BINARIES DISCOVERED BY THE MUCHFUSS PROJECT: SDSS J08205+0008-AN ECLIPSING SUBDWARF B BINARY WITH A BROWN DWARF COMPANION
- Dr. Remeis-Observatory and ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nuernberg, Sternwartstr. 7, 96049 Bamberg (Germany)
- Institute of Astronomy, K.U. Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium)
- Astrophysics Group, Keele University, Staffordshire, ST5 5BG (United Kingdom)
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States)
- Department of Physics, University of Warwick, Conventry CV4 7AL (United Kingdom)
- Centre of Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom)
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 ({approx_equal}0.068 M{sub sun}) 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.
- OSTI ID:
- 21562735
- Journal Information:
- Astrophysical Journal Letters, Vol. 731, Issue 2; Other Information: DOI: 10.1088/2041-8205/731/2/L22; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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