sun to the Earth.

Stellar activity represents a critical problem for the detection of extrasolar planets – in particular when the star is young and its surface is still very unstable. For example, when starspots (like those on our Sun) are large, they can mimic radial velocity variations caused by an orbiting planet. “To exclude any misinterpretation of our data, we have investigated all activity indicators of TW Hydrae in detail. But their characteristics are significantly different from those of the main radial velocity variation. They are less regular and have shorter periods,” said Ralf Launhardt (MPIA), who coordinates several search programs for extrasolar planets around young stars.

Planets form from dust and gas in a circumstellar disk shortly after the birth of a star. Not all aspects of this process are yet understood. However, the discovery of TW Hydrae b provides new constraints on planet formation theories. Based on statistical studies, astronomers have estimated the average lifetime of a circumstellar disk to be 10 – 30 million years. This would then be the maximum time available to form planets in a disk. The detection of TW Hydrae b now provides the first direct measurement of a true upper limit of the formation time of a giant planet: it cannot be older than its host star, i.e., 8 – 10 million years. “This is one of the most exciting discoveries in the study of extrasolar planets,” said Thomas Henning, the director of the Planet and Star Formation Department at MPIA. “For the first time, we have directly proven that planets indeed form in circumstellar disks. The discovery of TW Hydrae b opens the way to linking the evolution of circumstellar disks with the processes of planet formation and migration.” It is the ideal system to test numerical models of planet formation.

Scientists at the Max Planck Institute for Astronomy are currently developing next-generation instruments to detect extrasolar planets with other techniques, such as direct imaging, measuring the tiny reflex motion of a star in the plane of the sky (astrometry), or the dimming effect when a planet moves in front of the star (transit photometry). In the near future, these instruments will open the door to finding other extrasolar planets that cannot be detected by the radial velocity method. We will get a better understanding of planet formation when we understand the diversity of the planetary systems. We will then be able to place our own Solar System in a universal context. Finally, perhaps in the future we will be able to answer the question: “Are we alone in the Universe?”

linked-image
Figure 1: The newly discovered giant planet orbits around its young and active host star inside the inner hole
of a dusty circumstellar disk (artist view).
Picture: Max Planck Institute for Astronomy



--------------------------------------------------------------------------------

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Figure 2: The diagram shows the variatios of the radial velocity of TW Hydrae as observed in early 2007. The
data can best be described as an oscillation with a period of 3.6 days, caused by a giant planet orbiting around the
star.
Picture: Max Planck Institute for Astronomy


--------------------------------------------------------------------------------


Original publication:
J. Setiawan, Th. Henning, R. Launhardt, A. Müller, P. Weise, M. Kürster
A young massive Planet in a star-disk system
Nature, 2. Januar 2008


Contact:
Dr. Johny Setiawan
Max-Planck-Institut für Astronomie,
Heidelberg
Tel. + 49 6221 528-326
Fax: + 49 6221 528-246
E-Mail: setiawan@mpia.de


--------------------------------------------------------------------------------
Dr. Ralf Launhardt
Max-Planck-Institut für Astronomie,
Heidelberg
Tel.: + 49 6221 528-207
Fax: + 49 6221 528-246
E-Mail: rlau@mpia.de


--------------------------------------------------------------------------------
Dr. Jakob Staude (Pressestelle)
Max-Planck-Institut für Astronomie,
Heidelberg
Tel.: +49 6221 528-229
Fax: + 49 6221 528-379
E-Mail: staude@mpia.de


Source: Max Planck Institute for Astronomy

"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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#140    Waspie_Dwarf

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Posted 05 January 2008 - 12:26 PM

Red Dust in Planet-Forming Disk May Harbor Precursors to Life

The Carnegie Institution press release is reproduced below:

Thursday, January 3, 2008
Washington, DC— Astronomers at the Carnegie Institution have found the first indications of highly complex organic molecules in the disk of red dust surrounding a distant star. The eight-million-year-old star, known as HR 4796A, is inferred to be in the late stages of planet formation, suggesting that the basic building blocks of life may be common in planetary systems.

linked-image
Planetary disk of HR 4796A

In a study published in the current Astrophysical Journal Letters, John Debes and Alycia Weinberger of the Carnegie Institution’s Department of Terrestrial Magnetism with Glenn Schneider of the University of Arizona report observations of infrared light from HR 4796A using the Near-Infrared Multi-Object Spectrometer aboard the Hubble Space Telescope. The researchers found that the spectrum of visible and infrared light scattered by the star’s dust disk looks very red, the color produced by large organic carbon molecules called tholins. The spectrum does not match those of other red substances, such as iron oxide.

Tholins do not form naturally on present-day Earth because oxygen in the atmosphere would quickly destroy them, but they are hypothesized to have existed on the primitive Earth billions of years ago and may have been precursors to the biomolecules that make up living organisms. Tholins have been detected elsewhere in the solar system, such as in comets and on Saturn’s moon Titan, where they give the atmosphere a red tinge. This study is the first report of tholins outside the solar system.

“Until recently it’s been hard to know what makes up the dust in a disk from scattered light, so to find tholins this way represents a great leap in our understanding,” says Debes.

HR 4796A is located in the constellation Centaurus, visible primarily form the southern hemisphere. It is about 220 light years from Earth. The discovery of its dust disk in 1991generated excitement among astronomers, who consider it a prime example of a planetary system caught in the act of formation. The dust is generated by collisions of small bodies, perhaps similar to the comets or asteroids in our solar system, and which may be coated by the organics. These planetesimals can deliver these building blocks for life to any planets that may also be circling the star.

“Astronomers are just beginning to look for planets around stars much different from the Sun. HR 4796A is twice as massive, nearly twice as hot as the sun, and twenty times more luminous than the Sun,” says Debes. “Studying this system provides new clues to understanding the different conditions under which planets form and, perhaps, life can evolve.”

This research is based on observations with the NASA/ESA Hubble Space Telescope and was supported by NASA and the NASA Astrobiology Institute.

Image Caption: Red and near infrared wavelengths from the dust disk surrounding the star HR 4796A (masked in false-color image to make fainter disk visible) suggest the presence of complex organic molecules. The inner “hole” of the ring-shaped disk is big enough to fit our entire solar system and may have been swept clean of dust by orbiting planets. (Image: John Debes)


Source: Carnegie Institution 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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#141    Waspie_Dwarf

Waspie_Dwarf

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Posted 11 January 2008 - 11:50 PM

When Worlds Collide:
Have Astronomers Observed the Aftermath of a Distant Planetary Collision?

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

Release No.: 2008-01

For Release: Wednesday, January 09, 2008 11:00:00 AM EST


Austin, TX - Astronomers announced today that a mystery object orbiting a star 170 light-years from Earth might have formed from the collision and merger of two protoplanets. The object, known as 2M1207B, has puzzled astronomers since its discovery because it seems to fall outside the spectrum of physical possibility. Its temperature, luminosity, age, and location do not match up with any theory.
"This is a strange enough object that it needs a strange explanation," said Eric Mamajek of the Harvard-Smithsonian Center for Astrophysics (CfA).

The announcement was made in a press conference at the 211th meeting of the American Astronomical Society.

linked-image
Illustrated here in this artist's concept, astronomers may have observed the aftermath of a collision between two protoplanets, one Jupiter-sized and one Neptune-sized, in the system 2M1207.
Credit: David A. Aguilar (Harvard-Smithsonian CfA)


2M1207B orbits a 25-Jupiter-mass brown dwarf called 2M1207A seen in the direction of the constellation Centaurus. Computer models show that 2M1207A is very young, only about 8 million years old; therefore its companion should also be 8 million years old. At that age, it should have cooled to a temperature of less than 1300 degrees Fahrenheit (1000 Kelvin). However, observations show that 2M1207B is actually about 2400 degrees F (1600 K). The extra heat might be the result of a protoplanetary collision.

"Most, if not all, planets in our solar system were hit early in their history. A collision created Earth's moon and knocked Uranus on its side," explained Mamajek. "It's quite likely that major collisions happen in other young planetary systems, too."

Given its temperature, astronomers would expect a certain luminosity for 2M1207B, but it is 10 times fainter than expected. In 2006, astronomers suggested that it is obscured by a dusty, edge-on disk. Mamajek and his colleague, Michael Meyer of the University of Arizona, propose an alternative explanation: 2M1207B is small, only about the size of Saturn, and therefore has a smaller-than-expected surface area radiating energy.

They derive a radius of 31,000 miles (50,000 km) for 2M1207B, compared to 37,000 miles (60,000 km) for Saturn. Given typical densities for giant planets, this would give 2M1207B a mass about 80 times Earth (or one-fourth Jupiter). The only plausible way for such a small object to be so hot millions of years after it formed is if it suffered a recent, titanic collision that heated it.

The planets in our solar system assembled from dust, rock, and gas, gradually growing larger over millions of years. But sometimes, two planet-sized objects collided catastrophically. For example, the Moon formed when an object about half the size of Mars hit the proto-Earth. If planet formation works the same way in other star systems, then 2M1207B might be the product of a collision between a Saturn-sized gas giant and a planet about three times the size of Earth. The two smacked into each other and stuck, forming one larger world still boiling from the heat generated in the collision.

"The Earth was hit by something one-tenth its mass, and it's likely that other planets in our solar system were too, including Venus and Uranus," explained Meyer. "If that one-tenth scale holds in other planetary systems, then we could be seeing the aftermath of a collision between a 72 Earth-mass gas giant and an 8 Earth-mass planet, even though such collisions are very unlikely."

Mamajek also points out that the collision theory is reasonable from a timescale point of view. A 2400-degree, Saturn-sized object would radiate its heat away over about 100,000 years. If the system were billions of years old, it is unlikely that we would be looking at the right time, but since the system is young, the chances are much better that we would catch it shortly after the collision while the hot aftermath is still observable.

The collision hypothesis makes several predictions that astronomers can test. Chief among them is a low surface gravity (which depends on a planet's mass and radius). To check this prediction, astronomers will need to get a better spectrum of 2M1207B -- a challenge since it is very faint and very close to the brown dwarf 2M1207A. Others are checking the dusty disk theory by looking for signs of polarization in the light from 2M1207B. More answers should be forthcoming within a year or two.

Mamajek emphasized that while a planet collision may not be the correct explanation for the weirdness of 2M1207B, examples of colliding planets are likely to be found by the next generation of ground-based telescopes.

"Hot, post-collision planets might be a whole new class of objects we will see with the Giant Magellan Telescope."

"Even if we're wrong, I wouldn't be surprised if someone finds a clear-cut case in the next 10 years," Mamajek added.

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

"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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#142    Waspie_Dwarf

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Posted 11 January 2008 - 11:55 PM

Earth: A Borderline Planet for Life?

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

Release No.: 2008-02
For Release: Wednesday, January 09, 2008 11:00:00 AM EST


Austin, TX - Our planet is changing before our eyes, and as a result, many species are living on the edge. Yet Earth has been on the edge of habitability from the beginning. New work by astronomers at the Harvard-Smithsonian Center for Astrophysics shows that if Earth had been slightly smaller and less massive, it would not have plate tectonics - the forces that move continents and build mountains. And without plate tectonics, life might never have gained a foothold on our world.
"Plate tectonics are essential to life as we know it," said Diana Valencia of Harvard University. "Our calculations show that bigger is better when it comes to the habitability of rocky planets."

This research was the subject of a press conference at the 211th meeting of the American Astronomical Society.

linked-image
A super-Earth like the one in this artist's conception can grow twice as large as Earth with up to 10 times the mass. Super-Earths are likely to be more life-friendly than our world because they would be more geologically active.
Credit: David A. Aguilar (Harvard-Smithsonian CfA)


Plate tectonics involve the movement of huge chunks, or plates, of a planet's surface. Plates spread apart from each other, slide under one another, and even crash into each other, lifting gigantic mountain ranges like the Himalayas. Plate tectonics are powered by magma boiling beneath the surface, much like a bubbling pot of chocolate. The chocolate on top cools and forms a skin or crust, just as magma cools to form the planet's crust.

Plate tectonics are crucial to a planet's habitability because they enable complex chemistry and recycle substances like carbon dioxide, which acts as a thermostat and keeps Earth balmy. Carbon dioxide that was locked into rocks is released when those rocks melt, returning to the atmosphere from volcanoes and oceanic ridges.

"Recycling is important even on a planetary scale," Valencia explained.

Valencia and her colleagues, Richard O'Connell and Dimitar Sasselov (Harvard University), examined the extremes to determine whether plate tectonics would be more or less likely on different-sized rocky worlds. In particular, they studied so-called "super-Earths"-planets more than twice the size of Earth and up to 10 times as massive. (Any larger, and the planet would gather gas as it forms, becoming like Neptune or even Jupiter.)

The team found that super-Earths would be more geologically active than our planet, experiencing more vigorous plate tectonics due to thinner plates under more stress. Earth itself was found to be a borderline case, not surprisingly since the slightly smaller planet Venus is tectonically inactive.

"It might not be a coincidence that Earth is the largest rocky planet in our solar system, and also the only one with life," said Valencia.

Exoplanet searches have turned up five super-Earths already, although none have life-friendly temperatures. If super-Earths are as common as observations suggest, then it is inevitable that some will enjoy Earth-like orbits, making them excellent havens for life.

"There are not only more potentially habitable planets, but MANY more," stated Sasselov, who is director of the Harvard Origins of Life Initiative.

In fact, a super-Earth could prove to be a popular vacation destination to our far-future descendants. Volcanic "rings of fire" could span the globe while the equivalent of Yellowstone Park would bubble with hot springs and burst with hundreds of geysers. Even better, an Earth-like atmosphere would be possible, while the surface gravity would be up to three times that of Earth on the biggest super-Earths.

"If a human were to visit a super-Earth, they might experience a bit more back pain, but it would be worth it to visit such a great tourist spot," Sasselov suggested with a laugh.

He added that although a super-Earth would be twice the size of our home planet, it would have similar geography. Rapid plate tectonics would provide less time for mountains and ocean trenches to form before the surface was recycled, yielding mountains no taller and trenches no deeper than those on Earth. Even the weather might be comparable for a world in an Earth-like orbit.

"The landscape would be familiar. A super-Earth would feel very much like home," said Sasselov.

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

"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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#143    Waspie_Dwarf

Waspie_Dwarf

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Posted 12 January 2008 - 11:46 AM

UF-led search for new planets part of ambitious new sky survey

The University of Florida press release is reproduced below:

Thursday, January 10, 2008.

GAINESVILLE, Fla. — A University of Florida-led sky survey that may double the number of known planets outside the solar system is part of a major new survey program announced today at the American Astronomical Society’s annual meeting in Austin, Texas.

The Sloan Digital Sky Survey III, slated to begin mid-year and end in mid-2014, consists of four independent surveys operated by the survey’s consortium. One will probe the distant universe and seek to learn more about mysterious dark energy, while two of the surveys will map the Milky Way and examine origins of stars. The UF-led survey will seek to find giant planets orbiting nearby stars and uncover more about the conditions in which they form.

linked-image
Star Survey
Here is an artist’s rendition of planets orbiting a sun-like star. A University of Florida-led sky survey announced Jan. 10, 2008, may double the number of known planets outside the solar system. The survey, which will use a UF-developed interferometer to scour 11,000 stars for possible planets, is part of a major new initiative announced at the at the American Astronomical Society’s annual meeting in Austin, Texas. Other surveys in the initiative will seek to learn more about mysterious dark energy, map the Milky Way and examine the origins of stars.
(T. Riecken)


“What we’re undertaking here is the largest homogeneous survey of planets ever conducted,” said Jian Ge, a UF professor of astronomy and the project’s principal investigator. “We not only want to find more planets, we also want to try to understand the big picture of how and where they form and evolve over time.”

At the heart of the survey — known as MARVELS, short for Multi-object Apache Point Observatory Radial Velocity Exoplanet Large-area Survey – is a UF-designed and built instrument capable of simultaneously surveying as many as 120 stars for planets.

The plan is to use the instrument, which employs a specially designed interferometer, to scour some 11,000 stars for orbiting giant planets — more than three times the number of stars searched by all other telescopes to date. The instrument detects planet signals through measuring the gravitational pull of the planet on the star.

The search is expected to yield not only at least 150 planets, almost double today’s number, but also provide much better understanding of the conditions needed for planets to be present. That’s important for future planet searches, including searches for Earth-like planets, because it will help astronomers narrow their search among millions of stars for those most likely to yield fast or interesting results.

“Only through a systematic, homogeneous survey like this one can we begin to understand different planet populations and probe planet distributions among different type stars and environments,” Ge said. “Also, this survey will provide many signposts for other astronomers using the really big, really expensive telescopes to discover smaller mass planets, possibly Earth-like planets, and also find more systems like our solar system.”

In order to substantially boost the survey speed and sample over current planet surveys capable of single object observations, the MARVELS survey will simultaneously target 120 relatively faint stars. The faintness of the stars largely limits the survey’s sensitivity to giant planets, although the UF instrument has four times the light particle, or photon, collecting power than current single object planet hunting instruments at other telescopes.

The search is expected to begin in the fall, shortly after the instrument is completed and installed. Like the other surveys, the MARVELS survey will be conducted from the 2.5 meter SDSS telescope at Apache Point Observatory in New Mexico.

The Sloan Digital Sky Survey III is a continuation of two previous SDSS surveys in the past eight years. The new survey is expected to be funded in part with a $7 million grant from the Alfred P. Sloan Foundation, with the survey and its four component surveys representing a total investment of about $50 million.

UF’s MARVELS instrument has about $2.5 million in funding, including part of an $875,000 grant from the W.M. Keck Foundation for an earlier, prototype version called the W.M. Keck Exoplanet Tracker. The UF survey is also being funded by the National Science Foundation, NASA and UF. Once the instrument is up and running, UF is expected to receive an additional roughly $6 million in funding for building another survey instrument, operating the survey, and handling the survey data, Ge said.

Ge said an added benefit of UF’s participation in the project is that it will allow UF astronomers free and timely access to data from all of the surveys. “We have full access to all that data, which is a huge scientific resource,” he said.

Stan Dermott, chairman of the UF astronomy department, noted that UF is also a partner with Spain in the world’s largest telescope, the Gran Telescopio Canarias, expected to begin scientific observations this year.

“Over the next 10 years,” he said, “the combination of the SDSS telescope and the GTC telescope may offer UF a unique tool to investigate both giant and Earth-like planets.”
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Aaron Hoover, ahoover@ufl.edu, 352-392-0186
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Jian Ge, jge@astro.ufl.edu, 352-246-1398 (cell)

Source: UF 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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#144    Mademoiselle

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Posted 18 February 2008 - 01:10 AM

http://news.bbc.co.uk/2/hi/science/nature/7249884.stm

"Rocky planets, possibly with conditions suitable for life, may be more common than previously thought in our galaxy, a study has found.

New evidence suggests more than half the Sun-like stars in the Milky Way could have similar planetary systems.

There may also be hundreds of undiscovered worlds in outer parts of our Solar System, astronomers believe.

Future studies of such worlds will radically alter our understanding of how planets are formed, they say.

New findings about planets were presented at the American Association for the Advancement of Science (AAAS) in Boston.

Nasa telescope

Michael Meyer, an astronomer from the University of Arizona, said he believes Earth-like planets are probably very common around Sun-like stars.

"Our observations suggest that between 20% and 60% of Sun-like stars have evidence for the formation of rocky planets not unlike the processes we think led to planet Earth," he said.

"That is very exciting."

Mr Meyer's team used the US space agency's Spitzer space telescope to look at groups of stars with masses similar to the Sun.

They detected discs of cosmic dust around stars in some of the youngest groups surveyed.

The dust is believed to be a by-product of rocky debris colliding and merging to form planets.

Nasa's Kepler mission to search for Earth-sized and smaller planets, due to be launched next year, is expected to reveal more clues about these distant undiscovered worlds.

Frozen worlds

Some astronomers believe there may be hundreds of small rocky bodies in the outer edges of our own Solar System, and perhaps even a handful of frozen Earth-sized worlds.

Speaking at the AAAS, Nasa's Alan Stern said he believes we have found only the tip of the iceberg in terms of planets within our own Solar System.

More than a thousand objects had already been discovered in the Kuiper belt alone, he said, many rivalling the planet Pluto in size.

"Our old view, that the Solar System had nine planets will be supplanted by a view that there are hundreds if not thousands of planets in our Solar System," he told BBC News.

He believes many of these planets will be icy, some will be rocky, and there may even be objects the same mass as Earth.

"It could be that there are objects of Earth mass in the oort cloud (a cloud surrounding our planetary system) but they would be frozen at these distances," Mr Stern added.

"They would look like a frozen Earth."

Goldilocks zone

Excitement about finding other Earth-like planets is driven by the idea that some might contain life or perhaps, centuries from now, allow human colonies to be set up on them.

The key to this search, said Debra Fischer of San Francisco State University, California, was the Goldilocks zone.

This refers to an area of space in which a planet is just the right distance from its parent star so that its surface is not-too-hot or not-too-cold to support liquid water.

"To my mind there are two things we have to go after; we have to find the right mass planet and it has to be at the right distance from the star," she said.

The AAAS meeting concludes on Monday. "



La vie est un long fleuve tranquille .....

#145    Tommyo

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Posted 18 February 2008 - 01:26 AM

They have been finding planets around stars for several years now by indirect means.  All are of massive size and gas giants.  Ones that dwarf our jupiter.  Its old news.  Rocky planets have yet to be discovered but several upcoming projects from nasa and esa will be able to see the star's planets.  But I am guessing that their arn't hundreds, but rather millions of rocky planets in our galaxy alone.

I came here to chew bubble gum and kick ***...  And I'm all out of bubble gum.

#146    Waspie_Dwarf

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Posted 18 February 2008 - 01:47 AM

Researchers find two new 'unlonely planets'

The University of St Andrews press release is reproduced below:

Friday 15 February 2008

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

Astronomers from the University of St Andrews have discovered a new system of planets with `striking similarities' to our own Solar system.  

Part of an international team, the researchers have found two new planets, similar to Jupiter and Saturn and 5,000 light years away.   Orbiting a star half the mass of the Sun, the planets were discovered using a world-wide net of telescopes - including the UK's Liverpool Telescope on the Canary Islands.  The latest finding brings the search for new planets `closer and closer to home'.

The St Andrews planet hunters, Dr Martin Dominik and Professor Keith Horne, made essential contributions to the discovery of an Earth-like planet in early 2006 using the same technique.

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Dr Martin Dominik

Their recent finding, released on St Valentine's Day, suggests that planets do not favour the single-life but are more likely to be found in family groups.  The two new planets are systematically named OGLE-2006-BLG-109Lb and OGLE-2006-BLG-109Lc.  Dr Dominik, Royal Society University Research Fellow at the St Andrews' School of Physics & Astronomy, said, "Our gravitational microlensing technique is currently best suited for studying extra-solar planets that resemble the gas giants of the Solar System.  This system of planets bears a remarkable similarity to our Solar System, with the ratios of their properties remarkably close to those of Jupiter and Saturn.

"Our finding also suggests that lonesome gas-giant planets are the exception and planetary systems are the rule.  It seems that planets do not like being lonely hearts."

linked-image
Professor Keith Horne

Besides the two new planets, their host star may be surrounded by further planets, similar to others within our own Solar system, although there is no evidence for that.

"The lack of further planetary signals makes it plausible that the more massive of the two planets - OGLE-2006-BLG-109Lb - is the innermost giant planet orbiting its parent star, leaving room for terrestrial planets (like Mercury, Venus, Earth, and Mars) to reside inside its orbit. Moreover planets taking the role of Uranus and Neptune, respectively, could also be present," explained Dr Dominik.

"While most planetary systems around other stars substantially differ from the Solar system, a series of recent detections have brought us closer and closer to home. Sooner rather than later, someone can be expected to discover an Earth-mass planet orbiting a star other than the Sun - and it could be us.  In fact, with our ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search) expert system, even less massive planets could bedetected," he said.

The Liverpool Telescope data that formed part of the discovery of the two new planets were taken as part of the RoboNet microlensing programme, which exploits three robotic telescopes with a diameter of 2 metres, the largest of their kind in the world.

Professor Keith Horne, who leads the programme, points out that microlensing searches can act as vital part of a roadmap towards further space missions. "Apart from individual spectacular discoveries, the technique of gravitational microlensing allows to infer a census of planets within the Milky Way. Once we know that planets similar to Earth are common, it is straightforward to go ahead with finding them and investigating whether these harbour any forms of life," he explained.

ENDS

IMAGES

CREDIT KASI/CBNU/ARCSEC

(KASI: Korea Astronomy and Space Science Institute, CBNU: Chungbuk National University,

ARCSEC: Astrophysical Research Center for the Structure and Evolution of the Cosmos)



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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#147    Waspie_Dwarf

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Posted 18 February 2008 - 02:11 AM

Many, Perhaps Most, Nearby Sun-Like Stars May Form Rocky Planets

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For Release: February 17, 2008

Astronomers have discovered that terrestrial planets might form around many, if not most, of the nearby sun-like stars in our galaxy. These new results suggest that worlds with potential for life might be more common than we thought.

University of Arizona, Tucson, astronomer Michael Meyer and his colleagues used NASA's Spitzer Space Telescope to determine whether planetary systems like ours are common or rare in our Milky Way galaxy. They found that at least 20 percent, and possibly as many as 60 percent, of stars similar to the sun are candidates for forming rocky planets.

Meyer is presenting the findings at the annual meeting of the American Association for the Advancement of Science in Boston. The results appear in the Feb. 1 issue of Astrophysical Journal Letters.

The astronomers used Spitzer to survey six sets of stars, grouped depending on their age, with masses comparable to our sun. The sun is about 4.6 billion years old. "We wanted to study the evolution of the gas and dust around stars similar to the sun and compare the results with what we think the solar system looked like at earlier stages during its evolution," Meyer said.

The Spitzer telescope does not detect planets directly. Instead it detects dust -- the rubble left over from collisions as planets form -- at a range of infrared wavelengths. The hottest dust is detected at the shortest wavelengths, between 3.6 microns and 8 microns. Cool dust is detected at the longest wavelengths, between 70 microns and 160 microns. Warm dust can be traced at 24-micron wavelengths. Because dust closer to the star is hotter than dust farther from the star, the "warm" dust likely traces material orbiting the star at distances comparable to the distance between Earth and Jupiter.

"We found that about 10 to 20 percent of the stars in each of the four youngest age groups shows 24-micron emission due to dust," Meyer said. "But we don't often see warm dust around stars older than 300 million years. The frequency just drops off.

"That's comparable to the time scales thought to span the formation and dynamical evolution of our own solar system," he added. "Theoretical models and meteoritic data suggest that Earth formed over 10 to 50 million years from collisions between smaller bodies."

In a separate study, Thayne Currie and Scott Kenyon of the Smithsonian Astrophysical Observatory, Cambridge, Mass., and their colleagues also found evidence of dust from terrestrial planet formation around stars from 10 to 30 million years old. "These observations suggest that whatever led to the formation of Earth could be occurring around many stars between three million and 300 million years old," Meyer said.

Kenyon and Ben Bromley of the University of Utah, Salt Lake City, have developed planet formation models that provide a plausible scenario. Their models predict warm dust would be detected at 24-micron wavelengths as small rocky bodies collide and merge. "Our work suggests that the warm dust Meyer and colleagues detect is a natural outcome of rocky planet formation. We predict a higher frequency of dust emission for the younger stars, just as Spitzer observes," said Kenyon.

The numbers on how many stars form planets are ambiguous because there's more than one way to interpret the Spitzer data, Meyer said. The warm-dust emission that Spitzer observed around 20 percent of the youngest cohort of stars could persist as the stars age. That is, the warm dust generated by collisions around stars three to 10 million years old could carry over and show up as warm dust emission seen around stars in the 10- to 30- million-year-old range and so on. Interpreting the data this way, about one out of five sun-like stars is potentially planet-forming, Meyer said.

There's another way to interpret the data. "An optimistic scenario would suggest that the biggest, most massive disks would undergo the runaway collision process first and assemble their planets quickly. That's what we could be seeing in the youngest stars. Their disks live hard and die young, shining brightly early on, then fading," Meyer said. "However, smaller, less massive disks will light up later. Planet formation in this case is delayed because there are fewer particles to collide with each other."

If this is correct and the most massive disks form their planets first and the wimpiest disks take 10 to 100 times longer, then up to 62 percent of the surveyed stars have formed, or may be forming, planets. "The correct answer probably lies somewhere between the pessimistic case of less than 20 percent and optimistic case of more than 60 percent," Meyer said.

The next critical test of the assertion that terrestrial planets like Earth could be common around stars like the sun will come next year with the launch of NASA's Kepler mission.

Meyer's 13 co-authors include John Carpenter of the California Institute of Technology in Pasadena. NASA's Jet Propulsion Laboratory in Pasadena manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA.

Rosemary Sullivant 818-354-2274
Jet Propulsion Laboratory, Pasadena, Calif.

Lori Stiles 520-626-4402
University of Arizona, Tucson

jpl2008-027
ssc2008-05


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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#148    Waspie_Dwarf

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Posted 15 March 2008 - 10:05 AM

Spitzer Finds Organics and Water Where New Planets May Grow

For Release: March 13, 2008

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Researchers using NASA's Spitzer Space Telescope have discovered large amounts of simple organic gases and water vapor in a possible planet-forming region around an infant star, along with evidence that these molecules were created there. They've also found water in the same zone around two other young stars.

By pushing the telescope's capabilities to a new level, astronomers now have a better view of the earliest stages of planetary formation, which may help shed light on the origins of our own solar system and the potential for life to develop in others.

John Carr of the Naval Research Laboratory, Washington, and Joan Najita of the National Optical Astronomy Observatory, Tucson, Ariz., developed a new technique using Spitzer's infrared spectrograph to measure and analyze the chemical composition of the gases within protoplanetary disks. These are flattened disks of gas and dust that encircle young stars. Scientists believe they provide the building materials for planets and moons and eventually, over millions of years, evolve into orbiting planetary systems like our own.

"Most of the material within the disks is gas," said Carr, "but until now it has been difficult to study the gas composition in the regions where planets should form. Much more attention has been given to the solid dust particles, which are easier to observe."

In their project, Carr and Najita took an in-depth look at the gases in the planet-forming region in the disk around the star AA Tauri. Less than a million years old, AA Tauri is a typical example of a young star with a protoplanetary disk.

With their new procedures, they were able to detect the minute spectral signatures for three simple organic molecules--hydrogen cyanide, acetylene and carbon dioxide--plus water vapor. In addition, they found more of these substances in the disk than are found in the dense interstellar gas called molecular clouds from which the disk originated. "Molecular clouds provide the raw material from which the protoplanetary disks are created," said Carr. "So this is evidence for an active organic chemistry going on within the disk, forming and enhancing these molecules."

Spitzer's infrared spectrograph detected these same organic gases in a protoplanetary disk once before. But the observation was dependent on the star's disk being oriented in just the right way. Now researchers have a new method for studying the primordial mix of gases in the disks of hundreds of young star systems.

Astronomers will be able to fill an important gap--they know that water and organics are abundant in the interstellar medium but not what happens to them after they are incorporated into a disk. "Are these molecules destroyed, preserved or enhanced in the disk?" said Carr. "Now that we can identify these molecules and inventory them, we will have a better understanding of the origins and evolution of the basic building blocks of life--where they come from and how they evolve." Carr and Najita's research results appear in the March 14 issue of Science.

Taking advantage of Spitzer's spectroscopic capabilities, another group of scientists looked for water molecules in the disks around young stars and found them--twice. "This is one of the very few times that water vapor has been directly shown to exist in the inner part of a protoplanetary disk--the most likely place for terrestrial planets to form," said Colette Salyk, a graduate student in geological and planetary sciences at the California Institute of Technology in Pasadena. She is the lead author on a paper about the results in the March 20 issue of Astrophysical Journal Letters.

Salyk and her colleagues used Spitzer to look at dozens of young stars with protoplanetary disks and found water in many. They honed in on two stars and followed up the initial detection of water with complementary high-resolution measurements from the Keck II Telescope in Hawaii. "While we don't detect nearly as much water as exists in the oceans on Earth, we see essentially only the disk's surface, so the implication is that the water is quite abundant," said Geoffrey Blake, professor of cosmochemistry and planetary sciences at Caltech and one of the paper's co-authors.

"This is a much larger story than just one or two disks," said Blake. "Spitzer can efficiently measure these water signatures in many objects, so this is just the beginning of what we will learn."

"With upcoming Spitzer observations and data in hand," Carr added, "we will develop a good understanding of the distribution and abundance of water and organics in planet-forming disks."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech, also in Pasadena. Caltech manages JPL for NASA.

The National Optical Astronomy Observatory, Tucson, Ariz., is operated by the Association of Universities for Research in Astronomy, under a cooperative agreement with the National Science Foundation. The W.M. Keck Observatory is funded by Caltech, the University of California and NASA, and is managed by the California Association for Research in Astronomy, Kamuela, Hawaii.


Rosemary Sullivant 818-354-2274
Jet Propulsion Laboratory, Pasadena, Calif.

ssc2008-06


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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#149    Waspie_Dwarf

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Posted 15 March 2008 - 10:12 AM

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Credit: NASA/JPL-Caltech/Naval Research Laboratory


Spectrum AA Tauri

This plot of infrared data shows the signatures of water vapor and simple organic molecules in the disk of gas and dust surrounding a young star.

The data on the top line were captured by NASA's Spitzer Space Telescope's spectrograph, which collects light and sorts it according to color, or wavelength. In this case, infrared light from gases around the star AA Tauri was broken up into the wavelengths listed on the horizontal axis of the plot. The sharp spikes are called spectral lines, and each molecule has its own unique pattern, much like a fingerprint. The pattern of spikes reveals the signature of water vapor along with carbon dioxide, hydrogen cyanide, and acetylene--some of the basic building blocks of life.

By comparing the observed data with a model, shown on the lower line, astronomers can determine the physical and chemical details of the region. The model is constructed by adjusting the relative spectral contributions of each chemical component until the theoretical line matches the observed data. The calculations that went into the model provide information on how much of a given material is present, what its temperature is and how much area it covers.

About the Object
Object Name: AA Tauri
Object Type: T Tauri Star
Position (J2000): RA:  4h 34m 55.4s Dec:  +24 28 53
Distance: 140 pc (450 light-years)
Constellation: Taurus


About the Data
Image Credit: NASA/JPL-Caltech/J. Carr (Naval Research Laboratory)
Instrument: IRS
Exposure Date: Oct 15 2005
Exposure Time: 1.4 hours
Release Date: March 13, 2008


Observers
John S. Carr (Naval Research Laboratory)
Joan R. Najita (National Optical Astronomy Observatory)


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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#150    Waspie_Dwarf

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Posted 15 March 2008 - 10:14 AM

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Credit: NASA/JPL-Caltech


Spectrum AS 205N

This plot of infrared data shows the strong signature of water vapor in the disk of gas and dust surrounding a young star.

The data on the top line were captured by NASA's Spitzer Space Telescope's spectrograph, which collects light and sorts it according to color, or wavelength. In this case, infrared light from gases around the star AS 205 N was broken up into the wavelengths listed on the horizontal axis of the plot. The sharp spikes are called spectral lines, and each molecule has its own unique pattern, much like a fingerprint. The pattern of spikes reveals the signature of water vapor, along with smaller amounts of carbon dioxide and hydroxyl.

By comparing the observed data with a model, shown on the lower line, astronomers can determine the physical and chemical details of the region. The model is constructed by adjusting the relative spectral contributions of each chemical component until the theoretical line matches the observed data. The calculations that went into the model provide information on how much of a given material is present, what its temperature is and how much area it covers.

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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