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Spectroscopic Characterisation of Microlensing Events: Towards a New Interpretation of OGLE-2011-BLG-0417The microlensing event OGLE-2011-BLG-0417 is an exceptionally bright lens binary that was predicted to present radial velocity variation at the level of several km s1. Pioneer radial velocity follow-up observations with the UVES spectrograph at the ESOVLT of this system clearly ruled out the large radial velocity variation, leaving a discrepancy between the observation and the prediction. In this paper, we further characterise the microlensing system by analysing its spectral energy distribution (SED) derived using the UVES spectrum and new observations with the ARCoIRIS (CTIO) near-infrared spectrograph and the Keck adaptive optics instrumentNIRC2 in the J, H, and Ks-bands. We determine the mass and distance of the stars independently from the microlensing modelling. We find that the SED is compatible with a giant star in the Galactic bulge and a foreground star with a mass of 0.94 +/- 0.09 M solar mass at a distance of 1.07 +/- 0.24 kpc. We find that this foreground star is likely the lens. Its parameters are not compatible with the onespreviously reported in the literature (0.52 +/- 0.04 M solar mass at 0.95 +/- 0.06 kpc), based on the microlensing light curve. A thoughtful reanalysis of the microlensing event is mandatory to fully understand the reason of this new discrepancy. More importantly, this paper demonstrates that spectroscopic follow-up observations of microlensing events are possible and provide independent constraints on the parameters of the lens and source stars, hence breaking some degeneracies in the analysis. UV-to-NIR low-resolution spectrographs like X-shooter (ESOVLT) could substantially contribute to this follow-up efforts, with magnitude limits above all microlensing events detected so far.
Document ID
20170011300
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Santerne, A.
(Universidade do Porto Porto, Portugal)
Beaulieu, J.-P.
(Paris VI Univ. France)
Rojas Ayala, B.
(Universidade do Porto Porto, Portugal)
Boisse, I.
(Aix-Marseille Univ. Marseille, France)
Schlawin, E.
(Arizona Univ. Tucson, AZ, United States)
Almenara, J.-M.
(Grenoble-1 Univ. France)
Batista, V.
(Paris VI Univ. France)
Bennett, D.
(Notre Dame Univ. Notre Dame, IN, United States)
Diaz, R. F.
(Universite de Geneve Switzerland)
Figueira, P.
(Universidade do Porto Porto, Portugal)
James, D. J.
(Cerro Tololo Inter-American Observatory La Serena, Chile)
Herter, T.
(Cornell Univ. Ithaca, NY, United States)
Lillo-Box, J.
(European Southern Observatory Santiago, Chile)
Marquette, J. B.
(Paris VI Univ. France)
Ranc, C.
(Paris VI Univ. France)
Santos, N. C.
(Universidade do Porto Porto, Portugal)
Sousa, S. G.
(Universidade do Porto Porto, Portugal)
Date Acquired
November 28, 2017
Publication Date
November 17, 2016
Publication Information
Publication: Astronomy & Astrophysics
Publisher: EDP Sciences
Volume: 595
Issue: 8
ISSN: 0004-6361
e-ISSN: 1432-0746
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN41548
Funding Number(s)
CONTRACT_GRANT: NNG17PT01A
Distribution Limits
Public
Copyright
Other
Keywords
microlensing event OGLE-2011-BLG-0417

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