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

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 $P_{rot}=35.0\pm 6.7$ 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.

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