CoRoT-22 b: a validated 4.9 RE exoplanet in 10-day orbit

TL;DR

This paper validates CoRoT-22 b as a transiting exoplanet with a radius of about 4.9 Earth radii and a 10-day orbit, using Bayesian analysis and multiple observational constraints, despite the lack of direct radial velocity confirmation.

Contribution

It introduces a comprehensive Bayesian validation method for exoplanets where ground-based follow-up is limited, demonstrating its effectiveness with CoRoT-22 b.

Findings

The planet has a radius of approximately 4.9 Earth radii.

The orbital period is about 9.76 days.

The planet's mass is constrained to be less than 49 Earth masses.

Abstract

The CoRoT satellite has provided high-precision photometric light curves for more than 163,000 stars and found several hundreds of transiting systems compatible with a planetary scenario. If ground-based velocimetric observations are the best way to identify the actual planets among many possible configurations of eclipsing binary systems, recent transit surveys have shown that it is not always within reach of the radial-velocity detection limits. In this paper, we present a transiting exoplanet candidate discovered by CoRoT whose nature cannot be established from ground-based observations, and where extensive analyses are used to validate the planet scenario. They are based on observing constraints from radial-velocity spectroscopy, adaptive optics imaging and the CoRoT transit shape, as well as from priors on stellar populations, planet and multiple stellar systems frequency. We use the fully Bayesian approach developed in the PASTIS analysis software, and conclude that the planet scenario is at least 1400 times more probable than any other false positive scenario. The primary star is a metallic solar-like dwarf, with Ms = 1.099+-0.049 Msun and Rs = 1.136 (+0.038,-0.090) Rsun . The validated planet has a radius of Rp = 4.88 (+0.17,-0.39) RE and mass less than 49 ME. Its mean density is smaller than 2.56 g/cm^3 and orbital period is 9.7566+-0.0012 days. This object, called CoRoT-22 b, adds to a large number of validated Kepler planets. These planets do not have a proper measurement of the mass but allow statistical characterization of the exoplanet population.