A long-period substellar object exhibiting a single transit in Kepler

2021/06/30 by Quinn, Samuel N., Rappaport, Saul, Vanderburg, Andrew +11
#Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR)

paper · doi:10.48550/arxiv.2107.00027

Abstract

We report the detection of a single transit-like signal in the Kepler data of the slightly evolved F star KIC4918810. The transit duration is ~45 hours, and while the orbital period (P∼10 years) is not well constrained, it is one of the longest among companions known to transit. We calculate the size of the transiting object to be R_P = 0.910 R_J. Objects of this size vary by orders of magnitude in their densities, encompassing masses between that of Saturn (0.3 M_J) and stars above the hydrogen-burning limit (~80 M_J). Radial-velocity observations reveal that the companion is unlikely to be a star. The mass posterior is bimodal, indicating a mass of either ~0.24 M_J or ~26 M_J. Continued spectroscopic monitoring should either constrain the mass to be planetary or detect the orbital motion, the latter of which would yield a benchmark long-period brown dwarf with a measured mass, radius, and age.

Related

• Evidence for a giant companion orbiting Tabby's star
• A long-period transiting substellar companion in the super-Jupiters to brown dwarfs mass regime and a prototypical warm-Jupiter detected by TESS
• Kepler-1624b Has No Significant Transit Timing Variations
• A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2
• Not So Fast Kepler-1513: A Perturbing Planetary Interloper in the Exomoon Corridor