The Metal-Rich Stars Get Richer in Planets For All But Planets With R_P

Ji Wang, Debra A. Fischer (Submitted on 29 Oct 2013)

The metallicity of exoplanet systems serves as a critical diagnostic of planet formation mechanisms. Previous studies have obtained followup observations to measure the metallicity of Kepler planet candidates host stars and show that the planet-metallicity correlation holds for large planets (R_P >= 4 R_E); however, this correlation is not found for smaller planets. Here we define a sample of 1166 multi-planet candidates from Kepler Objects of Interest and use the host star metallicities from Kepler In- put Catalog to study the planet-metallicity correlation. This sample is a factor of 3-5 larger than those used in previous studies. We compare the fraction of sub-solar and super-solar metallicity stars with transiting planets. Although any sample of stars will have incompleteness in the number of detected transiting planets, we expect that these incompleteness factors essentially affect metal-poor and metal-rich stars equally. For orbital period less than 100 days, we confirm a strong planet-metallicity correlation for gas giant planets (5 R_E < R_P <= 22 R_E). The gas giant planet occurrence rate is 2.6 times higher around stars with super-solar metallicity than around stars with the sub-solar metallicity. For Neptune-like planets (2 R_E < RP <= 5 R_E), the planet occurrence rate for the super-solar metallicity sample is 1.4 times higher than the sub- solar metallicity sample. No correlation of planet occurrence rate with metallicity exists for small-radii planets (R_P <= 2 R_E).

Comments: 14 pages, 4 figures, 1 table, submitted to ApJL

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1310.7830 [astro-ph.EP] (or arXiv:1310.7830v1 [astro-ph.EP] for this version)

Submission history From: Ji Wang [v1] Tue, 29 Oct 2013 15:19:23 GMT (503kb)