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Binaries discovered by the MUCHFUSS project: FBS 0117+396: An sdB+dM binary with a pulsating primary⋆

Østensen, R. H.; Geier, S.; Schaffenroth, V.; Telting, J. H.; Bloemen, S.; Németh, P.; Beck, P. G.; Lombaert, R.; Pápics, P. I.; Tillich, A.; Ziegerer, E.; Fox Machado, L.; Littlefair, S.; Dhillon, V.; Aerts, C.; Heber, U.; Maxted, P. F. L.; Gänsicke, B. T.; Marsh, T. R.

Authors

R. H. Østensen

S. Geier

V. Schaffenroth

J. H. Telting

S. Bloemen

P. Németh

P. G. Beck

R. Lombaert

P. I. Pápics

A. Tillich

E. Ziegerer

L. Fox Machado

S. Littlefair

V. Dhillon

C. Aerts

U. Heber

B. T. Gänsicke

T. R. Marsh



Abstract

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims to discover subdwarf-B stars with massive compact companions such as overmassive white dwarfs (M > 1.0 M⊙), neutron stars or black holes. From the 127 subdwarfs with substantial radial-velocity variations discovered in the initial survey, a number of interesting objects have been selected for extensive follow-up. After an initial photometry run with BUSCA revealed that FBS 0117+396 is photometrically variable both on long and short timescales, we chose it as an auxiliary target during a 6-night multi-color photometry run with Ultracam. Spectroscopy was obtained at a number of observatories in order to determine the binary period and obtain a radial-velocity amplitude. After establishing an orbital period of P  = 0.252 d, and removing the signal associated with the irradiated hemisphere of the M-dwarf companion, we were able to detect ten pulsation periods in the Fourier spectrum of the light curve. Two pulsation modes are found to have short periods of 337 and 379 s, and at least eight modes are found with periods between 45 min and 2.5 h. This establishes that FBS 0117+396 is an sdB+dM reflection binary, in which the primary is a hybrid pulsator, and the first one found with this particular mélange of flavours.

Citation

Østensen, R. H., Geier, S., Schaffenroth, V., Telting, J. H., Bloemen, S., Németh, P., …Marsh, T. R. (2013). Binaries discovered by the MUCHFUSS project: FBS 0117+396: An sdB+dM binary with a pulsating primary⋆. Astronomy & Astrophysics, 559, Article A35. https://doi.org/10.1051/0004-6361/201322022

Journal Article Type Article
Acceptance Date Sep 30, 2013
Online Publication Date Oct 31, 2013
Publication Date 2013-11
Deposit Date Jun 14, 2023
Journal Astronomy & Astrophysics
Print ISSN 0004-6361
Electronic ISSN 1432-0746
Publisher EDP Sciences
Peer Reviewed Peer Reviewed
Volume 559
Article Number A35
DOI https://doi.org/10.1051/0004-6361/201322022
Keywords Space and Planetary Science; Astronomy and Astrophysics