This artist's concept illustrates Kepler-16b, the first planet known to definitively orbit two stars - what's called a circumbinary planet. The planet, which can be seen in the foreground, was discovered by NASA's Kepler mission.
Credit: NASA/JPL-Caltech/T. Pyle
Sibling suns -- made famous in the "Star
Wars" scene where Luke Skywalker gazes toward a double sunset -- and the
planets around them may be more common than we've thought, and Cornell
University astronomers are presenting new ideas on how to find them.
Astronomers could discover a plethora of planets around binary star
systems ¬- stars that rotate around each other -- by measuring with high
precision how stars move around each other, looking for disturbances
exerted by possible exoplanets. So explains new research, "Survival of
Planets Around Shrinking Stellar Binaries," published in the Proceedings of the National Academy Sciences, July 9, by Diego J. Munoz, Cornell postdoctoral researcher, and Dong Lai, professor of astronomy.
What once was fictional as young Skywalker saw the double suns from
Tatooine is astronomical reality four decades later. Normal binary suns
orbit each other every eight to 100 days, and the Kepler telescope
easily can detect those exoplanets as they transit each sun.
Trouble starts in compact binary sun systems -- where sibling suns
move closer together -- making it difficult for the most advanced
telescopes to find them. Essentially, for Kepler and other telescopes,
the planetary orbital plane of these double suns and their accompanying
planets might be out of whack -- or misaligned -- rendering them
invisible to us. "The current observational strategy inevitably misses a
population of Tatooine planets, but future observations may reveal
their existence," said Munoz.
NASA's Kepler telescope monitors star brightness in a Milky Way
region near the constellation Cygnus, the swan. Measuring photons,
Kepler detects lower light values -- and thus, a planetary transit.
Munoz explains that suns in the close binary system likely were once
standard systems that have lost energy and shrunk, bringing the suns
closer together. As the sibling sun's distance decreases, the orbits of
that system's planets become misaligned, rendering it impossible for the
Kepler telescope to detect planets -- which no longer cross in the
front of the suns.
Munoz and Lai suggest scouting for exoplanet-caused disturbances for
compact binary star systems, to determine a new population of
circumbinary planets. Said Munoz: "Since this type of 'compact' binary
is very common, it had been very puzzling that no planets had been
detected."
This research was funded by the National Science Foundation and by NASA.
Story Source:
The above post is reprinted from
materials provided by
Cornell University. The original item was written by Blaine Friedlander.
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