Abstract
ABSTRACT We report the analysis of high temporal resolution ground- and space-based photometric observations of SZ Lyncis, a binary star one of whose components is a high amplitude δ Scuti. UBVR photometric observations were obtained from Mt. Abu Infrared Observatory and Fairborn Observatory; archival observations from the WASP project were also included. Furthermore, the continuous, high-quality light curve from the TESS project was extensively used for the analysis. The well resolved light curve from TESS reveals the presence of 23 frequencies with four independent modes, 13 harmonics of the main pulsation frequency of 8.296943 ± 0.000002 d−1, and their combinations. The frequency 8.296 d−1 is identified as the fundamental radial mode by amplitude ratio method and using the estimated pulsation constant. The frequencies 14.535, 32.620, and 4.584 d−1 are newly discovered for SZ Lyn. Out of these three, 14.535 and 32.620 d−1 are identified as non-radial lower order p modes and 4.584 d−1 could be an indication of a g mode in a δ Scuti star. As a result of frequency determination and mode identification, the physical parameters of SZ Lyn were revised by optimizations of stellar pulsation models with the observed frequencies. The theoretical models correspond to 7500 K ≤ Teff ≤ 7800 K and log(g) = 3.81 ± 0.06. The mass of SZ Lyn was estimated to be close to 1.7–2.0 M⊙ using evolutionary sequences. The period–density relation estimates a mean density (ρ) of 0.1054 ± 0.0016 g cm−3.
Highlights
The study of multi-periodic stellar pulsations represents a unique methodology for studying the interior of a star (Aerts et al 2010; Aerts 2019)
We present a detailed analysis of SZ Lyncis, HD 67390 (RA=08h 09m 35.8s, DEC=+44◦ 28 17.6 ) a High Amplitude δ Scuti (HADS) type binary star, mv= 9.1 mag, with reported pulsation and orbital period 0.12053793 days and 1173.5 days, respectively (Soliman et al 1986)
The f1 of 8.296 d−1, that we identify as the fundamental radial mode, had previously been identified by Gazeas et al (2004) and is further confirmed by the asteroseismic technique of amplitude ratio method in the Sec. 4
Summary
The study of multi-periodic stellar pulsations represents a unique methodology for studying the interior of a star (Aerts et al 2010; Aerts 2019). Δ Scuti stars which simultaneously pulsate in p-modes and gravity g-modes excited by the κ mechanism and the convective flux blocking mechanism, respectively, are commonly referred to as hybrid stars (Bowman & Kurtz 2018) These stars are of intermediate mass ranging between 1.5 to 2.5 M (Aerts et al 2010), most of them are in the core hydrogen burning or shell hydrogen burning phase and possess convective cores. We present a detailed analysis of SZ Lyncis, HD 67390 (RA=08h 09m 35.8s, DEC=+44◦ 28 17.6 ) a High Amplitude δ Scuti (HADS) type binary star, mv= 9.1 mag, with reported pulsation and orbital period 0.12053793 days and 1173.5 days, respectively (Soliman et al 1986). We have discussed the results with a detailed consideration of the limitations and uncertainties of our analysis in Sec. 6 and summarized the results under Sec. 7
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