|
Posted by baalke on January 8, 2007, 12:12 pm
Please log in for more thread options
GAS GIANTS JUMP INTO PLANET FORMATION EARLY
(From Lori Stiles, University Communications, 520-626-4402)
Monday, January 08, 2007
-----------------------------------------------
Contact information, Web links, image caption at the end
------------------------------------------------
Gas-giant planets like Jupiter and Saturn form soon after their stars
do,
according to new research.
Observations from NASA's Spitzer Space Telescope show that gas giants
either form within the first 10 million years of a sun-like star's
life, or
not at all. The study offers new evidence that gas-giant planets must
form
early in a star's history. The lifespan of sun-like stars is about 10
billion years.
Ilaria Pascucci of the University of Arizona Steward Observatory in
Tucson
led a team of astronomers who conducted the most comprehensive search
for
gas around 15 different sun-like stars, most with ages ranging from 3
million to 30 million years.
The scientists used Spitzer's heat-seeking infrared eyes to search for
warm
gas in the inner portions of star systems, an area comparable to the
zone
between Earth and Jupiter in our own solar system.
In addition, Pascucci, team member Michael Meyer of the UA Steward
Observatory and their colleagues probed for cold gas in the outer
regions of
these star systems with the Arizona Radio Observatory's 10-meter
Submillimeter Telescope (SMT) on Mount Graham, Ariz. The outer zones of
these star systems are analogous to the region around Saturn's orbit
and
beyond in our own solar system.
All of the stars in the study - including those as young as a few
million
years - have less than 10 percent of Jupiter's mass in gas swirling
around
them, Pascucci said.
"This indicates that gas giant planets like Jupiter and Saturn have
already
formed in these young solar system analogs, or they never will," Meyer
said.
Astronomers suspect that gas around a star may also be important for
sending terrestrial, or rocky, planets like Earth into relatively
circular
orbits as they form. If Earth had a highly elliptical orbit rather than
relatively circular one, its temperature swings would be so extreme
that
humans and other complex organisms might not have evolved.
Many of the sun-like star systems in the study don't currently contain
enough gas to send developing rocky planets into circular orbit,
Pascucci
said. One possibility is that terrestrial planets around these stars
have
highly elliptical orbits that hinder the development of complex life.
Another possibility is that some mechanism other than gas moves the
terrestrial planets into circular orbits once they are fully formed.
"Our
observations tested only the effect of gas," Pascucci said.
Pascucci's paper was published in the Astrophysical Journal in November
2006. The astronomers are presenting a poster of their findings today
at the
209th meeting of the American Astronomical Society in Seattle, Wash.
The
observations were part of the Spitzer Legacy Science Program "Formation
and
Evolution of Planetary Systems" (FEPS). Meyer, a co-author of the
paper, is
the principal investigator of the FEPS program.
The Jet Propulsion Laboratory manages the Spitzer Space Telescope
mission
for NASA's Science Mission Directorate, Washington. Science operations
are
conducted at the Spitzer Science Center at Caltech. JPL is a division
of
Caltech. Spitzer's infrared spectrograph was built by Cornell
University,
Ithaca, N.Y., its development was led by Jim Houck.
The Arizona Radio Observatory offices are centrally located in the
Steward
Observatory building on The University of Arizona campus in Tucson.
This story is also online at JPL Spitzer Web page. For graphics and
more
information about Spitzer, visit
http://www.spitzer.caltech.edu/spitzer. For
more information about the Arizona Radio Observatory, visit
http://aro.as.arizona.edu/. For more information about the FEPS science
team, see http://feps.as.arizona.edu.
-----------------------------------------------------------------
Science Contact Information
Ilaria Pascucci 520-626-5909 pascucci@as.arizona.edu
Michael Meyer 520-626-9199 mmeyer@as.arizona.edu
Related Web sites
http://www.spitzer.caltech.edu/spitzer
http://feps.as.arizona.edu
http://aro.as.arizona.edu/
http://www.spitzer.caltech.edu/Media/releases/ssc2007-02/ssc2007-02a.shtml
----------------------------------------------------------------------
Writer: Linda Vu, Jet Propulsion Laboratory, Pasadena, Calif.
--------------------------------------------------
CAPTION: This is an artist's concept of a hypothetical
10-million-year-old
star system. The bright blur at the center is a star much like our sun.
The
other orb in the image is a gas-giant planet like Jupiter. Wisps of
white
throughout the image represent traces of gas.
Astronomers using NASA's Spitzer Space Telescope have found evidence
showing that gas-giant planets either form within the first 10 million
years
of a sun-like star's life, or not at all. The lifespan for sun-like
stars is
about 10 billion years.
The scientists came to this conclusion after searching for traces of
gas
around 15 different sun-like stars, most with ages ranging from 3
million to
30 million years. With the help of Spitzer's Infrared Spectrometer
instrument, they were able to search for relatively warm gas in the
inner
regions of these star systems, an area comparable to the zone between
Earth
and Jupiter in our own solar system. They also used ground-based radio
telescopes to search for cooler gas in the outer regions of these
systems,
an area comparable to the zone around Saturn and beyond.
Image credit: NASA/JPL-Caltech/T. Pyle (SSC)
------------------------------------------------------------------------
DOWNLOAD ILLUSTRATION AT:
http://www.spitzer.caltech.edu/Media/releases/ssc2007-02/ssc2007-02a.shtml
---------------------------------------------------------------------
|
| Similar Threads | Posted | | Texas Astronomers Discover Mult-Planet System Around Unexpected Star; May Alter Planet-Formation Theories | May 23, 2007, 11:52 am |
| Planet-Forming Disks Might Put the Brakes on Stars (Spitzer) | July 24, 2006, 4:49 pm |
| NASA's Spitzer Finds Water Vapor on Hot, Alien Planet | July 11, 2007, 9:54 pm |
| NASA'S Spitzer Finds Failed Stars May Succeed in Planet Business | October 21, 2005, 9:04 am |
| NASA Finds Extremely Hot Planet, Makes First Exoplanet Weather Map (Spitzer) | May 9, 2007, 8:38 pm |
| Meteor Impacts: Life's Jump Starter? | August 8, 2005, 10:28 am |
| Comets As Toolkits For Jump-Starting Life | December 14, 2006, 4:19 pm |
| NASA's Stardust Findings May Alter View of Comet Formation | March 13, 2006, 4:24 pm |
| Icy Jupiter Moon Throws a Curve Ball at Formation Theories (Amalthea) | May 31, 2005, 2:48 pm |
| New Study Highlights Role of Hit-and-Run Collisions in the Formation of Planets, Asteroids, and Meteorites | January 12, 2006, 2:59 pm |
|
XML Sitemap