Characterizing the pulsations of the ZZ Ceti star KUV 02464+3239

TL;DR

This study analyzes the pulsation modes of the ZZ Ceti star KUV 02464+3239, identifying multiple frequencies, modeling its internal structure, and exploring amplitude variations and mode trapping effects.

Contribution

First detailed period search and modeling of KUV 02464+3239, revealing its pulsation modes, amplitude variations, and constraining its stellar parameters with new asteroseismic models.

Findings

Resolved multiperiodic pulsations with 6 frequencies.

Identified 3 best-fit stellar models with specific masses and compositions.

Observed short-term amplitude variations and assessed mode trapping.

Abstract

We present the results on period search and modeling of the cool DAV star KUV 02464+3239. Our observations resolved the multiperiodic pulsational behaviour of the star. In agreement with its position near the red edge of the DAV instability strip, it shows large amplitude, long period pulsation modes, and has a strongly non-sinusoidal light curve. We determined 6 frequencies as normal modes and revealed remarkable short-term amplitude variations. A rigorous test was performed for the possible source of amplitude variation: beating of modes, effect of noise, unresolved frequencies or rotational triplets. Among the best-fit models resulting from a grid search, we selected 3 that gave l=1 solutions for the largest amplitude modes. These models had masses of 0.645, 0.650 and 0.680 M_Sun. The 3 `favoured' models have M_H between 2.5x10^-5 - 6.3x10^-6 M_* and give 14.2 - 14.8 mas seismological parallax. The 0.645 M_Sun (11400 K) model also matches the spectroscopic log g and T_eff within 1 sigma. We investigated the possibility of mode trapping and concluded that while it can explain high amplitude modes, it is not required.