The Volans-Carina association: An X-ray Bridge Between Younger and Older Stellar Populations

At a distance of ~100pc and an age of 80-120Myr, the Volans-Carina association (VCA) occupies an under-sampled region of the distance-age parameter space of nearby stellar populations, making it an important benchmark for studying the evolution of stellar coronal activity in X-rays. The VCA is relatively compact on the sky and hosts a modest population of 65 candidate members, of which 19 have confirmed membership based on full 3D kinematics. Its limited spatial extent and manageable membership size enable a near-complete X-ray census that is not feasible for richer associations such as the Pleiades or Hyades, allowing us to probe the X-ray luminosity function across a wide stellar mass range.
In this work, we present an X-ray census of the VCA. We revisit the membership list originally compiled by Gagné et al. (2018), using Gaia DR3 astrometry and photometry, together with new radial velocity values derived from a specialized automated search. This revision raises doubts on the membership of three candidates and three confirmed members, underscoring the importance of reassessing young association memberships using updated kinematic information. We use data from ROSAT, eROSITA, and XMM-Newton, achieving X-ray coverage for approximately 94% of the secure members and candidates. This high level of completeness allows us to reconstruct an X-ray sequence for the association, extending down to ~0.2Msolar. As a function of Gaia colors, we present the resulting distributions of X-ray luminosity and fractional X-ray luminosity. Our results provide one of the most complete views to date of coronal activity in an intermediate-age association, allowing us to produce a direct comparison with younger and older populations without being dominated by upper limits.