Age-velocity relations with GALEX $FUV$-determined ages of Sun-like, solar neighborhood stars

Abstract

AbstractA relationship between chromospheric activity and age is calibrated for FGK dwarf stars using GALEX$FUV$ F U V magnitudes and Gaia$(G_{BP} - G)$ ( G B P − G ) colors. Such a calibration between GALEX$FUV$ F U V magnitudes and stellar age has utility in population studies of dwarfs for further understanding of the chemical evolution of the Milky Way. As an illustration of one such application we have investigated a population of Sun-like, solar neighborhood stars for their metallicities and velocity dispersions; a cross-matched sample of FGK type dwarf stars from Casagrande et al. (2011) with the Gaia and GALEX catalogs. Using calibrated relationships between $FUV$ F U V magnitudes and age, we determined a chromospheric activity indicator, $Q$ Q , and stellar age, $\tau $ τ , for each dwarf. We constructed age-velocity (AVR) and age-metallicity (AMR) relations with empirically-determined $FUV$ F U V ages. Power law fits to AVR plots are consistent with heating mechanism models within the literature. We further demonstrate that perigalactic distance and eccentricity versus $FUV$ F U V -age plots are consistent with an “inside out” formation history model.