Determination of oscillation frequencies and stellar properties of three Delta Scuti variable stars using Kepler data

Abstract

Asteroseismology is the science that deals with the oscillations in the stars with the goal of understanding the stellar structure. In this study, photometric data of Kepler mission have been used for the asteroseismic study of Delta Scuti type pulsating stars. The light curve analysis of three short cadences Kepler datasets of Delta Scuti stars has been presented. The pulsation frequencies were determined by applying a discrete Fourier transformation with the pre-whitening process. The full light curve of Kepler target KIC 9700322 revealed dominant radial fundamental frequency at 9.792 ± 0.002 d-1 and 1st overtone frequency at 12.569 ± 0.002 d-1 accompanied by a large number of frequency multiples. Non-radial frequencies of mode l = 2 quintuplet were detected with the frequency spacing of 0.134 d-1 and it provided a rotation period of the star as 6.19 days, which was detected as the peak of 0.159 d-1 in frequency spectra. Using the fundamental period, a value for relative density of the star was estimated as 0.10 ± 0.04 relative to the sun. Furthermore, the full dataset of KIC 11754974 was subjected to frequency analysis and the radial fundamental pulsation frequency and its 1st overtone were detected at 16.3451 ± 0.0002 d-1 and 21.3997 ± 0.0002 d-1, respectively. l = 2 frequency quintuplet was detected with a frequency spacing of 0.22 d-1 and determined the rotation period and relative density of the star as 3.83 days and 0.29 ± 0.01, respectively. KIC 9845907 was identifi ed as a purely radial pulsator. The fundamental pulsation frequency was recovered as 17.597 ± 0.002 d-1 with two other dominant modes of overtones at 22.850 ± 0.002 d-1 and 28.210 ± 0.002 d-1. The relative density of the star was determined as 0.34 ± 0.06.