A New Class of Large-amplitude Radial-mode Hot Subdwarf Pulsators

Kupfer, Thomas and Bauer, Evan B. and Burdge, Kevin B. and Bellm, Eric C. and Bildsten, Lars and Fuller, Jim and Hermes, JJ and Kulkarni, Shrinivas R. and Prince, Thomas A. and van Roestel, Jan and Dekany, Richard and Duev, Dmitry A. and Feeney, Michael and Giomi, Matteo and Graham, Matthew J. and Kaye, Stephen and Laher, Russ R. and Masci, Frank J. and Porter, Michael and Riddle, Reed and Shupe, David L. and Smith, Roger M. and Soumagnac, Maayane T. and Szkody, Paula and Ward, Charlotte (2019) A New Class of Large-amplitude Radial-mode Hot Subdwarf Pulsators. The Astrophysical Journal, 878 (2). L35. ISSN 2041-8213

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Abstract

Using high-cadence observations from the Zwicky Transient Facility at low Galactic latitudes, we have discovered a new class of pulsating, hot compact stars. We have found four candidates, exhibiting blue colors (g − r ≤ −0.1 mag), pulsation amplitudes of >5%, and pulsation periods of 200–475 s. Fourier transforms of the light curves show only one dominant frequency. Phase-resolved spectroscopy for three objects reveals significant radial velocity, Teff, and $\mathrm{log}(g)$ variations over the pulsation cycle, which are consistent with large-amplitude radial oscillations. The mean Teff and $\mathrm{log}(g)$ for these stars are consistent with hot subdwarf B (sdB) effective temperatures and surface gravities. We calculate evolutionary tracks using MESA and adiabatic pulsations using GYRE for low-mass, helium-core pre-white dwarfs (pre-WDs) and low-mass helium-burning stars. Comparison of low-order radial oscillation mode periods with the observed pulsation periods show better agreement with the pre-WD models. Therefore, we suggest that these new pulsators and blue large-amplitude pulsators (BLAPs) could be members of the same class of pulsators, composed of young ≈0.25–0.35 M⊙ helium-core pre-WDs.

Item Type: Article
Subjects: Science Global Plos > Physics and Astronomy
Depositing User: Unnamed user with email support@science.globalplos.com
Date Deposited: 03 Jun 2023 09:10
Last Modified: 16 Jan 2024 05:07
URI: http://ebooks.manu2sent.com/id/eprint/1007

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