TERRESTRIAL, HABITABLE-ZONE EXOPLANET FREQUENCY FROM KEPLER
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
Data from Kepler's first 136 days of operation are analyzed to determine the distribution of exoplanets with respect to radius, period, and host-star spectral type. The analysis is extrapolated to estimate the percentage of terrestrial, habitable-zone (HZ) exoplanets. The Kepler census is assumed to be complete for bright stars (magnitude <14.0) having transiting planets >0.5 Earth radius and periods <42 days. It is also assumed that the size distribution of planets is independent of orbital period and that there are no hidden biases in the data. Six significant statistical results are found: there is a paucity of small planet detections around faint target stars, probably an instrumental effect; the frequency of mid-size planet detections is independent of whether the host star is bright or faint; there are significantly fewer planets detected with periods <3 days, compared to longer periods, almost certainly an astrophysical effect; the frequency of all planets in the population with periods <42 days is 29%, broken down as terrestrials 9%, ice giants 18%, and gas giants 3%; the population has a planet frequency with respect to period which follows a power-law relation dN/dP {approx} P{sup {beta}-1}, with {beta} {approx_equal} 0.71 {+-} 0.08; and an extrapolation to longer periods gives the frequency of terrestrial planets in the HZs of FGK stars as {eta}{sub Circled-Plus} {approx_equal} (34 {+-} 14)%. Thus about one-third of FGK stars are predicted to have at least one terrestrial, HZ planet.
- OSTI ID:
- 22011983
- Journal Information:
- Astrophysical Journal, Vol. 745, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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