A new bright eclipsing hot subdwarf binary from the ASAS and SuperWASP surveys

Schaffenroth, V.; Geier, S.; Drechsel, H.; Heber, U.; Wils, P.; Østensen, R. H.; Maxted, P. F. L.; di Scala, G.

Abstract

We report the discovery of a bright (mV = 11.6 mag), eclipsing, hot subdwarf binary of spectral type B with a late main sequence companion from the All Sky Automated Survey (ASAS 102322-3737.0). Such systems are called HW Vir stars after the prototype. The lightcurve shows a grazing eclipse and a strong reflection effect. An orbital period of P = 0.13927 d, an inclination of i = 65.86°, a mass ratio q = 0.34, a radial velocity semiamplitude K1 = 81.0 km s-1, and other parameters were derived from a combined spectroscopic and photometric analysis. The short period can only be explained by a common envelope origin of the system. The atmospheric parameters (Teff = 28 400 K, log g = 5.60) are consistent with a core helium-burning star located on the extreme horizontal branch. In agreement with that we derived the most likely sdB mass to be MsdB = 0.46 M⊙, close to the canonical mass of such objects. The companion is a late M-dwarf with a mass of Mcomp = 0.16 M⊙. ASAS 102322-3737.0 is the third brightest of only 12 known HW Virginis systems, which makes it an ideal target for detailed spectroscopic studies and long-term photometric monitoring to search for period variations, e.g., those caused by a substellar companion.

Citation

Schaffenroth, V., Geier, S., Drechsel, H., Heber, U., Wils, P., Østensen, R. H., …di Scala, G. (2013). A new bright eclipsing hot subdwarf binary from the ASAS and SuperWASP surveys. Astronomy & Astrophysics, 553, Article A18. https://doi.org/10.1051/0004-6361/201220929

• Journal Article Type: Article
• Acceptance Date: Mar 1, 2013
• Online Publication Date: Apr 23, 2013
• Publication Date: 2013-05
• Deposit Date: Jun 14, 2023
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 553
• Article Number: A18
• DOI: https://doi.org/10.1051/0004-6361/201220929
• Keywords: Space and Planetary Science; Astronomy and Astrophysics