The GW Vir Instability Strip in Light of New Observations of PG 1159 Stars: Discovery of Pulsations in the Central Star of A72 and Variability of RX J0122.9-7521

0582170 - ASÚ 2024 RIV US eng J - Journal Article
Sowicka, P. - Handler, G. - Jones, D. - Caldwell, J. A. R. - van Wyk, F. - Paunzen, E. - Bąkowska, K. - Peralta de Arriba, L. - Suárez-Andrés, L. - Werner, K. - Karjalainen, Marie - Holdsworth, L.D.
The GW Vir Instability Strip in Light of New Observations of PG 1159 Stars: Discovery of Pulsations in the Central Star of A72 and Variability of RX J0122.9-7521.
Astrophysical Journal Supplement Series. Roč. 269, č. 1 (2023), č. článku 32. ISSN 0067-0049. E-ISSN 1538-4365
EU Projects: European Commission(XE) ESA-PRODEX PEA4000127913
Institutional support: RVO:67985815
Keywords : pulsating variable stars * stellar pulsations * non-radial pulsations
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 8.7, year: 2022
Method of publishing: Open access

We present the results of new time-series photometric observations of 29 pre-white dwarf stars of PG 1159 spectral type, carried out in the years 2014-2022. For the majority of stars, a median noise level in Fourier amplitude spectra of 0.5-1.0 mmag was achieved. This allowed the detection of pulsations in the central star of planetary nebula A72 (Abell 72), consistent with g modes excited in GW Vir stars, and variability in RX J0122.9-7521 that could be due to pulsations, binarity, or rotation. For the remaining stars from the sample that were not observed to vary, we placed upper limits for variability. After combination with literature data, our results place the fraction of pulsating PG 1159 stars within the GW Vir instability strip at 36%. An updated list of all known PG 1159 stars is provided, containing astrometric measurements from the recent Gaia DR3 data, as well as information on physical parameters, variability, and nitrogen content. Those data are used to calculate luminosities for all PG 1159 stars to place the whole sample on the theoretical Hertzsprung-Russell diagram for the first time in that way. The pulsating stars are discussed as a group, and arguments are given that the traditional separation of GW Vir pulsators in “DOV” and “PNNV” stars is misleading and should not be used.
Permanent Link: https://hdl.handle.net/11104/0350248