Monday, August 8, 2016

EPIC 211391664b is a Warm Neptune-Sized Planet

Barragán et al. (2016) present the detection of EPIC 211391664b, a transiting Neptune-sized planet in a 10.14 day orbit around an F-type star that is located ~1400 light years away. From transit and radial velocity observations, EPIC 211391664b has ~4.3 times the radius and 32.2 ± 8.1 times the mass of Earth. For comparison, Neptune has 3.9 times the radius and 17.1 times the mass of Earth. Although only slightly larger in size than Neptune, EPIC 211391664b has almost twice the mass of Neptune. EPIC 211391664b joins a relatively small group of Neptune-sized planets whose mass and radius are known to better than 3σ. The equilibrium temperature on EPIC 211391664b is estimated to be ~1100 K. In about 3 billion years from now, EPIC 211391664b is expected to be engulfed as its host star evolves into a red giant.

Barragán et al. (2016), “EPIC 211391664b: A 32-Mᴇ Neptune-sized planet in a 10-day orbit transiting an F8 star”, arXiv:1608.01165 [astro-ph.EP]