تقرير
Four ultra-short period eclipsing M-dwarf binaries in the WFCAM Transit Survey
| العنوان: | Four ultra-short period eclipsing M-dwarf binaries in the WFCAM Transit Survey |
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| المؤلفون: | Nefs, S. V., Birkby, J. L., Snellen, I. A. G., Hodgkin, S. T., Pinfield, D. J., Sipocz, B., Kovacs, G., Mislis, D., Saglia, R. P., Koppenhofer, J., Cruz, P., Barrado, D., Martin, E. L., Goulding, N., Stoev, H., Zendejas, J., del Burgo, C., Cappetta, M., Pavlenko, Y. V. |
| سنة النشر: | 2012 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | We report on the discovery of four ultra-short period (P<0.18 days) eclipsing M-dwarf binaries in the WFCAM Transit Survey. Their orbital periods are significantly shorter than of any other known main-sequence binary system, and are all significantly below the sharp period cut-off at P~0.22 days as seen in binaries of earlier type stars. The shortest-period binary consists of two M4 type stars in a P=0.112 day orbit. The binaries are discovered as part of an extensive search for short-period eclipsing systems in over 260,000 stellar lightcurves, including over 10,000 M-dwarfs down to J=18 mag, yielding 25 binaries with P<0.23 days. In a popular paradigm, the evolution of short period binaries of cool main-sequence stars is driven by loss of angular momentum through magnetised winds. In this scheme, the observed P~0.22 day period cut-off is explained as being due to timescales that are too long for lower-mass binaries to decay into tighter orbits. Our discovery of low-mass binaries with significantly shorter orbits implies that either these timescales have been overestimated for M-dwarfs, e.g. due to a higher effective magnetic activity, or that the mechanism for forming these tight M-dwarf binaries is different from that of earlier type main-sequence stars. Comment: 22 pages, 17 figures, 3 tables Accepted for publication in MNRAS |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1111/j.1365-2966.2012.21338.x |
| URL الوصول: | http://arxiv.org/abs/1206.1200 |
| رقم الأكسشن: | edsarx.1206.1200 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1111/j.1365-2966.2012.21338.x |
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