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Microlensing discovery of a population of very tight, very low mass binary brown dwarfs

Choi, J.-Y.; Han, C.; Udalski, A.; Sumi, T.; Gaudi, B. S.; Gould, A.; Bennett, D. P.; Dominik, M.; Beaulieu, J.-P.; Tsapras, Y.; Bozza, V.; Abe, F.; Bond, I. A.; Botzler, C. S.; Chote, P.; Freeman, M.; Fukui, A.; Furusawa, K.; Itow, Y.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Suzuki, K.; Sweatman, W. L.; Suzuki, D.; Takino, S.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Skowron, J.; Kozłowski, S.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Pietrukowicz, P.; Almeida, L. A.; DePoy, D. L.; Dong, Subo; Gorbikov, E.; Jablonski, F.; Henderson, C. B.; Hwang, K.-H.; Janczak, J.; Jung, Y.-K.; Kaspi, S.; Lee, C.-U.; Malamud, U.; Maoz, D.; McGregor, D.; Muñoz, J. A.; Park, B.-G.; Park, H.; Pogge, R. W.; Shvartzvald, Y.; Shin, I.-G.; Yee, J. C.; Alsubai, K. A.; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Fang, X.-S.; Finet, F.; Glitrup, M.; Grundahl, F.; Gu, S.-H.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Hornstrup, A.; Hundertmark, M.; Jessen-Hansen, J.; Jrgensen, U. G.; Kains, N.; Kerins, E.; Liebig, C.; Lund, M. N.; Lundkvist, M.; Maier, G.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Southworth, J.; Surdej, J.; Tregloan-Reed, J.; Wambsganss, J.; Wertz, O.; Zimmer, F.; Albrow, M. D.; Bachelet, E.; Batista, V.; Brillant, S.; Cassan, A.; Cole, A. A.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Kubas, D.; Marquette, J.-B.; Menzies, J. W.; Sahu, K. C.; Zub, M.; Bramich, D. M.; Horne, K.; Steele, I. A. and Street, R. A. (2013). Microlensing discovery of a population of very tight, very low mass binary brown dwarfs. Astrophysical Journal, 768(2), article no. 129.

DOI (Digital Object Identifier) Link: https://doi.org/10.1088/0004-637X/768/2/129
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Abstract

Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs (BDs) are poorly understood. The multiplicity properties and minimum mass of the BD 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 M and 0.034 M , and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field BD binaries known. The discovery of a population of such binaries indicates that BD binaries can robustly form at least down to masses of ~0.02 M . Future microlensing surveys will measure a mass-selected sample of BD binary systems, which can then be directly compared to similar samples of stellar binaries.

Item Type: Journal Item
Copyright Holders: 2013 The American Astronomical Society
ISSN: 1538-4357
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNPRP 09-476-1-078Qatar National Research Fund (QNRF)
FP7/2007-2013268421EU
Extra Information: 7 pp.
Keywords: binaries; gravitational lensing
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Centre for Electronic Imaging (CEI)
Space
Item ID: 43048
Depositing User: Colin Snodgrass
Date Deposited: 21 May 2015 15:14
Last Modified: 07 Dec 2018 10:31
URI: http://oro.open.ac.uk/id/eprint/43048
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