A rare reflection effect eclipsing sdB+dM binary: 2M 1533+3759
Source: Astrophysics and Space Science, Volume 329, Numbers 1-2, October 2010 , pp. 87-90(4)
Abstract:In this paper, we report a rare reflection effect eclipsing sdB+dM binary, 2M 1533+3759. It is the seventh eclipsing sdB+dM binary that has been discovered to date. This system has an orbital period of 0.16177042 day and a velocity semi-amplitude of 71.1 km s−1. Using a grid of zero-metallicity NLTE model atmospheres, we derived T eff=29250 K, log g=5.58 and [He/H]=−2.37 from spectra taken near the reflection effection minimum. Lightcurve modeling resulted in a system mass ratio of 0.301 and an orbital inclination angle of 86.6°. The derived primary mass for 2M 1533+3759, 0.376±0.055 M ⊙, is significantly lower than the canonical mass (0.48 M ⊙) found for most previously investigated sdB stars. This implies an initial progenitor mass >1.8 M ⊙, at least a main sequence A star and perhaps even one massive enough to undergo non-degenerate helium ignition.
Document Type: Research Article
Affiliations: 1: Department of Astronomy, University of Texas, Austin, TX, 78712, USA, Email: firstname.lastname@example.org 2: Steward Observatory, University of Arizona, Tucson, AZ, 85712, USA 3: Département de Physique, Université de Montréal, Montréal, QC, H3C 3J7, Canada 4: Department of Physics and Astronomy, University of Georgia, Athens, GA, 30602, USA
Publication date: October 2010