Kepler-445, Kepler-446 and the Occurrence of Compact Multiples Orbiting mid-M Dwarf Stars
2015 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 801, no 1, 18Article in journal (Refereed) Published
We confirm and characterize the exoplanetary systems Kepler-445 and Kepler-446: two mid-M dwarf stars, each with multiple, small, short-period transiting planets. Kepler-445 is a metal-rich ([ Fe/H] = + 0.25 0.10) M4 dwarf with three transiting planets, and Kepler-446 is a metal-poor ([ Fe/H] = -0.30 0.10) M4 dwarf also with three transiting planets. Kepler-445c is similar toGJ 1214b: both in planetary radius and the properties of the host star. The Kepler-446 system is similar to the Kepler-42 system: both are metal-poor with large galactic space velocities and three short-period, likely rocky transiting planets that were initially assigned erroneously large planet-to-star radius ratios. We independently determined stellar parameters from spectroscopy and searched for and fitted the transit light curves for the planets, imposing a strict prior on stellar density in order to remove correlations between the fitted impact parameter and planet-to-star radius ratio for short-duration transits. Combining Kepler-445, Kepler-446, and Kepler-42, and isolating all mid-M dwarf stars observed by Kepler with the precision necessary to detect similar systems, we calculate that 21+ 7 -5 % of mid-M dwarf stars host compact multiples ( multiple planets with periods of less than 10 days) for a wide range of metallicities. We suggest that the inferred planet masses for these systems support highly efficient accretion of protoplanetary disk metals by mid-M dwarf protoplanets.
Place, publisher, year, edition, pages
2015. Vol. 801, no 1, 18
planetary systems, stars: fundamental parameters, stars: individual (KOI-2704, KOI-2842, Kepler-42, Barnard's Star), stars: late-type, stars: low-mass
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-248813DOI: 10.1088/0004-637X/801/1/18ISI: 000350488700018OAI: oai:DiVA.org:uu-248813DiVA: diva2:801461