PTF1 J082340.04+081936.5: A Hot Subdwarf B Star with a Low-mass White Dwarf Companion in an 87-minute Orbit
Kupfer T, van Roestel J, Brooks J, Geier S, Marsh TR, Groot PJ, Bloemen S, Prince TA, Bellm E, Heber U, Bildsten L, Miller AA, Dyer MJ, Dhillon VS, Green M, Irawati P, Laher RR, Littlefair SP, Shupe DL, Steidel CC, Rattansoon S, Pettini M (2017)
Publication Status: Published
Publication Type: Journal article
Publication year: 2017
Journal
Publisher: IOP PUBLISHING LTD
Book Volume: 835
Article Number: ARTN 131
Journal Issue: 2
DOI: 10.3847/1538-4357/835/2/131
Abstract
We present the discovery of the hot subdwarf B star (sdB) binary PTF1 J082340.04+081936.5. The system has an orbital period of P-orb = 87.49668(1) minutes (0.060761584(10) days), making it the second-most compact sdB binary known. The light. curve shows ellipsoidal variations. Under the assumption that the sdB primary is synchronized with the orbit, we find a mass of = M-sdB =0.45(-0.07)(+0.009) M-circle dot, a companion white dwarf mass of M-WD = 0.46(-0.09)(+0.12)M(circle dot), and a mass ratio of q =M-WD/M(sdB)1.03+(+0.10)(0.08). The future evolution was calculated using the MESA stellar evolution code. Adopting a canonical sdB mass of M-sdB = 0.47 M-circle dot, we find that the sdB still burns helium at the time it will fill its Roche lobe if the orbital period was less than 106 minutes at the exit from the last common envelope (CE) phase. For longer CE exit periods, the sdB will have stopped burning helium and turned into a C/O white dwarf at the time of contact. Comparing the spectroscopically derived log g and T-eff with our MESA models, we find that an sdB model with a hydrogen envelope mass of 5 x 10(-4) M-circle dot matches the measurements at a post-CE age of 94 Myr, corresponding to a post-CE orbital period of 109 minutes, which is close to the limit to start accretion while the sdB is still burning helium.
Authors with CRIS profile
Stephan Geier
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Ulrich Heber
Professur für Astronomie und Astrophysik
Involved external institutions
California Institute of Technology (Caltech)
United States (USA) (US)
University of Sheffield
United Kingdom (GB)
Radboud University Nijmegen
Netherlands (NL)
University of Warwick
United Kingdom (GB)
National Astronomical Research Institute of Thailand
Thailand (TH)
University of California
United States (USA) (US)
United States (USA) (US)
University of Sheffield
United Kingdom (GB)
Radboud University Nijmegen
Netherlands (NL)
University of Warwick
United Kingdom (GB)
National Astronomical Research Institute of Thailand
Thailand (TH)
University of California
United States (USA) (US)
How to cite
APA:
Kupfer, T., van Roestel, J., Brooks, J., Geier, S., Marsh, T.R., Groot, P.J.,... Pettini, M. (2017). PTF1 J082340.04+081936.5: A Hot Subdwarf B Star with a Low-mass White Dwarf Companion in an 87-minute Orbit. Astrophysical Journal, 835(2). https://doi.org/10.3847/1538-4357/835/2/131
MLA:
Kupfer, Thomas, et al. "PTF1 J082340.04+081936.5: A Hot Subdwarf B Star with a Low-mass White Dwarf Companion in an 87-minute Orbit." Astrophysical Journal 835.2 (2017).
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