Microlensing Discovery of a Population of Very Tight, Very Low-mass Binary Brown Dwarfs
Abstract
Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs are poorly understood. The multiplicity properties and minimum mass of the brown-dwarf mass function provide critical empirical diagnostics of these mechanisms. We present the discovery via gravitational microlensing of two very low-mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 Msun and 0.034 Msun, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field brown-dwarf binaries known. The discovery of a population of such binaries indicates that brown dwarf binaries can robustly form at least down to masses of ~0.02 Msun. Future microlensing surveys will measure a mass-selected sample of brown-dwarf binary systems, which can then be directly compared to similar samples of stellar binaries.
Keywords
Cite
@article{arxiv.1302.4169,
title = {Microlensing Discovery of a Population of Very Tight, Very Low-mass Binary Brown Dwarfs},
author = {J. -Y. Choi and C. Han and A. Udalski and T. Sumi and B. S. Gaudi and A. Gould and D. P. Bennett and M. Dominik and J. -P. Beaulieu and Y. Tsapras and V. Bozza and F. Abe and I. A. Bond and C. S. Botzler and P. Chote and M. Freeman and A. Fukui and K. Furusawa and Y. Itow and C. H. Ling and K. Masuda and Y. Matsubara and N. Miyake and Y. Muraki and K. Ohnishi and N. J. Rattenbury and To. Saito and D. J. Sullivan and K. Suzuki and W. L. Sweatman and D. Suzuki and S. Takino and P. J. Tristram and K. Wada and P. C. M. Yock and M. K. Szymański and M. Kubiak and G. Pietrzyński and I. Soszyński and J. Skowron and S. Kozłowski and R. Poleski and K. Ulaczyk and Ł. Wyrzykowski and P. Pietrukowicz and L. A. Almeida and D. L. DePoy and Subo Dong and E. Gorbikov and F. Jablonski and C. B. Henderson and K. -H. Hwang and J. Janczak and Y. -K. Jung and S. Kaspi and C. -U. Lee and U. Malamud and D. Maoz and D. McGregor and J. A. Munoz and B. -G. Park and H. Park and R. W. Pogge and Y. Shvartzvald and I. -G. Shin and J. C. Yee and K. A. Alsubai and P. Browne and M. J. Burgdorf and S. Calchi Novati and P. Dodds and X. -S. Fang and F. Finet and M. Glitrup and F. Grundahl and S. -H. Gu and S. Hardis and K. Harpsøe and T. C. Hinse and A. Hornstrup and M. Hundertmark and J. Jessen-Hansen and U. G. Jørgensen and N. Kains and E. Kerins and C. Liebig and M. N. Lund and M. Lundkvist and G. Maier and L. Mancini and M. Mathiasen and M. T. Penny and S. Rahvar and D. Ricci and G. Scarpetta and J. Skottfelt and C. Snodgrass and J. Southworth and J. Surdej and J. Tregloan-Reed and J. Wambsganss and O. Wertz and F. Zimmer and M. D. Albrow and E. Bachelet and V. Batista and S. Brillant and A. Cassan and A. A. Cole and C. Coutures and S. Dieters and D. Dominis Prester and J. Donatowicz and P. Fouqué and J. Greenhill and D. Kubas and J. -B. Marquette and J. W. Menzies and K. C. Sahu and M. Zub and D. M. Bramich and K. Horne and I. A. Steele and R. A. Street},
journal= {arXiv preprint arXiv:1302.4169},
year = {2015}
}
Comments
7 pages, 5 figures, 3 tables, ApJ submitted