OGLE-2017-BLG-1186: First application of asteroseismology and Gaussian processes to microlensing

S. S. Li*, W. Zang, A. Udalski, Y. Shvartzvald, D. Huber, C. U. Lee, T. Sumi, A. Gould, S. Mao, P. Fouqué, T. Wang, S. Dong, U. G. Jørgensen, A. Cole, P. Mróz, M. K. Szymanski, J. Skowron, R. Poleski, I. Soszynski, P. PietrukowiczS. Kozłowski, K. Ulaczyk, K. A. Rybicki, P. Iwanek, J. C. Yee, S. Calchi Novati, C. A. Beichman, G. Bryden, S. Carey, B. S. Gaudi, C. B. Henderson, W. Zhu, M. D. Albrow, S. J. Chung, C. Han, K. H. Hwang, Y. K. Jung, Y. H. Ryu, I. G. Shin, S. M. Cha, D. J. Kim, H. W. Kim, S. L. Kim, D. J. Lee, Y. Lee, B. G. Park, R. W. Pogge, I. A. Bond, F. Abe, R. Barry, D. P. Bennett, A. Bhattacharya, M. Donachie, A. Fukui, Y. Hirao, Y. Itow, I. Kondo, N. Koshimoto, M. C.A. Li, Y. Matsubara, Y. Muraki, S. Miyazaki, M. Nagakane, C. Ranc, N. J. Rattenbury, H. Suematsu, D. J. Sullivan, D. Suzuki, P. J. Tristram, A. Yonehara, G. Christie, J. Drummond, J. Green, S. Hennerley, T. Natusch, I. Porritt, E. Bachelet, D. Maoz, R. A. Street, Y. Tsapras, V. Bozza, M. Dominik, M. Hundertmark, N. Peixinho, S. Sajadian, M. J. Burgdorf, D. F. Evans, R. Figuera Jaimes, Y. I. Fujii, L. K. Haikala, C. Helling, T. Henning, T. C. Hinse, L. Mancini, P. Longa-Peña, S. Rahvar, M. Rabus, J. Skottfelt, C. Snodgrass, J. Southworth, E. Unda-Sanzana, C. von Essen, J. P. Beaulieu, J. Blackman, K. Hill

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing campaign. This is a remarkable microlensing event because its source is photometrically bright and variable, which makes it possible to perform an asteroseismic analysis using ground-based data. We find that the source star is an oscillating red giant with average timescale of ∼9 d. The asteroseismic analysis also provides us source properties including the source angular size (∼27 μas) and distance (∼11.5 kpc), which are essential for inferring the properties of the lens. When fitting the light curve, we test the feasibility of Gaussian processes (GPs) in handling the correlated noise caused by the variable source. We find that the parameters from the GP model are generally more loosely constrained than those from the traditional χ2 minimization method. We note that this event is the first microlensing system for which asteroseismology and GPs have been used to account for the variable source. With both finite-source effect and microlens parallax measured, we find that the lens is likely a ∼0.045 M brown dwarf at distance ∼9.0 kpc, or a ∼0.073 M ultracool dwarf at distance ∼9.8 kpc. Combining the estimated lens properties with a Bayesian analysis using a Galactic model, we find a ∼ 35 per cent probability for the lens to be a bulge object and ∼ 65 per cent to be a background disc object.

Original languageEnglish
Pages (from-to)3308-3323
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume488
Issue number3
DOIs
StatePublished - 21 Sep 2019

Funding

FundersFunder number
ANR-18-CE31-0002
Italian Minister of Instruction, University and Research
Universities Space Research Association
National Science FoundationJP17H02871, JSPS24253004, JSPS15H00781, AST-1516842, JSPS23340064, AST-1717000, JSPS26247023, JP16H06287
National Science Foundation
National Aeronautics and Space Administration
Jet Propulsion Laboratory2017R1A4A1015178, 11573003, 1500811
Jet Propulsion Laboratory
Australian Research CouncilLE110100055
Australian Research Council
University of Tasmania
Deutsche ForschungsgemeinschaftWA 1047/11-1
Deutsche Forschungsgemeinschaft
Agence Nationale de la Recherche
National Natural Science Foundation of China11761131004, 11821303
National Natural Science Foundation of China
Fundação para a Ciência e a TecnologiaUID/Multi/00611/2013
Fundação para a Ciência e a Tecnologia
Centre National d’Etudes Spatiales
Ministero dell’Istruzione, dell’Università e della Ricerca
National Research Foundation of Korea
Narodowe Centrum NaukiMAESTRO 2014/14/A/ST9/00121
Narodowe Centrum Nauki
European Regional Development FundPOCI-01-0145-FEDER-006922
European Regional Development Fund

    Keywords

    • Asteroseismology
    • Gravitational lensing: micro
    • Stars: fundamental parameters
    • Stars: oscillations

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