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### Occurrence of Earth-like planets around GKM Stars

posted Nov 5, 2013, 8:12 AM by Abel Mendez   [ updated Nov 5, 2013, 8:47 AM ]
Here we combine and interpret results from Kopparapu (2013) and Petigura et al. (2013) on the occurrence of Earth-like planets around red-dwarf (type M) and Sun-like (type G and K) stars, respectively. Both studies used NASA Kepler results. Based on their occurrence estimates we calculated the mean separation and 95% confidence distance for the solar neighborhood (<10pc). These numbers suggest that there is over a 95% probability of finding an Earth-like planet around a Sun-like star in the solar neighborhood. The probability is higher for those around M-dwarf stars.

Table 1. Occurrence (ηE), separation (δ), and 95% confidence distance (d95%) of Earth-like planets (0.5 — 2.0 RE in the HZ) around M-dwarfs and GK stars. The study of Petigura et al. (2013) only considered 1.0 — 2.0 RE planets. Calculations assume that there are 198 stellar systems with M-dwarf stars and 50 with GK-stars in the solar neighborhood (<10pc).

 M-dwarfs (Kopparapu, 2013) GK stars (Petigura et al., 2013) Habitable Zone Definition a (AU)* ηE δE (ly) dE 95% (ly) ηE δE (ly) dE 95% (ly) Conservative (1) 0.99 — 1.69 0.51 +0.10/-0.20 6.25 10.1 0.086 ± 0.03 17.9 28.9 Empirical (1) 0.75 — 1.84 0.61 +0.07/-0.15 5.89 9.51 0.14 ± 0.05 15.2 24.6 Simple Flux (2) 0.5 — 2 — — — 0.22 ± 0.08 13.1 21.1 Desert-H2 Planets (3) 0.38 — 10 — — — 0.52 ± 0.19 9.8 15.9

HZ References: (1)

Table Notes:
a = semi-major axis (values shown for G stars, check here for other types of stars).
ηE (eta Earth) = fraction of Earth-like planets per star.
δ(delta Earth) = mean distance between stellar systems with Earth-like planets.
d95% = 95% confidence distance for an Earth-like planet.