First Space-based Microlens Parallax Measurement of an Isolated Star: Spitzer Observations of OGLE-2014-BLG-0939
We present the first space-based microlens parallax measurement of an isolated star. From the striking differences in the lightcurve as seen from Earth and from Spitzer (~ 1 AU to the west), we infer a projected velocity v_(hel) ~ 250kms^(-1), which strongly favors a lens in the Galactic Disk with mass M = 0.23 ± 0.07 M_☉ and distance D_L =3.1 ± 0.4 kpc. An ensemble of such measurements drawn from our ongoing program could be used to measure the single-lens mass function including dark objects, and also is necessary for measuring the Galactic distribution of planets since the ensemble reflects the underlying Galactic distribution of microlenses. We study the application of the many ideas to break the four-fold degeneracy first predicted by Refsdal 50 years ago. We find that this degeneracy is clearly broken, but by two unanticipated mechanisms: a weak constraint on the orbital parallax from the ground-based data and a definitive measurement of the source proper motion.
© 2015 American Astronomical Society. Received 2014 October 21; accepted 2015 January 20; published 2015 March 24. Work by JCY, AG, and SC was supported by JPL grant 1500811. Work by JCY was performed under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. 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 to AU. AG and BSG were supported by NSF grant AST 1103471. AG, BSG, and RWP were supported by NASA grant NNX12AB99G. RP was supported by the Polish Ministry of Science and Higher Education program Iuventus Plus award No. IP2011 043571. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.
Published - 0004-637X_802_2_76.pdf
Submitted - 1410.5429v3.pdf