Atmospheric Parameters of 169 F, G, K and M-type Stars in the Kepler Field

TL;DR

This study derives precise atmospheric parameters for 169 Kepler stars using spectroscopic analysis, identifying new binary systems and comparing methods to improve stellar characterization for asteroseismic and planetary research.

Contribution

It provides the first spectroscopic atmospheric parameters for 67 stars and compares two analysis methods, highlighting systematic differences for stars hotter than 6000 K.

Findings

First spectroscopic parameters for 67 stars.

Identification of two double-lined spectroscopic binaries.

Systematic differences between analysis methods for stars above 6000 K.

Abstract

The asteroseismic and planetary studies, like all research related to stars, need precise and accurate stellar atmospheric parameters as input. We aim at deriving the effective temperature (Teff), the surface gravity (log g), the metallicity ([Fe/H]), the projected rotational velocity (v sin i) and the MK type for 169 F, G, K, and M-type Kepler targets which were observed spectroscopically from the ground with five different instruments. We use two different spectroscopic methods to analyse 189 high-resolution, high-signal-to-noise spectra acquired for the 169 stars. For 67 stars, the spectroscopic atmospheric parameters are derived for the first time. KIC 9693187 and 11179629 are discovered to be double-lined spectroscopic binary systems. The results obtained for those stars for which independent determinations of the atmospheric parameters are available in the literature are used for a comparative analysis. As a result, we show that for solar-type stars the accuracy of present determinations of atmospheric parameters is +/- 150 K in Teff, +/- 0.15 dex in [Fe/H], and +/-? 0.3 dex in log g. Finally, we confirm that the curve-of-growth analysis and the method of spectral synthesis yield systematically different atmospheric parameters when they are applied to stars hotter than 6,000 K.