Asteroseismic analysis of RY Leporis: the post-main sequence HADS in a binary system

TL;DR

This study combines spectroscopic, photometric, and seismic analyses to characterize RY Lep, a binary system with a pulsating primary, revealing its stellar parameters, chemical composition, and evolutionary status.

Contribution

First comprehensive seismic modeling of RY Lep integrating multi-source photometry and spectroscopy, determining its mass, age, and evolutionary phase.

Findings

Dominant pulsation frequency identified as the first radial overtone.

Seismic models suggest RY Lep is a ~2.0 solar mass star in hydrogen shell-burning phase.

Chemical analysis shows underabundance of iron-group elements and enhancement of neutron-capture elements.

Abstract

We present a comprehensive study of the pulsating primary component of the long-period binary system RY Lep. The spectral energy distribution and the absence of detectable lines indicate that the companion is likely a white dwarf. Atmospheric parameters and chemical abundances were determined from a high-resolution spectrum obtained with the the Southern African Large Telescope (SALT). The spectroscopic analysis reveals an underabundance of iron-group elements and an enhancement of neutron-capture elements, including barium and europium, with an overall metallicity of [m/H]$\approx -0.4$. In the next step, we performed the first Fourier analysis of long-term photometric data from ASAS, SuperWASP, and TESS. In the TESS observations, we identify several additional frequencies not present in the ground-based data. The dominant frequency at 4.4415 d$^{-1}$ is identified as a radial mode, most likely the first radial overtone. Finally, seismic modeling of RY Lep was carried out by fitting the dominant mode together with the secondary frequency at 6.5991 d$^{-1}$, considering two possible identification for the latter: the third radial overtone or a dipole mode. Bayesian inference based on Monte Carlo simulations yields a stellar mass of $\sim 2.0 $M$_\odot$ and an age of $\sim 730$ Myr. All viable seismic models place RY Lep in the hydrogen shell-burning evolutionary phase, with a metallicity consistent with the spectroscopic determination.