Asteroseismology of sz lyn using multi-band high time resolution photometry from ground and space

TL;DR

This study combines ground and space-based high-resolution photometry to analyze the pulsation modes of SZ Lyn, a binary star with a δ Scuti component, revealing multiple frequencies and refining stellar parameters through mode identification.

Contribution

It is the first detailed multi-band, high time resolution analysis of SZ Lyn using TESS and archival data, identifying new pulsation frequencies and modes, and updating stellar parameters.

Findings

Detected 23 frequencies including 4 independent modes.

Identified fundamental radial mode and new non-radial p-modes.

Estimated stellar parameters: T_eff 7500-7800 K, mass 1.7-2.0 M_sun.

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 $\delta$ 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$\pm$0.000002 d$^{-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 d$^{-1}$, 32.620 d$^{-1}$ and 4.584 d$^{-1}$ are newly discovered for SZ Lyn. Out of these three, 14.535 d$^{-1}$ 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 $\delta$ 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 $\le $T$_{\rm eff}$ $\le$ 7800 K, log(g)=3.81$\pm$0.06. The mass of SZ Lyn was estimated to be close to 1.7--2.0 M$_\odot$ using evolutionary sequences. The period-density relation estimates a mean density $\rho$ of 0.1054$\pm$0.0016 g cm$^{-3}$