ASYMMETRIC TRANSIT CURVES AS INDICATION OF ORBITAL OBLIQUITY: CLUES FROM THE LATE-TYPE DWARF COMPANION IN KOI-13

作者：Szabo Gy M^*; Szabo R; Benko J M; Lehmann H; Mezo Gy; Simon A E; Kovari Zs; Hodosan G; Regaly Zs; Kiss L L

来源：Astrophysical Journal Letters, 2011, 736(1): L4.

DOI：10.1088/2041-8205/736/1/L4

• binaries: visual
• brown dwarfs
• stars: individual (CCDM J19079+4652AB, KOI-13)

KOI-13.01, a planet-sized companion in an optical double star, was announced as one of the 1235 Kepler planet candidates in 2011 February. The transit curves show significant distortion that was stable over the similar to 130 days time span of the data. Here we investigate the phenomenon via detailed analyses of the two components of the double star and a re-reduction of the Kepler data with pixel-level photometry. Our results indicate that KOI-13 is a common proper motion binary, with two rapidly rotating components (v sin i approximate to 65-70 km s(-1)). We identify the host star of KOI-13.01 and conclude that the transit curve asymmetry is consistent with a companion orbiting a rapidly rotating, possibly elongated star on an oblique orbit. The radius of the transiter is 2.2 R-J, implying an irradiated late-type dwarf, probably a hot brown dwarf rather than a planet. KOI-13 is the first example for detecting orbital obliquity for a substellar companion without measuring the Rossiter-McLaughlin effect with spectroscopy.

• 出版日期2011-7-20