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Announcing 461 New Kepler Planet Candidates
01.07.2013
bar graph of Kepler planet candidate numbers

Kepler was front and center at the beginning of the 221st American Astronmomical Society Meeting today in Long Beach CA. You may listen to recordings of the first AAS press conference, "Exoplanets Coming & Going Everywhere," which is in 4 parts:

The first two panelists at the press conference spoke about Kepler:

  • Planet Candidates Observed by Kepler: Two Years of Precision Photometry - Christopher Burke (SETI Institute)
  • At Least One in Six Stars Has an Earth-size Planet - Francois Fressin (Harvard-Smithsonian Center for Astrophysics)

For more about Fressin's presentation, see Harvard Smithsonian Center for Astrophysics Press Release 2013-01. Excerpt: ...50 percent of stars have a planet of Earth-size or larger in a close orbit. By adding larger planets, which have been detected in wider orbits up to the orbital distance of the Earth, this number reaches 70 percent.

slide from Fressin's presentation

...it looks like practically all Sun-like stars have planets. ...17 percent of stars have a planet 0.8 - 1.25 times the size of Earth in an orbit of 85 days or less. About one-fourth of stars have a super-Earth (1.25 - 2 times the size of Earth) in an orbit of 150 days or less. ...The same fraction of stars has a mini-Neptune (2 - 4 times Earth) in orbits up to 250 days long. Larger planets are much less common. Only about 3 percent of stars have a large Neptune (4 - 6 times Earth), and only 5 percent of stars have a gas giant (6 - 22 times Earth) in an orbit of 400 days or less.

Download Fressin's presentation slides (PPTX, 8.3 MB)

For more about Burke's presentation, see NASA RELEASE: 13-008 (excerpt below) and download

Excerpt: NASA's Kepler mission Monday announced 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.

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.

"There is no better way to kickoff 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.

locations of Kepler planet candidates in Kepler full field image

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 new data increases 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.

"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."

...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.

scatter plot radius vx period of Kepler planet candidate numbers

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 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 at Ames. "It is no longer a question of will we find a true Earth analogue, but a question of when."

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.

Overall, the Kepler team’s efforts and the results of the data were prominently featured throughout the AAS Meeting. In total, 33 talks and 26 posters using Kepler data were presented, and distributed over 23 different scientific sessions. This is a testament to the diversity within the Kepler community. Five special Kepler sessions were spread over three days of the meeting. These special sessions were:

  1. Zeroing in on eta-Earth with NASA's Kepler Mission
  2. Planets and Planetary Systems Identified by Kepler
  3. Astrophysics with Kepler's High Precision Photometry I
  4. Astrophysics with Kepler's High Precision Photometry II, and
  5. Kepler Exoplanets.

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