Asteroseismology of the pulsating extremely low-mass white dwarf SDSS J111215.82+111745.0: a model with $p$-mode pulsations consistent with the observations

Abstract

SDSS J111215.82+111745.0 is the second pulsating extremely low-mass white dwarf discovered. Two short-period pulsations, 107.56 and 134.275 s, were detected on this star, which would be the first observed pressure mode ($p$-mode) pulsations observed on a white dwarf. While the two potential $p$-modes have yet to be confirmed, they make SDSS J111215.82+111745.0 an interesting object. In this work, we analyzed the whole set of seven periods observed on SDSS J111215.82+111745.0. We adopt three independent period-spacing tests to reveal a roughly 93.4 s mean period spacing of $\ell =1$ $g$-modes, which gives added credence to the $\ell =1$ identifications. Then we perform asteroseismic modeling for this star, in which the H chemical profile is taken as a variable. The stellar parameters $M=0.1650\pm 0.0137$ $M_{\odot }$ and $T_{\mathrm{eff}}=9750\pm 560$ K are determined from the best-fit model and the H/He chemical profiles are also defined. The two suspected $p$-modes are also well represented in the best-fit model, and both the stellar parameters and the pulsation frequencies are in good agreement with the values derived from spectroscopy.

25 pages, 6 figures, 3 tables, accepted for publication in ApJ

References in corpus (13)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
• Pulsating White Dwarf Stars and Precision Asteroseismology
• Seismological studies of ZZ Ceti stars. I. The model grid and the application to individual stars
• PSR J1738+0333: The First Millisecond Pulsar + Pulsating White Dwarf Binary
• Fine Grid Asteroseismology of R548 and G117-B15A
• Pruning The ELM Survey: Characterizing Candidate Low-Mass White Dwarfs Through Photometric Variability
• Pulsating low-mass white dwarfs in the frame of new evolutionary sequences: I. Adiabatic properties
• Toward High Precision Seismic Studies of White Dwarf Stars: Parametrization of the Core and Tests of Accuracy
• Pulsating low-mass white dwarfs in the frame of new evolutionary sequences: V. Asteroseismology of ELMV white dwarf stars
• Discovery, TESS Characterization, and Modeling of Pulsations in the Extremely Low Mass White Dwarf GD 278

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