期刊
OPEN ASTRONOMY
卷 27, 期 1, 页码 80-90出版社
DE GRUYTER POLAND SP ZOO
DOI: 10.1515/astro-2018-0011
关键词
subdwarfs; binaries: eclipsing; stars: early-type; stars: evolution; stars: fundamental parameters; stars: horizontal-branch
资金
- STFC [ST/K002783/1, ST/F012276/1, ST/M006492/1, ST/P000495/1, ST/P00721X/1, ST/H008500/1] Funding Source: UKRI
HW Vir systems are rare eclipsing binary systems including a subdwarf B star (sdB) with a faint companion, mostly M-dwarfs. Up to now, 19 HW Vir systems have been published, three of them with substellar companions. We report the spectroscopic as well as photometric observation of the eclipsing sdB binary PTF1 J011339.09+225739.1 (PTF1 J0113) in a close (a=0.722 +/- 0.023 R-circle dot), short period (P = 0.0933731(3)d) orbit. A quantitative spectral analysis of the sdB yields T-eff =29280 +/- 720 K, log(g)=5.77 +/- 0.09 dex, and log(y)=-2.32 +/- 0.12. The circular orbital velocity of the sdB of K-1 =74.2 +/- 1.7 km s(-1) is derived from the radial velocity curve. Except for the strong reflection effect, no other light contribution of the companion could be detected. The light curves - recorded with ULTRACAM - were analyzed using the Wilson-Devinney code. We find an inclination angle of i=79.88 +/- 0.18 degrees. Because our first attempts to determine q failed, we calculated large grids of synthetic lightcurves for several mass ratios. Because of degeneracy, good solutions for different mass ratios were found - the one at q = 0.24 is consistent with the sdB's canonical mass (M-sdB = 0.47 M-circle dot). Accordingly, the mass of the companion is M-2=0.112 +/- 0.003 M-circle dot. The radii of the two components were also derived: R-sdB=0.178 +/- 0.006 R-circle dot and R-2 = 0.158 +/- 0.009 R-circle dot. Thus, the results for the secondary are consistent with an M-dwarf as secondary.
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