Atmospheric parameters and pulsational properties for a sample of $\delta$\,Sct, $\gamma$\,Dor, and hybrid {\it Kepler} targets

TL;DR

This study spectroscopically characterizes 19 Kepler target stars, analyzing their pulsation modes to classify them as delta Scuti, gamma Doradus, or hybrid pulsators, providing essential data for asteroseismic modeling.

Contribution

It provides detailed spectroscopic parameters and pulsation classifications for a sample of Kepler stars, enhancing the understanding of their pulsational properties and hybrid behavior.

Findings

All stars show both g and p mode pulsations.

Classified stars into pure and hybrid pulsators based on frequency analysis.

Identified one star as a potential binary.

Abstract

We report spectroscopic observations for 19 $\delta$\,Sct candidates observed by the {\it Kepler} satellite both in long and short cadence mode. For all these stars, by using spectral synthesis, we derive the effective temperature, the surface gravity and the projected rotational velocity. An equivalent spectral type classification has been also performed for all stars in the sample. These determinations are fundamental for modelling the frequency spectra that will be extracted from the {\it Kepler} data for asteroseismic inference. For all the 19 stars, we present also periodograms obtained from {\it Kepler} data. We find that all stars show peaks in both low- ($\gamma$\,Dor; g mode) and high-frequency ($\delta$\,Sct; p mode) regions. Using the amplitudes and considering 5\,c/d as a boundary frequency, we classified 3 stars as pure $\gamma$\,Dor, 4 as $\gamma$\,Dor\,-\,$\delta$\ hybrid, Sct, 5 as $\delta$\,Sct\,-\,$\gamma$\,Dor hybrid, and 6 as pure $\delta$\,Sct. The only exception is the star KIC\,05296877 which we suggest could be a binary.