A triplet of the only pulsation mode detected in the DAV star G132-12

TL;DR

This study presents detailed observations of the DAV star G132-12, revealing a triplet of pulsation modes that provide insights into its rotation and structure, making it a valuable target for studying white dwarf cooling.

Contribution

The paper identifies a triplet of pulsation modes in G132-12, confirming its $l=1$ g-mode and deriving its rotational period and inclination, which was not previously known.

Findings

Detected three pulsation frequencies forming a triplet

Derived the star's rotational period as approximately 35 hours

Estimated the inclination of the star's rotational axis at 70 degrees

Abstract

Hydrogen atmosphere pulsating white dwarfs, also known as DAV stars, are the most abundant type of pulsating white dwarfs. High-temperature DAV stars exhibit in general a small number of pulsation modes and stable frequencies. G132-12 is one of the pulsating hydrogen atmosphere white dwarf stars which lies close to the blue edge of the instability strip. Previous researches reported that G132-12 might have only one pulsation mode with the period of 212.69 s. To study the pulsation properties of G132-12 in detail, we carried out a bi-site observation campaign in October 2019. Time series photometric data were collected during around 154 hours in total. A Fourier Analysis reveals 3 frequencies which are identified as the triplet of a $l = 1$ g-mode pulsation with the period of 212.499 s. The rotational period is derived as $P_{rot} = 35.0\pm6.7$ hours and the inclination of the rotational axis to the line of sight is $70^{\circ}$. G132-12 could be an ideal target for measuring the cooling scale of this white dwarf star with only one excited pulsation mode detected.