Status Report

Age consistency between exoplanet hosts and field stars

By SpaceRef Editor
November 8, 2015
Filed under , , ,

Andrea Bonfanti, Sergio Ortolani, Valerio Nascimbeni
(Submitted on 5 Nov 2015)

Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photometric surveys do not tend to target slow rotators, inactive and metal-rich stars. Nevertheless, we suspect that observational biases could impact also transiting-planet hosts. This paper aims at evaluating how selection effects reflect on the evolutionary stage of both a limited sample of transiting-planet host stars (TPH) and a wider sample of planet-hosting stars detected through radial velocity analysis. Then, thanks to uniform derivation of stellar ages, a homogeneous comparison between exoplanet hosts and field star age distributions is developed. Stellar parameters have been computed through our custom-developed isochrone placement algorithm, according to Padova evolutionary models. The notable aspects of our algorithm include the treatment of element diffusion, activity checks in terms of logR′HK and vsini and the evaluation of the stellar evolutionary speed in the Hertzsprung-Russel Diagram in order to better constrain age. Working with TPH, the observational stellar mean density ρ? allows to compute stellar luminosity even if the distance is not available, by combining ρ? with the spectroscopic logg. The median value of the TPH ages is ∼5 Gyr. Even if this sample is not so large, however the result is very similar to what we found for the sample of spectroscopic hosts, whose modal and median values are [3, 3.5) Gyr and ∼4.8 Gyr, respectively. Thus these stellar samples suffer almost the same selection effects. We also conclude that the age of our Sun is consistent with the age distribution of solar neighbourhood MS stars with spectral types from late-F to early-K, regardless of harbouring planets or not. We considered the possibility that our selected samples are older than the average disc population.

Comments: 13 pages, 1 longtable, 9 figures. Accepted by A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:1511.01744 [astro-ph.SR] (or arXiv:1511.01744v1 [astro-ph.SR] for this version)
Submission history
From: Andrea Bonfanti
[v1] Thu, 5 Nov 2015 13:56:54 GMT (1372kb,D)

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