Pulsations of the High-Amplitude $\delta$ Scuti Star YZ Bootis

TL;DR

This study analyzes the pulsations of the high-amplitude δ Scuti star YZ Boo using photometric data, identifying fundamental modes, harmonics, and period changes, and constrains its physical parameters and evolutionary stage.

Contribution

The paper presents the first detection of the fourth and fifth harmonics in YZ Boo and provides updated period, mass, and age estimates based on combined observational and theoretical analysis.

Findings

Detected the fourth and fifth harmonics of pulsation.

Derived a new period of 0.104091579 days.

Estimated mass as 1.61 solar masses and age as 1.44 billion years.

Abstract

We present a study on the pulsations of the high-amplitude $\delta$ Scuti star YZ Boo based on photometric observations in Johnson $V$ and $R$ bands with both the Nanshan 1-m telescope of Xinjiang Astronomical Observatory (XAO) and the Xinglong 85-cm telescope of National Astronomical Observatories, Chinese Academy of Sciences (NAOC). The Fourier analysis of the light curves reveals the fundamental radial mode and its five harmonics, with the fourth and the fifth newly detected. 39 new times of light maximum are determined from the light curves, and combined with those in the literature, we construct the $O - C$ diagram and derive a new ephemeris and the determination of a new value of the updated period 0.104091579(2). Besides, the $O - C$ diagram reveals an increasing period change rate of YZ Boo. Theoretical models are calculated and constrained with the observationally determined parameters of YZ Boo. The mass and age of YZ Boo are hence derived as $M$ = 1.61 $\pm$ 0.05 $M_\odot$ and $age$ = (1.44 $\pm$ 0.14) $\times$ 10$^9$ yr, respectively. With both the frequency of the fundamental radial mode and the period change rate, YZ Boo is located at the post-main-sequence stage.