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Uncovering the planets and stellar activity of CoRoT-7 using only radial velocities

J. P. S. Faria, R. D. Haywood, B. J. Brewer, P. Figueira, M. Oshagh, A. Santerne, N. C. Santos

Abstract
Stellar activity can induce signals in the radial velocities of stars, complicating the detection of orbiting low-mass planets. We present a method to determine the number of planetary signals present in radial-velocity datasets of active stars, using only radial-velocity observations. Instead of considering separate fits with different number of planets, we use a birth-death Markov chain Monte Carlo algorithm to infer the posterior distribution for the number of planets in a single run. In a natural way, the marginal distributions for the orbital parameters of all planets are also inferred. This method is applied to HARPS data of CoRoT-7. We confidently recover the orbits of both CoRoT-7b and CoRoT-7c although the data show evidence for the presence of additional signals.

Keywords
methods: data analysis – planetary systems – stars: individual: CoRoT-7 – techniques: radial velocities

Notes
All data and software presented in this article are available online at https://github.com/j-faria/exoBD-CoRoT7

Astronomy and Astrophysics
Volume 588, Article Number A31, Number of pages 7
2016 April

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia