Defining the instability strip of pulsating post-AGB binary stars from ASAS and NSVS photometry

L. L. Kiss, A. Derekas, Gy M. Szabó, T. R. Bedding, L. Szabados

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

We analyse public domain time-series photometric observations of 30 known and candidate binary post-AGB stars for measuring pulsation and orbital periods. We derive periodicities for 17 stars for the first time in the literature. Besides identifying five new RV Tauri type pulsating variables (three with the RVb phenomenon, i.e. long-term changes of the mean brightness), we find multiply periodic (or possibly irregular) post-AGB stars on the two edges of the instability strip. The temperature dependence of the peak-to-peak light-curve amplitudes clearly indicates the changes in excitation as post-AGB stars evolve through the strip. One object, the peculiar Type II Cepheid ST Pup, showed a period increase from 18.5 to 19.2 d, which is consistent with the known period fluctuations in the past. In HD 44179, the central star of the Red Rectangle nebula, we see very similar asymmetric light curve than was measured 10-15 yr ago, suggesting a very stable circumstellar environment. In contrast to this, HD 213985 shows coherent but highly non-repetitive brightness modulation, indicating changes in the circumstellar cloud on a similar time-scale to the orbital period.

Original languageEnglish
Pages (from-to)1338-1348
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume375
Issue number4
DOIs
Publication statusPublished - Mar 2007

Keywords

  • Stars: evolution
  • Stars: late-type
  • Stars: oscillations
  • Supergiants

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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