The EXOTIME project: Signals in the O-C diagrams of the rapidly pulsating subdwarfs DW Lyn, V1636 Ori, QQ Vir, and V541 Hya

F. MacKebrandt, S. Schuh, R. Silvotti, S. L. Kim, D. Kilkenny, E. M. Green, R. Lutz, T. Nagel, J. L. Provencal, T. Otani, T. D. Oswalt, S. Benatti, L. Lanteri, A. Bonanno, A. Frasca, R. Janulis, M. Paparó, L. Molnár, R. Claudi, R. H. Østensen

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Aims. We aim to investigate variations in the arrival time of coherent stellar pulsations due to the light-travel time effect to test for the presence of sub-stellar companions. Those companions are the key to one possible formation scenario of apparently single sub-dwarf B stars. Methods. We made use of an extensive set of ground-based observations of the four large amplitude p-mode pulsators DW Lyn, V1636 Ori, QQ Vir, and V541 Hya. Observations of the TESS space telescope are available on two of the targets. The timing method compares the phase of sinusoidal fits to the full multi-epoch light curves with phases from the fit of a number of subsets of the original time series. Results. Observations of the TESS mission do not sample the pulsations well enough to be useful due to the (currently) fixed two-minute cadence. From the ground-based observations, we infer evolutionary parameters from the arrival times. The residual signals show many statistically significant periodic signals, but no clear evidence for changes in arrival time induced by sub-stellar companions. The signals can be explained partly by mode beating effects. We derive upper limits on companion masses set by the observational campaign.

Original languageEnglish (US)
Article numberA108
JournalAstronomy and astrophysics
Volume638
DOIs
StatePublished - Jun 1 2020

Keywords

  • Asteroseismology
  • Planets and satellites: detection
  • Stars: horizontal-branch
  • Subdwarfs
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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