The Age of the Carina Young Association and Potential Membership of HD 95086

TL;DR

This study reanalyzes the Carina stellar association's membership and age using Gaia DR2 data, identifying HD 95086 as a potential member and estimating the association's age at approximately 13.3 million years, impacting the classification of some planetary companions.

Contribution

It provides a revised membership list and age estimate for the Carina association, and reclassifies HD 95086's membership based on Gaia data, offering new insights into stellar and planetary characteristics.

Findings

HD 95086 is a potential Carina member with 71% probability.

The age of Carina is estimated at 13.3 million years, younger than previous estimates.

The younger age affects the classification of planetary companions around Carina members.

Abstract

Carina is a nearby young stellar association. So far, only a small number of stars have been clearly identified as members of this association. In this paper we reanalyse the membership of the association in light of Gaia DR2 data, in particular finding that HD 95086 is a potential member (probability of 71%). This star is noteworthy as one of the few stars that hosts both a detected debris disc and a directly imaged planet. It has previously only been considered as a potential member of the Lower Centaurus Crux (LCC) - part of the Scorpius-Centaurus association. We also reanalyse the age of the Carina association. Using a Bayesian inference code applied to infer a solution from stellar evolution models for the most probable (>99%) members of Carina, we infer an age for the association of 13.3$^{+1.1}_{-0.6}$ Myr, much younger than previous studies. Whilst we have revised HD 95086's association membership from LCC to Carina, the fact that we also find Carina to have a younger age, similar to that of LCC, means that the estimates of HD 95086b's mass remain unchanged. However, the younger age of Carina does mean that the companion to another Carina member, HD 44627 (or AB Pic), has a mass that is more clearly in the planet rather than brown dwarf range.