New observations and asteroseismic analysis of the subdwarf B pulsator PG 1219+534

Valérie Van Grootel, Marie Julie Péters, Elizabeth M. Green, Stéphane Charpinet, Pierre Brassard, Gilles Fontaine

Research output: Contribution to journalArticlepeer-review

Abstract

We present a new asteroseismic modeling of the hot B subdwarf (sdB) pulsator PG 1219+534, based on a 3-month campaign with the Mont4K/Kuiper combination at Mt Bigelow (Arizona) and on updated atmospheric parameters from high S/N low and medium resolution spectroscopy. On the basis of the nine independent pulsation periods extracted from the photometric light curve, we carried out an astroseismic analysis by applying the forward modeling approach using our latest (third and fourth generation) sdB models. Atmospheric parameters (Teff = 34 258 ± 170 K, log g = 5.838 ± 0.030) were used as independent constraints, as well as partial mode identification based on observed multiplet structures we ascribed to stellar rotation. The optimal model found is remarkably consistent between various analyses with third and fourth generation of sdB models, and also with previously published analysis with second generation sdB models. It corresponds to a sdB with a canonical mass (0.46 ± 0.02 M), rather thin H-He envelope (log q(envl) =-3.75 ± 0.12), and close to He-burning exhaustion (Xcore(C + O) = 0.86 ± 0.05).We also investigate the internal rotation of the star.We find that PG 1219+534 rotates very slowly (Prot = 34.91 ± 0.84 days) and that solid-body rotation is reached at least down to ∼60% of the radius.

Original languageEnglish (US)
Pages (from-to)44-56
Number of pages13
JournalOpen Astronomy
Volume27
Issue number1
DOIs
StatePublished - 2018
Externally publishedYes

Keywords

  • stars: individual: PG 1219+534
  • stars: oscillation
  • stars:interior
  • subdwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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