Exoplanets & Exomoons

MCMCI: A Code To Fully Characterize An Exoplanetary System

By Keith Cowing
Press Release
January 9, 2020
Filed under
MCMCI: A Code To Fully Characterize An Exoplanetary System
Extrasolar planets

By analysing the transit LC of a planet-hosting star or the induced RV oscillations, many useful information on the planet may be retrieved. However, inferring the physical parameters of the planet (mass, size, semi-major axis, etc.) requires the preliminary knowledge of some parameters of the host star, especially its mass and/or radius, that are generally inferred through theoretical evolutionary models.

The paper aims at presenting and testing a whole algorithm devoted to the complete characterization of an exoplanetary system thanks to the global analysis of photometric and/or RV time-series combined to observational stellar parameters derived either from spectroscopy or photometry. We developed an integrated tool called MCMCI that combines the Markov Chain Monte Carlo approach for analysing photometric and/or RV time-series with a proper interpolation within stellar evolutionary isochrones and tracks (known as Isochrone placement) to be performed at each chain step, to retrieve stellar theoretical parameters, such as age, mass and radius. We tested the MCMCI both on the HD 219134 multiplanetary system hosting two transiting rocky super-Earths and on WASP-4, that hosts a bloated hot Jupiter.

Even considering different input approaches, a final convergence was reached within the code, we found good agreement with the results already stated in the literature and we obtained more precise output parameters, especially concerning planetary masses. The MCMCI tool offers the opportunity of performing an integrated analysis of an exoplanetary system, without splitting it into the preliminary stellar characterization through theoretical models, but rather favouring a close interaction between the light-curve analysis and the isochrones, so that the parameters recovered at each step of the MCMC enter as input of the Isochrone placement.

Andrea Bonfanti, Michaël Gillon
(Submitted on 29 Dec 2019)
Comments: 18 pages, 6 figures, 6 tables. Accepted for publication in A&A. Source code will be uploaded on GitHub soon
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:1912.12632 [astro-ph.EP] (or arXiv:1912.12632v1 [astro-ph.EP] for this version)
Submission history
From: Andrea Bonfanti
[v1] Sun, 29 Dec 2019 11:16:15 UTC (1,256 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻