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Binary microlensing event OGLE-2009-BLG-020 gives verifiable mass, distance, and orbit predictions

journal contribution
posted on 2023-05-17, 08:14 authored by Skowron, J, Udalski, A, Gould, A, Dong, S, Monard, LAG, Han, C, Nelson, CR, McCormick, J, Moorhouse, D, Thornley, G, Maury, A, Bramich, DM, Greenhill, J, Kozlowski, S, Bond, I, Poleski, R, Wyrzykowski, L, Ulaczyk, K, Kubiak, M, Szymanski, MK, Pietrzynski, G, Soszynski, I, Gaudi, BS, Yee, JC, Hung, LW, Pogge, RW, DePoy, DL, Lee, CU, Park, BG, Allen, W, Mallia, F, Drummond, J, Bolt, G, Allan, A, Browne, P, Clay, N, Dominik, M, Fraser, S, Horne, K, Kains, N, Mottram, C, Snodgrass, C, Steele, I, Street, RA, Tsapras, Y, Abe, F, Bennett, DP, Botzler, CS, Douchin, D, Freeman, M, Fukui, A, Furusawa, K, Hayashi, F, Hearnshaw, JB, Hosaka, S, Itow, Y, Kamiya, K, Kilmartin, PM, Korpela, A, Lin, W, Ling, CH, Makita, S, Masuda, K, Matsubara, Y, Muraki, Y, Nagayama, T, Miyake, N, Nishimoto, K, Ohnishi, K, Perrott, YC, Rattenbury, N, Saito, To, Skuljan, L, Sullivan, DJ, Sumi, T, Suzuki, D, Sweatman, WL, Tristram, PJ, Wada, K, Yock, PCM, Beaulieu, JP, Fouque, P, Albrow, MD, Batista, V, Brillant, S, Caldwell, JAR, Cassan, A, Andrew ColeAndrew Cole, Cook, KH, Coutures, CH, Dieters, S, Dominis Prester, D, Donatowicz, J, Kane, SR, Kubas, D, Marquette, JB, Martin, R, Menzies, J, Sahu, KC, Wambsganss, J, Williams, A, Zub, M
We present the first example of binary microlensing for which the parameter measurements can be verified (or contradicted) by future Doppler observations. This test is made possible by a confluence of two relatively unusual circumstances. First, the binary lens is bright enough (I = 15.6) to permit Doppler measurements. Second, we measure not only the usual seven binary-lens parameters, but also the “microlens parallax” (which yields the binary mass) and two components of the instantaneous orbital velocity. Thus, we measure, effectively, six “Kepler+1” parameters (two instantaneous positions, two instantaneous velocities, the binary total mass, and the mass ratio). Since Doppler observations of the brighter binary component determine five Kepler parameters (period, velocity amplitude, eccentricity, phase, and position of periapsis), while the same spectroscopy yields the mass of the primary, the combined Doppler + microlensing observations would be verconstrained by 6 + (5 + 1)−(7 + 1) = 4 degrees of freedom. This makes possible an extremely strong test of the microlensing solution.We also introduce a uniform microlensing notation for single and binary lenses, define conventions, summarize all known microlensing degeneracies, and extend a set of parameters to describe full Keplerian motion of the binary lenses.

History

Publication title

The Astrophysical Journal: An International Review of Astronomy and Astronomical Physics

Volume

738

Article number

87

Number

87

Pagination

1-21

ISSN

0004-637X

Department/School

School of Natural Sciences

Publisher

Institute of Physics Publishing Inc

Place of publication

United States

Rights statement

Copyright 2011 American Astronomical Society

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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