Sergio Ortolani

Revising the ages of planet-hosting stars

Aims. This article aims to measure the age of stars with planets (SWP) through stellar tracks and isochrones computed with the PAdova and TRieste Stellar Evolutionary Code (PARSEC). Methods. We developed algorithms based on two different techniques for determining the ages of field stars: isochrone placement and Bayesian estimation. Their application to a synthetic sample of coeval stars shows the intrinsic limits of each method. For instance, the Bayesian computation of the modal age tends to select the extreme age values in the isochrones grid. Therefore, we used the isochrone placement technique to measure the ages of 317 SWP. Results. We found that ∼6% of SWP have ages lower than 0.5 Gyr. The age distribution peaks in the interval [1.5, 2) Gyr, then it decreases. However, ∼7% of the stars are older than 11 Gyr. The Sun turns out to be a common star that hosts planets, when considering its evolutionary stage. Our SWP age distribution is less peaked and slightly shifted towards lower ages if compared with ages in the literature and based on the isochrone fit. In particular, there are no ages below 0.5 Gyr in the literature.

Age consistency between exoplanet hosts and field stars

Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photometric surveys do not tend to target slow rotators, inactive or metal-rich stars. Nevertheless, we suspect that observational biases could also impact transiting-planet hosts. This paper aims to evaluate 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 PARSEC models. The notable aspects of our algorithm include the treatment of element diffusion, activity checks in terms of

The RATS project.

log{R_{HK}}

Search for an optimal Eddington Planet Finding Field

and

Disk-shocking and the mass function of globular clusters

vsin{i}

The GOTHAM survey: chemical evolution of Milky Way globular clusters

, 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

A revision on ages of stars-hosting planets

rho_{star}

The ages of stars with planets

allows us to compute stellar luminosity even if the distance is not available, by combining

Parameters for SMC clusters from CMD modeling

rho_{star}

UBV(RI)cHalpha photometry in omega Cen (Bellini+, 2009)

with the spectroscopic