Pulse Timing Discovery of a Three-day Companion to the Hot Subdwarf BPM 36430
Abstract Hot subdwarf B stars are core-helium-burning objects that have undergone envelope stripping, likely by a binary companion. Using high-speed photometry from the Transiting Exoplanet Survey Satellite, we have discovered the hot subdwarf BPM 36430 is a hybrid sdBV rs pulsator exhibiting severa...
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Published in | The Astrophysical journal Vol. 939; no. 1; pp. 57 - 62 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Philadelphia
The American Astronomical Society
01.11.2022
IOP Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | Abstract
Hot subdwarf B stars are core-helium-burning objects that have undergone envelope stripping, likely by a binary companion. Using high-speed photometry from the Transiting Exoplanet Survey Satellite, we have discovered the hot subdwarf BPM 36430 is a hybrid sdBV
rs
pulsator exhibiting several low-amplitude
g
-modes and a strong
p
-mode pulsation. The latter shows a clear, periodic variation in its pulse arrival times. Fits to this phase oscillation imply BPM 36430 orbits a barycenter approximately 10 light-seconds away once every 3.1 days. Using the CHIRON echelle spectrograph on the CTIO 1.5 m telescope, we confirm the reflex motion by detecting a radial-velocity variation with semiamplitude, period, and phase in agreement with the pulse timings. We conclude that a white dwarf companion with minimum mass of ≈0.42
M
⊙
orbits BPM 36430. Our study represents only the second time a companion orbiting a pulsating hot subdwarf or white dwarf has been detected from pulse timings and confirmed with radial velocities. |
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Bibliography: | Stars and Stellar Physics AAS41271 |
ISSN: | 0004-637X 1538-4357 |
DOI: | 10.3847/1538-4357/ac9384 |