Spectral Properties of Cool Stars: Extended Abundance Analysis of 1617 Planet Search Stars

TL;DR

This study provides a comprehensive catalog of stellar properties and elemental abundances for 1626 stars, using automated spectral analysis, and offers new relations for stellar parameters and insights into model atmosphere effects.

Contribution

It introduces a uniform spectral synthesis method for determining stellar parameters and abundances across a large star sample, with improved precision and new empirical relations.

Findings

Achieved high precision in stellar parameters (25 K in Teff, 0.01 dex in [M/H])

Derived new relations between effective temperature and macroturbulence

Identified potential issues with model atmospheres affecting abundance trends

Abstract

We present a catalog of uniformly determined stellar properties and abundances for 1626 F, G, and K stars using an automated spectral synthesis modeling procedure. All stars were observed using the HIRES spectrograph at Keck Observatory. Our procedure used a single line list to fit model spectra to observations of all stars to determine effective temperature, surface gravity, metallicity, projected rotational velocity, and the abundances of 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, & Y). Sixty percent of the sample had Hipparcos parallaxes and V-band photometry which we combined with the spectroscopic results to obtain mass, radius, and luminosity. Additionally, we used the luminosity, effective temperature, metallicity and alpha-element enhancement to interpolate in the Yonsei-Yale isochrones to derive mass, radius, gravity, and age ranges for those stars. Finally, we determined new relations between effective temperature and macroturbulence for dwarfs and subgiants. Our analysis achieved precisions of 25 K in Teff , 0.01 dex in [M/H], 0.028 dex for log g and 0.5 km/s in v sin ibased on multiple observations of the same stars. The abundance results were similarly precise, between 0.01 and - 0.04 dex, though trends with respect to Teff remained for which we derived empirical corrections. The trends, though small, were much larger than our uncertainties and are shared with published abundances. We show that changing our model atmosphere grid accounts for most of the trend in [M/H] between 5000 K and 5500 K indicating a possible problem with the atmosphere models or opacities.