Characterizing low-mass binaries from observation of long-timescale caustic-crossing gravitational microlensing events
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journal contribution
posted on 2025-01-15, 01:00authored byI-G Shin, C Han, J-Y Choi, A Udalski, T Sumi, A Gould, V Bozza, M Dominik, P Fouque, K Horne, MK Szymanski, M Kubiak, I Soszynski, G Pietrzynski, R Poleski, K Ulaczyk, P Pietrukowicz, S Kozlowski, J Skowron, L Wyrzykowski, F Abe, DP Bennett, IA Bond, CS Botzler, P Chote, M Freeman, A Fukui, K Furusawa, Y Itow, S Kobara, CH Ling, K Masuda, Y Matsubara, N Miyake, Y Muraki, K Ohmori, K Ohnishi, NJ Rattenbury, To Saito, DJ Sullivan, D Suzuki, K Suzuki, WL Sweatman, S Takino, PJ Tristram, K Wada, PCM Yock, DM Bramich, C Snodgrass, IA Steele, RA Street, Y Tsapras, KA Alsubai, P Browne, MJ Burgdorf, S Calchi Novati, P Dodds, S Dreizler, X-S Fang, F Grundahl, C-H Gu, S Hardis, K Harpsoe, TC Hinse, A Hornstrup, M Hundertmark, J Jessen-Hansen, UG Jorgensen, N Kains, E Kerins, C Liebig, M Lund, M Lunkvist, L Mancini, M Mathiasen, MT Penny, S Rahvar, D Ricci, G Scarpetta, J Skottfelt, J Southworth, J Surdej, J Tregloan-Reed, J Wambsganss, O Wetz, LA Almeida, V Batista, G Christie, DL DePloy, Subo Dong, BS Gaudi, C Henderson, F Jablonski, C-U Lee, J McCormick, D McGregor, D Moorhouse, T Natusch, H Ngan, S-Y Park, RW Pogge, T-G Tan, G Thornely, JC Yee, MD Albrow, E Bachelet, Jean-Philippe BeaulieuJean-Philippe Beaulieu, S Brillant, A Cassan, Andrew ColeAndrew Cole, E Corrales, C Coutures, S Dieters, D Dominis Prester, J Donatowicz, J Greenhill, D Kubas, J-B Marquette, JW Menzies, KC Sahu, M Zub
Despite the astrophysical importance of binary star systems, detections are limited to those located in small ranges of separations, distances, and masses and thus it is necessary to use a variety of observational techniques for a complete view of stellar multiplicity across a broad range of physical parameters. In this paper, we report the detections and measurements of two binaries discovered from observations of microlensing events MOA-2011-BLG-090 and OGLE-2011-BLG-0417. Determinations of the binary masses are possible by simultaneously measuring the Einstein radius and the lens parallax. The measured masses of the binary components are 0.43 M☉ and 0.39 M☉ for MOA-2011-BLG-090 and 0.57 M☉ and 0.17 M☉ for OGLE-2011-BLG-0417 and thus both lens components of MOA-2011-BLG-090 and one component of OGLE-2011-BLG-0417 are M dwarfs, demonstrating the usefulness of microlensing in detecting binaries composed of low-mass components. From modeling of the light curves considering full Keplerian motion of the lens, we also measure the orbital parameters of the binaries. The blended light of OGLE-2011-BLG-0417 comes very likely from the lens itself, making it possible to check the microlensing orbital solution by follow-up radial-velocity observation. For both events, the caustic-crossing parts of the light curves, which are critical for determining the physical lens parameters, were resolved by high-cadence survey observations and thus it is expected that the number of microlensing binaries with measured physical parameters will increase in the future.
History
Publication title
The Astrophysical Journal
Volume
755
Issue
2
Article number
91
Number
91
Pagination
1-10
ISSN
0004-637X
Department/School
School of Natural Sciences, Physics
Publisher
IOP Science
Publication status
Published
Place of publication
1427 E 60Th St, Chicago, USA, Il, 60637-2954
Rights statement
Copyright 2012 The American Astronomical Society
Socio-economic Objectives
280120 Expanding knowledge in the physical sciences