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

J. -Y. Choi; C. Han; A. Udalski; T. Sumi; B. S. Gaudi; A. Gould; D. P. Bennett; M. Dominik; J. -P. Beaulieu; Y. Tsapras; V. Bozza; F. Abe; I. A. Bond; C. S. Botzler; P. Chote; M. Freeman; A. Fukui; K. Furusawa; Y. Itow; C. H. Ling; K. Masuda; Y. Matsubara; N. Miyake; Y. Muraki; K. Ohnishi; N. J. Rattenbury; To. Saito; D. J. Sullivan; K. Suzuki; W. L. Sweatman; D. Suzuki; S. Takino; P. J. Tristram; K. Wada; P. C. M. Yock; M. K. Szymanski; M. Kubiak; G. Pietrzynski; I. Soszynski; J. Skowron; S. Kozlowski; R. Poleski; K. Ulaczyk; L. Wyrzykowski; P. Pietrukowicz; L. A. Almeida; D. L. DePoy; Subo Dong; E. Gorbikov; F. Jablonski; C. B. Henderson; K. -H. Hwang; J. Janczak; Y. -K. Jung; S. Kaspi; C. -U. Lee; U. Malamud; D. Maoz; D. McGregor; J. A. Munoz; B. -G. Park; H. Park; R. W. Pogge; Y. Shvartzvald; I. -G. Shin; J. C. Yee; K. A. Alsubai; P. Browne; M. J. Burgdorf; S. Calchi Novati; P. Dodds; X. -S. Fang; F. Finet; M. Glitrup; F. Grundahl; S. -H. Gu; S. Hardis; K. Harpsoe; T. C. Hinse; A. Hornstrup; M. Hundertmark; J. Jessen-Hansen; U. G. Jrgensen; Noé Kains; E. Kerins; C. Liebig; M. N. Lund; M. Lundkvist; G. Maier; L. Mancini; M. Mathiasen; M. T. Penny; S. Rahvar; D. Ricci; G. Scarpetta; J. Skottfelt; C. Snodgrass; J. Southworth; J. Surdej; J. Tregloan-Reed; J. Wambsganss; O. Wertz; F. Zimmer; M. D. Albrow; E. Bachelet; V. Batista; S. Brillant; A. Cassan; A. A. Cole; C. Coutures; S. Dieters; D. Dominis Prester; J. Donatowicz; P. Fouque; J. Greenhill; D. Kubas; J. -B. Marquette; J. W. Menzies; K. C. Sahu; M. Zub; D. M. Bramich; K. Horne; I. A. Steele; R. A. Street

doi:10.1088/0004-637X/768/2/129

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

J. -Y. Choi, C. Han^*, A. Udalski, T. Sumi, B. S. Gaudi, A. Gould, D. P. Bennett, M. Dominik, J. -P. Beaulieu, Y. Tsapras, V. Bozza, F. Abe, I. A. Bond, C. S. Botzler, P. Chote, M. Freeman, A. Fukui, K. Furusawa, Y. Itow, C. H. LingK. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, K. Ohnishi, N. J. Rattenbury, To. Saito, D. J. Sullivan, K. Suzuki, W. L. Sweatman, D. Suzuki, S. Takino, P. J. Tristram, K. Wada, P. C. M. Yock, M. K. Szymanski, M. Kubiak, G. Pietrzynski, I. Soszynski, J. Skowron, S. Kozlowski, R. Poleski, K. Ulaczyk, L. Wyrzykowski, P. Pietrukowicz, L. A. Almeida, D. L. DePoy, Subo Dong, E. Gorbikov, F. Jablonski, C. B. Henderson, K. -H. Hwang, J. Janczak, Y. -K. Jung, S. Kaspi, C. -U. Lee, U. Malamud, D. Maoz, D. McGregor, J. A. Munoz, B. -G. Park, H. Park, R. W. Pogge, Y. Shvartzvald, I. -G. Shin, J. C. Yee, K. A. Alsubai, P. Browne, M. J. Burgdorf, S. Calchi Novati, P. Dodds, X. -S. Fang, F. Finet, M. Glitrup, F. Grundahl, S. -H. Gu, S. Hardis, K. Harpsoe, T. C. Hinse, A. Hornstrup, M. Hundertmark, J. Jessen-Hansen, U. G. Jrgensen, Noé Kains, E. Kerins, C. Liebig, M. N. Lund, M. Lundkvist, G. Maier, L. Mancini, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, J. Skottfelt, C. Snodgrass, J. Southworth, J. Surdej, J. Tregloan-Reed, J. Wambsganss, O. Wertz, F. Zimmer, M. D. Albrow, E. Bachelet, V. Batista, S. Brillant, A. Cassan, A. A. Cole, C. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouque, J. Greenhill, D. Kubas, J. -B. Marquette, J. W. Menzies, K. C. Sahu, M. Zub, D. M. Bramich, K. Horne, I. A. Steele, R. A. Street

^*Corresponding author for this work

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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.

Original language	English
Article number	129
Number of pages	7
Journal	Astrophysical Journal
Volume	768
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/768/2/129
Publication status	Published - 10 May 2013

Keywords

Binaries: general
Gravitational lensing: micro
Gravitational lens
Extrasolar planets
Galactic bulge
Systems
Events
Search
Stars

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10.1088/0004-637X/768/2/129

Dominik_2013_AJ_Microlensing
© 2013. The American Astronomical Society. All rights reserved.
Final published version, 1.64 MB

Astrophysics at St Andrews:2012 - 2014: Astrophysics at St Andrews: 2012 - 2014
Horne, K. D. (PI)
Science & Technology Facilities Council
1/10/11 → 31/03/12
Project: Standard

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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., ... Street, R. A. (2013). Microlensing discovery of a population of very tight, very low mass binary brown dwarfs. Astrophysical Journal, 768(2), Article 129. https://doi.org/10.1088/0004-637X/768/2/129

@article{1cc1fed23d6d493ab0f0b71173569e51,

title = "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 (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.",

keywords = "Binaries: general, Gravitational lensing: micro, Gravitational lens, Extrasolar planets, Galactic bulge, Systems, Events, Search, Stars",

author = "Choi, {J. -Y.} and C. Han and A. Udalski and T. Sumi and Gaudi, {B. S.} and A. Gould and Bennett, {D. P.} and M. Dominik and Beaulieu, {J. -P.} and Y. Tsapras and V. Bozza and F. Abe and Bond, {I. A.} and Botzler, {C. S.} and P. Chote and M. Freeman and A. Fukui and K. Furusawa and Y. Itow and Ling, {C. H.} and K. Masuda and Y. Matsubara and N. Miyake and Y. Muraki and K. Ohnishi and Rattenbury, {N. J.} and To. Saito and Sullivan, {D. J.} and K. Suzuki and Sweatman, {W. L.} and D. Suzuki and S. Takino and Tristram, {P. J.} and K. Wada and Yock, {P. C. M.} and Szymanski, {M. K.} and M. Kubiak and G. Pietrzynski and I. Soszynski and J. Skowron and S. Kozlowski and R. Poleski and K. Ulaczyk and L. Wyrzykowski and P. Pietrukowicz and Almeida, {L. A.} and DePoy, {D. L.} and Subo Dong and E. Gorbikov and F. Jablonski and Henderson, {C. B.} and Hwang, {K. -H.} and J. Janczak and Jung, {Y. -K.} and S. Kaspi and Lee, {C. -U.} and U. Malamud and D. Maoz and D. McGregor and Munoz, {J. A.} and Park, {B. -G.} and H. Park and Pogge, {R. W.} and Y. Shvartzvald and Shin, {I. -G.} and Yee, {J. C.} and Alsubai, {K. A.} and P. Browne and Burgdorf, {M. J.} and {Calchi Novati}, S. and P. Dodds and Fang, {X. -S.} and F. Finet and M. Glitrup and F. Grundahl and Gu, {S. -H.} and S. Hardis and K. Harpsoe and Hinse, {T. C.} and A. Hornstrup and M. Hundertmark and J. Jessen-Hansen and Jrgensen, {U. G.} and No{\'e} Kains and E. Kerins and C. Liebig and Lund, {M. N.} and M. Lundkvist and G. Maier and L. Mancini and M. Mathiasen and Penny, {M. T.} 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 Albrow, {M. D.} and E. Bachelet and V. Batista and S. Brillant and A. Cassan and Cole, {A. A.} and C. Coutures and S. Dieters and Prester, {D. Dominis} and J. Donatowicz and P. Fouque and J. Greenhill and D. Kubas and Marquette, {J. -B.} and Menzies, {J. W.} and Sahu, {K. C.} and M. Zub and Bramich, {D. M.} and K. Horne and Steele, {I. A.} and Street, {R. A.}",

note = "Work by C. Han was supported by the research grant of Chungbuk National University in 2011. The OGLE project has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 246678. The MOA experiment was supported by grants JSPS22403003 and JSPS23340064. This work is based in part on data collected by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla Observatory, which is operated based on a grant from the Danish Natural Science Foundation (FNU). The MiNDSTEp monitoring campaign is powered by ARTEMiS (Dominik et al. 2008). M.H. acknowledges support by the German Research Foundation (DFG). D.R. (boursier FRIA), F.F. (boursier ARC), and J. Surdej acknowledge support from the Communaut{\'e} fran{\c c}aise de Belgique—Actions de recherche concert{\'e}es—Acad{\'e}mie universitaire Wallonie-Europe. K.A., D.M.B., M.D., K.H., M.H., C.L., C.S., R.A.S., and Y.T. are thankful to the Qatar National Research Fund (QNRF), member of the Qatar Foundation, for support by grant NPRP 09-476-1-078. C.S. has received funding from FP7/2007-2013 under grant agreement No. 268421. K.H. is supported by a Royal Society Leverhulme Trust Senior Research Fellowship. A.G. and B.S.G. acknowledge support from NSF AST-1103471. B.S.G., A.G., and R.W.P. acknowledge support from NASA grant NNX12AB99G. Work by J.C.Y. is supported by a National Science Foundation Graduate Research Fellowship under grant No. 2009068160. S.D.'s research was performed under contract with the California Institute of Technology funded by NASA through the Sagan Fellowship Program. T.S. was supported by the grant JSPS23340044. Y.M. acknowledges support from JSPS grants JSPS23540339 and JSPS19340058. T.C.H. and C.U.L. acknowledge the support of KASI grant 2012-1-410-02 and KRCF.",

year = "2013",

month = may,

day = "10",

doi = "10.1088/0004-637X/768/2/129",

language = "English",

volume = "768",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2",

}

Choi, J-Y, Han, C, Udalski, A, Sumi, T, Gaudi, BS, Gould, A, Bennett, DP, Dominik, M, Beaulieu, J-P, 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, Calchi Novati, S, 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, Jrgensen, 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, Cole, AA, 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 2013, 'Microlensing discovery of a population of very tight, very low mass binary brown dwarfs', Astrophysical Journal, vol. 768, no. 2, 129. https://doi.org/10.1088/0004-637X/768/2/129

TY - JOUR

T1 - Microlensing discovery of a population of very tight, very low mass binary brown dwarfs

AU - Choi, J. -Y.

AU - Han, C.

AU - Udalski, A.

AU - Sumi, T.

AU - Gaudi, B. S.

AU - Gould, A.

AU - Bennett, D. P.

AU - Dominik, M.

AU - Beaulieu, J. -P.

AU - Tsapras, Y.

AU - Bozza, V.

AU - Abe, F.

AU - Bond, I. A.

AU - Botzler, C. S.

AU - Chote, P.

AU - Freeman, M.

AU - Fukui, A.

AU - Furusawa, K.

AU - Itow, Y.

AU - Ling, C. H.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Miyake, N.

AU - Muraki, Y.

AU - Ohnishi, K.

AU - Rattenbury, N. J.

AU - Saito, To.

AU - Sullivan, D. J.

AU - Suzuki, K.

AU - Sweatman, W. L.

AU - Suzuki, D.

AU - Takino, S.

AU - Tristram, P. J.

AU - Wada, K.

AU - Yock, P. C. M.

AU - Szymanski, M. K.

AU - Kubiak, M.

AU - Pietrzynski, G.

AU - Soszynski, I.

AU - Skowron, J.

AU - Kozlowski, S.

AU - Poleski, R.

AU - Ulaczyk, K.

AU - Wyrzykowski, L.

AU - Pietrukowicz, P.

AU - Almeida, L. A.

AU - DePoy, D. L.

AU - Dong, Subo

AU - Gorbikov, E.

AU - Jablonski, F.

AU - Henderson, C. B.

AU - Hwang, K. -H.

AU - Janczak, J.

AU - Jung, Y. -K.

AU - Kaspi, S.

AU - Lee, C. -U.

AU - Malamud, U.

AU - Maoz, D.

AU - McGregor, D.

AU - Munoz, J. A.

AU - Park, B. -G.

AU - Park, H.

AU - Pogge, R. W.

AU - Shvartzvald, Y.

AU - Shin, I. -G.

AU - Yee, J. C.

AU - Alsubai, K. A.

AU - Browne, P.

AU - Burgdorf, M. J.

AU - Calchi Novati, S.

AU - Dodds, P.

AU - Fang, X. -S.

AU - Finet, F.

AU - Glitrup, M.

AU - Grundahl, F.

AU - Gu, S. -H.

AU - Hardis, S.

AU - Harpsoe, K.

AU - Hinse, T. C.

AU - Hornstrup, A.

AU - Hundertmark, M.

AU - Jessen-Hansen, J.

AU - Jrgensen, U. G.

AU - Kains, Noé

AU - Kerins, E.

AU - Liebig, C.

AU - Lund, M. N.

AU - Lundkvist, M.

AU - Maier, G.

AU - Mancini, L.

AU - Mathiasen, M.

AU - Penny, M. T.

AU - Rahvar, S.

AU - Ricci, D.

AU - Scarpetta, G.

AU - Skottfelt, J.

AU - Snodgrass, C.

AU - Southworth, J.

AU - Surdej, J.

AU - Tregloan-Reed, J.

AU - Wambsganss, J.

AU - Wertz, O.

AU - Zimmer, F.

AU - Albrow, M. D.

AU - Bachelet, E.

AU - Batista, V.

AU - Brillant, S.

AU - Cassan, A.

AU - Cole, A. A.

AU - Coutures, C.

AU - Dieters, S.

AU - Prester, D. Dominis

AU - Donatowicz, J.

AU - Fouque, P.

AU - Greenhill, J.

AU - Kubas, D.

AU - Marquette, J. -B.

AU - Menzies, J. W.

AU - Sahu, K. C.

AU - Zub, M.

AU - Bramich, D. M.

AU - Horne, K.

AU - Steele, I. A.

AU - Street, R. A.

N1 - Work by C. Han was supported by the research grant of Chungbuk National University in 2011. The OGLE project has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 246678. The MOA experiment was supported by grants JSPS22403003 and JSPS23340064. This work is based in part on data collected by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla Observatory, which is operated based on a grant from the Danish Natural Science Foundation (FNU). The MiNDSTEp monitoring campaign is powered by ARTEMiS (Dominik et al. 2008). M.H. acknowledges support by the German Research Foundation (DFG). D.R. (boursier FRIA), F.F. (boursier ARC), and J. Surdej acknowledge support from the Communauté française de Belgique—Actions de recherche concertées—Académie universitaire Wallonie-Europe. K.A., D.M.B., M.D., K.H., M.H., C.L., C.S., R.A.S., and Y.T. are thankful to the Qatar National Research Fund (QNRF), member of the Qatar Foundation, for support by grant NPRP 09-476-1-078. C.S. has received funding from FP7/2007-2013 under grant agreement No. 268421. K.H. is supported by a Royal Society Leverhulme Trust Senior Research Fellowship. A.G. and B.S.G. acknowledge support from NSF AST-1103471. B.S.G., A.G., and R.W.P. acknowledge support from NASA grant NNX12AB99G. Work by J.C.Y. is supported by a National Science Foundation Graduate Research Fellowship under grant No. 2009068160. S.D.'s research was performed under contract with the California Institute of Technology funded by NASA through the Sagan Fellowship Program. T.S. was supported by the grant JSPS23340044. Y.M. acknowledges support from JSPS grants JSPS23540339 and JSPS19340058. T.C.H. and C.U.L. acknowledge the support of KASI grant 2012-1-410-02 and KRCF.

PY - 2013/5/10

Y1 - 2013/5/10

N2 - 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.

AB - 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.

KW - Binaries: general

KW - Gravitational lensing: micro

KW - Gravitational lens

KW - Extrasolar planets

KW - Galactic bulge

KW - Systems

KW - Events

KW - Search

KW - Stars

U2 - 10.1088/0004-637X/768/2/129

DO - 10.1088/0004-637X/768/2/129

M3 - Article

SN - 0004-637X

VL - 768

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 129

ER -

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

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Keywords

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Astrophysics at St Andrews:2012 - 2014: Astrophysics at St Andrews: 2012 - 2014

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