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

journal contribution
posted on 2023-05-17, 21:36 authored by Choi, J-Y, Han, C, Udalski, A, Sumi, T, Gaudi, BS, Gould, A, Bennett, DP, Dominik, M, Jean-Philippe BeaulieuJean-Philippe Beaulieu, Tsapras, Y, Bozza, V, Abe, F, Bond, IA, Botzler, CS, Chote, P, Freeman, M, Fukui, A, Furusawa, K, Itow, Y, Ling, CH, Masuda, K, Matsubara, Y, Miyake, N, Muraki, Y, Ohnishi, K, Rattenbury, NJ, Saito, T, Sullivan, DJ, Suzuki, K, Sweatman, WL, Suzuki, D, Takino, S, Tristram, PJ, Wada, K, Yock, PCM, Szymanski, MK, Kubiak, M, Pietrzynski, G, Soszynski, I, Skowron, J, Kozlowski, S, Poleski, R, Ulaczyk, K, Wyrzykowski, L, Pietrukowicz, P, Almeida, LA, DePoy, DL, Dong, S, Gorbikov, E, Jablonski, F, Henderson, CB, Hwang, K-H, Janczak, J, Jung, Y-K, Kaspi, S, Lee, C-U, Malamud, U, Maoz, D, McGregor, D, Munoz, JA, Park, B-G, Park, H, Pogge, RW, Shvartzvald, Y, Shin, I-G, Yee, JC, Alsubai, KA, Browne, P, Burgdorf, MJ, Novati, SC, Dodds, P, Fang, X-S, Finet, F, Glitrup, M, Grundahl, F, Gu, S-H, Hardis, S, Harpsoe, K, Hinse, TC, Hornstrup, A, Hundertmark, M, Jessen-Hansen, J, Jorgensen, UG, Kains, N, Kerins, E, Liebig, C, Lund, MN, Lundkvist, M, Maier, G, Mancini, L, Mathiasen, M, Penny, MT, Rahvar, S, Ricci, D, Scarpetta, G, Skottfelt, J, Snodgrass, C, Southworth, J, Surdej, J, Tregloan-Reed, J, Wambsganss, J, Wertz, O, Zimmer, F, Albrow, MD, Bachelet, E, Batista, V, Brillant, S, Cassan, A, Andrew ColeAndrew Cole, Coutures, C, Dieters, S, Prester, DD, Donatowicz, J, Fouque, P, Greenhill, J, Kubas, D, Marquette, J-B, Menzies, JW, Sahu, KC, Zub, M, Bramich, DM, Horne, K, Steele, IA, Street, RA
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.

History

Publication title

The Astrophysical Journal

Volume

768

Article number

129

Number

129

Pagination

1-7

ISSN

0004-637X

Department/School

School of Natural Sciences

Publisher

Univ Chicago Press

Place of publication

1427 E 60Th St, Chicago, USA, Il, 60637-2954

Rights statement

Copyright 2013 The American Astronomical Society

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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