Spectroscopic and photometric study of the new δ Scuti star ASAS J063309+1810.8

Abstract

We present BVR observations and low-resolution spectra collected by the Kottamia Astronomical Observatory 1.88 m telescope (KAO) for the new pulsating star ASAS J063309+1810.8 (hereafter it will be called ASAS06+18). The photometric analysis revealed that the star is a δ Scuti star with low amplitude (a=0.054-0.099 in V mag.) and a short period (102.604 min). Fourier analysis of the light curves reveals the fundamental mode with two harmonics. The photometric analysis yielded a new value of the updated frequency of 13.0035232 cd–1 with an amplitude of 49.93 mmag at phases 0.326 and S/N 21.75 and two frequencies (20.2099237cd–1, 5.9130945cd–1). Given the available data, 37 new times of maximum light are presented, and an updated ephemeris for the star and its O-C data. Assuming its period decreases and changes smoothly, a new value of (1/P)dP/dtis determined. We calculated the effective temperature and surface gravity as Teff=7125±250 K and logg=4.0±0.2 dex from model atmosphere analysis of the star's spectra at different phases. The bolometric magnitude Mbol=2.798±0.016, radius R=1.577±0.077Rʘ, luminosity L=5.714±1.066Lʘ, the mass is M=1.595 Mʘ, and pulsation constant Q=0m.0338±0.0003. The star's locations in the evolutionary mass-luminosity and mass-radius relationships are discussed.