The orbits of subdwarf B + main-sequence binaries I: The sdB+G0 system PG 1104+243
The orbits of subdwarf B + main-sequence binaries I: The sdB+G0 system PG 1104+243
复制标题
亚矮星 B 主序双星 I 的轨道：sdB G0 系统 PG 1104 243
DOI：
10.1051/0004-6361/201219723
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发表时间：
2012
影响因子：
6.5
通讯作者：
T. Rauch
中科院分区：
文献类型：
--
作者：
J. Vos;R. Ostensen;P. Degroote;K. D. Smedt;E. Green;U. Heber;H. Winckel;B. Acke;S. Bloemen;P. Cat;K. Exter;P. Lampens;R. Lombaert;T. Masseron;J. Menu;P. Neyskens;G. Raskin;K. Smolders;A. Tkachenko;E. Ringat;T. Rauch
Context. The predicted orbital period histogram of a subdwarf B (sdB) population is bimodal with a peak at short ( 250 days) periods. Observationally, however, there are many short-period sdB systems known, but only very few long-period sdB binaries are identified. As these predictions are based on poorly understood binary interaction processes, it is of prime importance to confront the predictions to well constrained observational data. We therefore initiated a monitoring program to find and characterize long-period sdB stars. Aims. In this contribution we aim to determine the absolute dimensions of the long-period binary system PG 1104+243 consisting of an sdB and a main-sequence (MS) component, and determine its evolution history. Methods. High-resolution spectroscopy time-series were obtained with HERMES at the Mercator telescope at La Palma, and analyzed to determine the radial velocities of both the sdB and MS components. Photometry from the literature was used to construct the spectral energy distribution (SED) of the binary. Atmosphere models were used to fit this SED and determine the surface gravity and temperature of both components. The gravitational redshift provided an independent confirmation of the surface gravity of the sdB component. Results. An orbital period of 753 ± 3 d and a mass ratio of q = 0.637 ± 0.015 were found for PG 1104+243 from the radial velocity curves. The sdB component has an effective temperature of Teff = 33 500 ± 1200 K and a surface gravity of log g = 5.84 ± 0.08 dex, while the cool companion is found to be a G-type star with Teff = 5930 ± 160 K and log g = 4.29 ± 0.05 dex. When a canonical mass
