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Ideas on gas-giant planet formation take shape
March 23, 2006Rocky planets such as Earth and Mars are born when small particles smash together to form larger, planet-sized clusters in a planet-forming disk, but researchers are less sure about how gas-giant planets such as Jupiter and Saturn form. Is core accretion-the process that creates their smaller, terrestrial cousins-responsible? Or could an alternate model known as disk instability-in which the planet-forming disk itself actually fragments into a number of planet-sized clumps-be at work? Could both be possible under different circumstances?
Recent work from the Carnegie Institution's Department of Terrestrial Magnetism explores both possibilities. This and other relevant work regarding planet formation is presented at the NASA Astrobiology Science Conference (AbSciCon) 2006 at the Ronald Reagan Building in Washington, D.C. March 26-30. See http://abscicon2006.arc.nasa.gov/ for details.
The telltale gravitational dimples resemble craters on the Moon with sunlight shining in from the side: the inside of the edge nearest the star is shadowed, while the star-facing edge is illuminated. The bright side heats up and the shadowed side remains cool, yielding a distinct thermal pattern that an Earth-based observer should be able to see in the infrared spectrum. "If we could detect this signature in a protoplanetary disk, it would indicate the presence of a young planetary body that could go on to form a gas-giant via core accretion," Jang-Condell said.
In some situations, however, core accretion seems an unlikely model for gas-giant planet formation. For example, theoretical computer models by DTM staff member Alan Boss2 suggest that disk instability best explains planet formation around M dwarf stars, which have masses from one tenth to one half that of the Sun. Core accretion would likely take more than 10 million years around these small, gravitationally weak stars, while disk instability happens quickly enough to yield gas-giant planets in as little as 1,000 years.
"M dwarf stars dominate the stellar population in the solar neighborhood, and so are attractive targets for searching for habitable planets," Boss said. "The models show that gas-giant planets are indeed likely to format distances sufficiently large enough to permit the later formation of habitable, terrestrial planets."
Other talks and posters on planet formation at the conference include: A study of organic matter in the planet-forming disks of three young stars, ranging in age from less than one million to over 300 million years3; methods to detect water ice, methane ice, and silicate dust in the planet-forming disks of distant stars4; and a method to deduce the composition of far-off planets based on their mass and radius5.
Carnegie Institution
Planet Formation Current Events and Planet Formation News RSS32 new exoplanets found
The latest batch of exoplanets announced today comprises no less than 32 new discoveries. Including these new results, data from HARPS have led to the discovery of more than 75 exoplanets in 30 different planetary systems.
Dirty stars make good solar system hosts
Some stars are lonely behemoths, with no surrounding planets or asteroids, while others sport a skirt of attendant planetary bodies. New research published this week in The Astrophysical Journal Letters explains why the composition of the stars often indicates whether their light shines into deep space, or whether a small fraction shines onto orbiting planets.
Twin Keck Telescopes Probe Dual Dust Disks
Astronomers using the twin 10-meter telescopes at the W. M. Keck Observatory in Hawaii have explored one of the most compact dust disks ever resolved around another star.
James Webb Space Telescope Begins to Take Shape at Goddard
NASA's James Webb Space Telescope is starting to come together. A major component of the telescope, the Integrated Science Instrument Module structure, recently arrived at NASA Goddard Space Flight Center in Greenbelt, Md. for testing in the Spacecraft Systems Development and Integration Facility.
Trigger-happy star formation
A new study from two of NASA's Great Observatories provides fresh insight into how some stars are born, along with a beautiful new image of a stellar nursery in our Galaxy.
Primitive asteroids in the main asteroid belt may have formed far from the sun
Many of the objects found today in the asteroid belt located between the orbits of Mars and Jupiter may have formed in the outermost reaches of the solar system.
University of Hawaii at Manoa astronomers discover pair of solar systems in the making
Two University of Hawai'i at Mānoa astronomers have found a binary star-disk system in which each star is surrounded by the kind of dust disk that is frequently the precursor of a planetary system.
Radio telescope images reveal planet-forming disk orbiting twin suns
Astronomers are announcing today that a sequence of images collected with the Smithsonian's Submillimeter Array (SMA) clearly reveals the presence of a rotating molecular disk orbiting the young binary star system V4046 Sagittarii.
AAAS, leading Texas scientists urge state board to reject anti-evolution effort
Leading members of the Texas scientific community, in collaboration with the American Association for the Advancement of Science (AAAS), have urged the Texas State Board of Education to reject amendments to the state's draft science standards that would undermine sound science teaching.
Jupiter-like Planets Could Form Around Twin Suns
Life on a planet ruled by two suns might be a little complicated. Two sunrises, two sunsets. Twice the radiation field.
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Astrophysics of Planet Formation by Philip Armitage (Author) The study of planet formation has been revolutionized by recent observational breakthroughs, which have allowed the detection and characterization of extrasolar planets, the imaging of protoplanetary disks, and the discovery of the Solar System's Kuiper Belt. Written for beginning graduate students, this textbook provides a basic understanding of the astrophysical processes that shape the formation of planetary systems. It begins by describing the structure and evolution of protoplanetary disks, moves on to the formation of planetesimals, terrestrial and gas giant planets, and concludes by surveying new theoretical ideas for the early evolution of planetary systems. Covering all phases of planet formation - from protoplanetary disks to the dynamical evolution of planetary systems - this... |
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Shiprock Land Formation, Shiprock, USA Lonely Planet Collection Photographic Poster Print by Jim Wark, 36x48 by Art.com Art.com is the world's largest retailer of art prints, posters, photographs, and framed artwork. With our huge selection of over 400,000 prints, you'll easily find the perfect piece for your home, office, or classroom. Our art is printed on quality paper. When you order framed artwork, the piece is built by our team of in-house professionals. Visit our Amazon store today at www.amazon.com/artdotcom to find Special Offers and search for products based on 'Artist Name' and 'Subject Categories' such as Movie, Music, Vintage, TV, Children, Travel, Kitchen, Museum Art, Animals, Floral, Motivational, and Sports. Art.com is dedicated to providing you with high quality products and service by offering you 100% satisfaction guaranteed. We ship internationally to over 80 countries. Decorate your... |
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Shiprock Land Formation, Shiprock, USA Lonely Planet Collection Framed Art Poster Print by Jim Wark, 39x49 by Art.com Art.com is the world's largest retailer of art prints, posters, photographs, and framed artwork. With our huge selection of over 400,000 prints, you'll easily find the perfect piece for your home, office, or classroom. Our art is printed on quality paper. When you order framed artwork, the piece is built by our team of in-house professionals. Visit our Amazon store today at www.amazon.com/artdotcom to find Special Offers and search for products based on 'Artist Name' and 'Subject Categories' such as Movie, Music, Vintage, TV, Children, Travel, Kitchen, Museum Art, Animals, Floral, Motivational, and Sports. Art.com is dedicated to providing you with high quality products and service by offering you 100% satisfaction guaranteed. We ship internationally to over 80 countries. Decorate your... |
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