[FPSPACE] FW: NASA Telescope Finds Planets Thrive Around Stellar Twins

[LARRY KLAES]

>From: "NASA Jet Propulsion Laboratory" <info at jpl.nasa.gov>
>Reply-To: <info at jpl.nasa.gov>
>Subject: NASA Telescope Finds Planets Thrive Around Stellar Twins Date: 
>Thu, 29 Mar 2007 10:34:03 -0700
>
>MEDIA RELATIONS OFFICE
>JET PROPULSION LABORATORY
>CALIFORNIA INSTITUTE OF TECHNOLOGY
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>http://www.jpl.nasa.gov
>
>Whitney Clavin (818) 354-4673
>Jet Propulsion Laboratory, Pasadena, Calif.
>
>News Release:  2007-036 					  March 29, 2007
>
>NASA Telescope Finds Planets Thrive Around Stellar Twins
>
>The double sunset that Luke Skywalker gazed upon in the film "Star Wars" 
>might not be
>a fantasy.
>
>Astronomers using NASA's Spitzer Space Telescope have observed that 
>planetary
>systems - dusty disks of asteroids, comets and possibly planets - are at 
>least as abundant
>in twin-star systems as they are in those, like our own, with only one 
>star.  Since more
>than half of all stars are twins, or binaries, the finding suggests the 
>universe is packed
>with planets that have two suns. Sunsets on some of those worlds would 
>resemble the
>ones on Luke Skywalker's planet, Tatooine, where two fiery balls dip below 
>the horizon
>one by one.
>
>"There appears to be no bias against having planetary system formation in 
>binary
>systems," said David Trilling of the University of Arizona, Tucson, lead 
>author of a new
>paper about the research appearing in the April 1 issue of the 
>Astrophysical Journal.
>"There could be countless planets out there with two or more suns."
>
>Previously, astronomers knew that planets could form in exceptionally wide 
>binary
>systems, in which stars are 1,000 times farther apart than the distance 
>between Earth and
>the sun, or 1,000 astronomical units. Of the approximately 200 planets 
>discovered so far
>outside our solar system, about 50 orbit one member of a wide stellar duo.
>
>The new Spitzer study focuses on binary stars that are a bit more snug, 
>with separation
>distances between zero and 500 astronomical units. Until now, not much was 
>known
>about whether the close proximity of stars like these might affect the 
>growth of planets.
>Standard planet-hunting techniques generally don't work well with these 
>stars, but, in
>2005, a NASA-funded astronomer found evidence for a planet candidate in one 
>such
>multiple-star system 
>(http://www.jpl.nasa.gov/news/news.cfm?release=2005-115).
>
>Trilling and his colleagues used Spitzer's infrared, heat-seeking eyes to 
>look not for
>planets, but for dusty disks in double-star systems. These so-called debris 
>disks are made
>up of asteroid-like bits of leftover rock that never made it into rocky 
>planets. Their
>presence indicates that the process of building planets has occurred around 
>a star, or stars,
>possibly resulting in intact, mature planets.
>
>In the most comprehensive survey of its kind, the team looked for disks in 
>69 binary
>systems between about 50 and 200 light-years away from Earth. All of the 
>stars are
>somewhat younger and more massive than our middle-aged sun. The data show 
>that
>about 40 percent of the systems had disks, which is a bit higher than the 
>frequency for a
>comparable sample of single stars. This means that planetary systems are at 
>least as
>common around binary stars as they are around single stars.
>
>In addition, the astronomers were shocked to find that disks were even more 
>frequent
>(about 60 percent) around the tightest binaries in the study. These coziest 
>of stellar
>companions are between zero and three astronomical units apart. Spitzer 
>detected disks
>orbiting both members of the star pairs, rather than just one. Extra-tight 
>star systems like
>these are where planets, if they are present, would experience 
>Tatooine-like sunsets.
>
>"We were very surprised to find that the tight group had more disks," said 
>Trilling. "This
>could mean that planet formation favors tight binaries over single stars, 
>but it could also
>mean tight binaries are just dustier. Future observations should provide a 
>better answer."
>
>The Spitzer data also reveal that not all binary systems are friendly 
>places for planets to
>form. The telescope detected far fewer disks altogether in intermediately 
>spaced binary
>systems, between three to 50 astronomical units apart. This implies that 
>stars may have to
>be either very close to each other, or fairly far apart, for planets to 
>arise.
>
>"For a planet in a binary system, location is everything," said co-author 
>Karl Stapelfeldt
>of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
>
>"Binary systems were largely ignored before," added Trilling. "They are 
>more difficult to
>study, but they might be the most common sites for planet formation in our 
>galaxy."
>
>Other authors on the paper include: John Stansberry, George Rieke and Kate 
>Su of the
>University of Arizona; Richard Gray of the Appalachian State University, 
>Boone, N.C.;
>Chris Corbally of the Vatican Observatory, Tucson; Geoff Bryden, Andy Boden 
>and
>Charles Beichman of JPL; and Christine Chen of the National Optical 
>Astronomical
>Observatory, Tucson.
>
>JPL manages Spitzer for NASA's Science Mission Directorate, Washington. 
>Science
>operations are conducted at the Spitzer Science Center at the California 
>Institute of
>Technology, also in Pasadena. The multiband imaging photometer for Spitzer 
>was built
>by Ball Aerospace Corporation, Boulder, Colo.; the University of Arizona; 
>and Boeing
>North American, Canoga Park, Calif. Co-author Rieke is the principal 
>investigator.
>
>For more information and graphics, visit www.spitzer.caltech.edu/Media and
>http://www.nasa.gov/spitzer .  More information about extrasolar planets 
>and NASA's
>planet-finding program is at http://planetquest.jpl.nasa.gov .
>
>-end-
>
>