Binaries discovered by the Muchfuss Project : SDSS J08205+0008— an eclipsing subdwarf B binary with a brown dwarf companion
Geier, S., Schaffenroth, V., Drechsel, H., Heber, U., Kupfer, T., Tillich, A., Østensen, R. H., Smolders, K., Degroote, P., Maxted, P. F. L., Barlow, B. N., Gaensicke, B. T., Marsh, T. R. and Napiwotzki, Ralf. (2011) Binaries discovered by the Muchfuss Project : SDSS J08205+0008— an eclipsing subdwarf B binary with a brown dwarf companion. The Astrophysical Journal, Vol.731 (No.2). L22. ISSN 0004-637XFull text not available from this repository.
Official URL: http://dx.doi.org/10.1088/2041-8205/731/2/L22
Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours to a few days. The enormous mass loss required to remove the hydrogen envelope of the red-giant progenitor almost entirely can be explained by common envelope ejection. A rare subclass of these binaries are the eclipsing HW Vir binaries where the sdB is orbited by a dwarf M star. Here, we report the discovery of an HW Vir system in the course of the MUCHFUSS project. A most likely substellar object (similar or equal to 0.068M(circle dot)) was found to orbit the hot subdwarf J08205+0008 with a period of 0.096 days. Since the eclipses are total, the system parameters are very well constrained. J08205+0008 has the lowest unambiguously measured companion mass yet found in a subdwarf B binary. This implies that the most likely substellar companion has not only survived the engulfment by the red-giant envelope, but also triggered its ejection and enabled the sdB star to form. The system provides evidence that brown dwarfs may indeed be able to significantly affect late stellar evolution.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Divisions:||Faculty of Science > Physics|
|Library of Congress Subject Headings (LCSH):||Double stars, Double stars -- Spectra, Brown dwarf stars, Horizontal branch stars, Stars|
|Journal or Publication Title:||The Astrophysical Journal|
|Publisher:||Institute of Physics Publishing, Inc.|
|Official Date:||20 April 2011|
|Funder:||Deutsche Forschungsgemeinschaft (DFG), European Research Council (ERC), Katholieke Universiteit te Leuven (1970- ) (KUL)|
|Grant number:||HE1356/45-1 (DFG), HE1356/49-1 (DFG), 227224 (ERC), GOA/2008/04 (KUL)|
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