NASA's Kepler mission announced today the
discovery of 461 new planet candidates. Four of the potential new
planets are less than twice the size of Earth and orbit in their sun's
"habitable zone," the region in the planetary system where liquid water
might exist on the surface of a planet. "The analysis of increasingly
longer time periods of Kepler data uncovers smaller planets in longer
period orbits-- orbital periods similar to Earth's," said Steve Howell,
Kepler mission project scientist. "It is no longer a question of will we
find a true Earth analogue, but a question of when."
Based on observations conducted from May 2009 to March 2011, the
findings show a steady increase in the number of smaller-size planet
candidates and the number of stars with more than one candidate. The new
data increase the number of stars discovered to have more than one
planet candidate from 365 to 467. Today, 43 percent of Kepler's planet
candidates are observed to have neighbor planets.
"There is no better way to kick off the start of the Kepler extended
mission than to discover more possible outposts on the frontier of
potentially life-bearing worlds," said Christopher Burke, Kepler
scientist at the SETI Institute in Mountain View, Calif., who is leading the analysis.
Since the last Kepler catalog was released in February 2012, the
number of candidates discovered in the Kepler data has increased by 20
percent and now totals 2,740 potential planets orbiting 2,036 stars. The
most dramatic increases are seen in the number of Earth-size and super
Earth-size candidates discovered, which grew by 43 and 21 percent
respectively.
"The large number of multi-candidate systems being found by Kepler
implies that a substantial fraction of exoplanets reside in flat
multi-planet systems," said Jack Lissauer, planetary scientist at NASA's Ames Research Center in Moffett Field, Calif. "This is consistent with what we know about our own planetary neighborhood."
The Kepler space telescope
identifies planet candidates by repeatedly measuring the change in
brightness of more than 150,000 stars in search of planets that pass in
front of, or "transit," their host star. At least three transits are
required to verify a signal as a potential planet. Scientists analyzed
more than 13,000 transit-like signals to eliminate known spacecraft
instrumentation and astrophysical false positives, phenomena that
masquerade as planetary candidates, to identify the potential new
planets. Candidates require additional follow-up observations and
analyses to be confirmed as planets. At the beginning of 2012, 33
candidates in the Kepler data had been confirmed as planets. Today,
there are 105.
The complete list of Kepler planet candidates is available in an interactive table at the NASA Exoplanet
Archive. The archive is funded by NASA's Exoplanet Exploration Program
to collect and make public data to support the search for and
characterization of exoplanets and their host stars.
Source: The Daily Galaxy via NASA/JPL/Kepler Mission
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