Stellar atmospheres of nearby young solar analogs

Abstract

High-resolution ( R≈90,000) spectra of 34 nearby, young Sun-like stars were analyzed using stellar atmosphere models to estimate effective photosphere temperatures, surface gravities, and the abundance of certain heavy elements (C, Na, Mg, Si, S, Ca, Ti, Fe, and Ni). The effective temperatures derived from spectroscopy were compared with temperatures estimated using optical and near-infrared photometry. In many cases the spectroscopic temperatures are significantly higher than the photometric estimates, possibly as a result of spottedness or chromospheric activity on these active stars. Values of effective temperature, surface gravity, and luminosity were compared to theoretical stellar evolution tracks and the evolutionary status of these objects was evaluated. The correlation between heavy element abundance patterns and kinematics (space motion) was also examined. Two nearby stars that were tentatively assigned to the Hyades cluster based on kinematics have Fe abundances that are also consistent with membership in that cluster. Members of the Ursa Major kinematic group exhibit a range of [Fe/H] values but have monotonic [Si/Fe]. These two observations suggest that heterogeneous incorporation of the heavy elements into protostars is creating the variation in metallicity. Local Association members have a distinctly different Si/Fe that probably reflects their distinct origin and chemical inheritance.