Follow-up observations of pulsating subdwarf B stars: Multisite campaigns on PG 1618+563B and PG 0048+091

Abstract

We present follow-up observations of pulsating subdwarf B (sdB) stars as part of our efforts to resolve the pulsation spectra for use in asteroseismological analyses. This paper reports on multisite campaigns of the pulsating sdB stars PG 1618+563B and PG 0048+091. Data were obtained from observatories placed around the globe for coverage from all longitudes. For PG 1618+563B, our five-site campaign uncovered a dichotomy of pulsation states: Early during the campaign the amplitudes and phases (and perhaps frequencies) were quite variable while data obtained late in the campaign were able to fully resolve five stable pulsation frequencies. For PG 0048+091, our five-site campaign uncovered a plethora of frequencies with short pulsation lifetimes. We find them to have observed properties consistent with stochastically excited oscillations, an unexpected result for subdwarf B stars. We discuss our findings and their impact on subdwarf B asteroseismology.

arXiv comment50 pages including 17 figures and 10 tables. Accepted for publication in the Astrophysical Journal

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• A pulsation analysis of K2 observations of the subdwarf B star PG1142-037 during Campaign 1: A subsynchronously rotating ellipsoidal variable
• Discovery of new TESS pulsating hot subdwarfs
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• Whole Earth Telescope Observations of the subdwarf B star KPD 1930+2752: A rich, short period pulsator in a close binary
• Time-series Spectroscopy and Photometry of the Pulsating Subdwarf B Star PG 1219+534 (KY UMa)
• The EXOTIME project: Signals in the $O-C$ diagrams of the rapidly pulsating subdwarfs DW Lyn, V1636 Ori, QQ Vir, and V541 Hya
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