http://arxiv.org/abs/1807.11077
Context. Astrometric gravitational microlensing is an excellent tool to determine the mass of stellar objects. Using precise astrometric measurements of the lensed position of a background source in combination with accurate predictions of the positions of lens and unlensed source it is possible to determine the mass of the lens with an accuracy of a few percent. Aims. Making use of the recently published Gaia DR2 catalogue we want to predict astrometric microlensing events by foreground stars with high proper motion passing a background source in the next decades. Methods .We select roughly 148 000 high-proper-motion stars from Gaia DR2 with mu_tot >150mas/yr as potential lenses. We then search for background sources close to their paths. Using the astrometric parameters of Gaia DR2 we calculate the future positions of source and lens. With a nested-intervals algorithm we determine the date and separation of the closest approach. Using Gaia DR2 photometry we determine an approximate mass of the lens, which we use to calculate the expected microlensing effects. Results. We predict 3914 microlensing events by 2875 different lenses between 2010 and 2065 with expected shifts larger than 0.1 mas between the lensed and unlensed positions of the source. 513 of those are expected to happen between 2014.5 – 2026.5 and might be measured by Gaia. For 127 events we also expect a magnification between 1 mmag and 3 mag.
J. Klüter, U. Bastian, M. Demleitner, et. al.
Tue, 31 Jul 18
31/69
Comments: 11 Pages, 14 figures, 2 tables, Submitted to A&A
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