Sunday, August 7, 2016

A Year on KELT-16b is Less than 24 Hours

Oberst et al. (2016) present the discovery of KELT-16b, a highly irradiated, ultra-short period hot-Jupiter transiting a relatively bright F-type main sequence star. Transit and radial velocity observations indicate that KELT-16b has ~1.415 times the radius and ~2.75 times the mass of Jupiter, giving it a mean density of roughly 1.2 times the density of water. KELT-16b circles its host star every 23 hours 15 minutes. This planet joins WASP-18b, WASP-19b, WASP-43b, WASP-103b and HATS-18b as the only transiting hot-Jupiters with orbital periods under a day. The host star of KELT-16b has ~ 1.211 times the mass and ~ 1.360 times the radius of the Sun, and its effective temperature is 6236 ± 54 K.

Due to its ultra-short orbit, KELT-16b is highly irradiated by its host star, and its estimated equilibrium temperature is ~2453 K. The large day-to-night temperature difference on KELT-16b may be extreme enough for gaseous titanium oxide (TiO) and vanadium oxide (VO) to condense and rain out at the planet’s day-night terminator. At present, KELT-16b orbits only ~1.7 Roche radii from its host star. The Roche radius is basically the distance from its host star whereby KELT-16b is expected to become tidally disrupted. Tidal evolution models predict that KELT-16b could be tidally shredded by its host star in as little as half a million years.

Oberst et al. (2016), “KELT-16b: A highly irradiated, ultra-short period hot Jupiter nearing tidal disruption”, arXiv:1608.00618 [astro-ph.EP]