Journal Article

Repeating microlensing events in the OGLE data

J. Skowron, Ł. Wyrzykowski, S. Mao and M. Jaroszyński

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 393, issue 3, pages 999-1009
Published in print March 2009 | ISSN: 0035-8711
Published online February 2009 | e-ISSN: 1365-2966 | DOI:
Repeating microlensing events in the OGLE data

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Microlensing events are usually selected among single-peaked non-repeating light curves in order to avoid confusion with variable stars. However, a microlensing event may exhibit a second microlensing brightening episode when the source or/and the lens is a binary system. A careful analysis of these repeating events provides an independent way to study the statistics of wide binary stars and to detect extrasolar planets. Previous theoretical studies predicted that 0.5–2 per cent of events should repeat due to wide binary lenses. We present a systematic search for such events in about 4000 light curves of microlensing candidates detected by the Optical Gravitational Lensing Experiment (OGLE) towards the Galactic bulge from 1992 to 2007. The search reveals a total of 19 repeating candidates, with six clearly due to a wide binary lens. As a by-product, we find that 64 events (∼2 per cent of the total OGLE-III sample) have been misclassified as microlensing; these misclassified events are mostly nova or other types of eruptive stars. The number and importance of repeating events will increase considerably when the next-generation wide-field microlensing experiments become fully operational in the future.

Keywords: gravitational lensing; stars: planetary systems; binaries: general; Galaxy: bulge

Journal Article.  6348 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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