Friday, January 29, 2016

BD+20594b: a Neptune Sized MegaEarth

A Neptune-sized Exoplanet Consistent with a Pure Rock Composition


Espinoza et al


We report the discovery of BD+20594b, a Neptune-sized exoplanet consistent with a pure rock composition, made using photometry from Campaign 4 of the two-wheeled Kepler (K2) mission. The host star is a bright (V=11.04, Ks=9.37), slightly metal poor ([Fe/H]=−0.15±0.05 dex) solar analogue located at 152.1+9.7−7.4 pc from Earth, for which we find a radius of R∗=0.928+0.055−0.040R⊙ and a mass of M∗=0.961+0.032−0.029M⊙. A joint analysis of the K2 photometry and HARPS radial velocities reveal that the planet is in a ≈42 day orbit around its host star, has a radius of 2.23+0.14−0.11R⊕, and a mass of 16.3+6.0−6.1M⊕. The data at hand are most consistent with a pure rock composition with a low volatile content, potentially making it a rare exception among Neptune-sized exoplanets discovered so far.

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