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Kepler-10c and a New Method to Validate Planets
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Francois Fressin

Presentation Slides (Power Point, 7.29 MB) from the Press Conference of 2011 May 23 at the American Astronomical Society conference in Boston.

[See the press event slides, with presenter's audio]

Today the Kepler team, as a result of a study led by Francois Fressin from the Harvard-Smithsonian Center for Astrophysics, is announcing another member of the Kepler-10 family, called Kepler-10c (larger foreground object in the image on this page). It has a radius of 2.2 times that of Earth's, and it orbits the star every 45 days. Both Kepler-10b and 10c would be blistering hot worlds.

Kepler-10 Stellar Family Portrait
Kepler-10 Stellar Family Portrait. This artist's conception depicts the Kepler-10 star system. Image credit: NASA/Ames/JPL-Caltech

The Kepler-10 system is located about 560 light-years away near the Cygnus and Lyra constellations. Kepler has discovered two planets around this star. Kepler-10b is, to date, the smallest known rocky exoplanet, or planet outside our solar system (dark spot against yellow sun). This planet, which has a radius of 1.4 times that of Earth's, whips around its star every .8 days. Its discovery was announced in Jan. 2011. [See Kepler-10b News Item: NASA's Kepler Mission Discovers Its First Rocky Planet.]

Kepler-10c was first identified by Kepler, and later validated using a combination of a computer simulation technique called "Blender," and NASA's Spitzer Space Telescope. Both of these methods are powerful ways to validate the Kepler planets that are too small and faraway for ground-based telescopes to confirm using the radial-velocity technique. The Kepler team says that a large fraction of their discoveries will be validated with both of these methods.

Blender: a new way to validate Kepler planet discoveries.
Blender: a new way to validate Kepler planet discoveries. Credit: NASA/Wendy Stenzel.

In the case of Kepler-10c, scientists can be 99.998 percent sure that the signal they detected is from an orbiting planet. Part of this confidence comes from the fact that Spitzer, an infrared observatory, saw a signal similar to what Kepler detected in visible light. If the signal were coming from something other than an orbiting planet -- for example an indistinguishable background pair of orbiting stars -- then scientists would expect to see different signals in visible and infrared light.

These findings are described in Fressin, et. al, ‘Kepler-10c, a 2.2-Earth radius transiting planet in a multiple system’.

Light curve of an eclipsing binary star that could mimic a transiting planet.
Light curve of an eclipsing binary star that could mimic a transiting planet.

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