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A new HW Vir binary from the Palomar Transient Factory. PTF1 J072455.75+125300.3: An eclipsing subdwarf B binary with a M-star companion

Schindewolf, M. and Levitan, D. and Heber, U. and Drechsel, H. and Schaffenroth, V. and Kupfer, T. and Prince, T. (2015) A new HW Vir binary from the Palomar Transient Factory. PTF1 J072455.75+125300.3: An eclipsing subdwarf B binary with a M-star companion. Astronomy and Astrophysics, 580 . Art. No. A117. ISSN 0004-6361.

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We report the discovery of an eclipsing binary – PTF1 J072456+125301– composed of a subdwarf B (sdB) star (g′ = 17.2^m) with a faint companion. Subdwarf B stars are core helium-burning stars, which can be found on the extreme horizontal branch. About half of them reside in close binary systems, but few are known to be eclipsing, for which fundamental stellar parameters can be derived. We conducted an analysis of photometric data and spectra from the Palomar 60′′ and the 200′′ Hale telescope, respectively. A quantitative spectral analysis found an effective temperature of T_(eff) = 33 900 ± 350 K, log g = 5.74 ± 0.08, and log (n_(He)/n_H) = −2.02 ± 0.07, typical for an sdB star. The companion does not contribute to the optical light of the system, except through a distinct reflection effect. From the light curve an orbital period of 0.09980(25) d and a system inclination of 83.56 ± 0.30° were derived. The radial velocity curve yielded an orbital semi-amplitude of K_1 = 95.8 ± 8.1 km s^(-1). The mass for the M-type dwarf companion is 0.155 ± 0.020 M⊙. PTF1 J072456+125301 has similar atmospheric parameters to those of pulsating sdB stars (V346 Hya stars). Therefore it could be a high-priority object for asteroseismology, if pulsations were detected such as in the enigmatic case of NY Vir.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle Paper
Heber, U.0000-0001-7798-6769
Kupfer, T.0000-0002-6540-1484
Prince, T.0000-0002-8850-3627
Additional Information:© 2015 ESO. Article published by EDP Sciences. Received 23 December 2014; Accepted 10 June 2015; Published online 14 August 2015. Based on observations collected at the Palomar Observatory with the 200-inch Hale Telescope, operated by the California institute of Technology, its divisions Caltech Optical Observations, the Jet Propulsion Laboratory (operated for NASA) and Cornell University. Based on observations of the Palomar Transient Factory. The Palomar Transient Factory is a scientific collaboration between the California Institute of Technology, Columbia University, Las Cumbres Observatory, the Lawrence Berkely National Laboratory, the National Energy Research Scientific Computing Center, the University of Oxford, and the Weizmann Institute of Science. T. Kupfer acknowledges support by the Netherlands Research School of Astronomy (NOVA). V. Schaffenroth is supported by the Deutsches Zentrum für Luft- und Raumfahrt (grant 50 OR 1110). This research has made use of ISIS functions provided by ECAP/Remeis Obervatory.
Group:Palomar Transient Factory
Funding AgencyGrant Number
Nederlandse Onderzoekschool voor de Astronomie (NOVA)UNSPECIFIED
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OR 1110
Subject Keywords:binaries: eclipsing – stars: early-type – stars: evolution – stars: fundamental parameters – stars: horizontal-branch –subdwarfs
Record Number:CaltechAUTHORS:20150925-141355852
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Official Citation:A new HW Vir binary from the Palomar Transient Factory - PTF1 J072455.75+125300.3: An eclipsing subdwarf B binary with a M-star companion M. Schindewolf, D. Levitan, U. Heber, H. Drechsel, V. Schaffenroth, T. Kupfer and T. Prince A&A 580 A117 (2015) DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60535
Deposited By: Tony Diaz
Deposited On:25 Sep 2015 21:36
Last Modified:09 Mar 2020 13:18

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