Discovery of a Very Bright, Nearby Gravitational Microlensing Event

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https://iopscience.iop.org/article/10.1086/529482

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https://doi.org/10.1086/529482
 http://hdl.handle.net/11603/19595

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UMBC Physics Department
UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
UMBC Joint Center for Earth Systems Technology (JCET)

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2008-01-10

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journal articles preprints
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Citation of Original Publication

B. Scott Gaudi et al, Discovery of a Very Bright, Nearby Gravitational Microlensing Event, ApJ 677 1268 (2008), https://doi.org/10.1086/529482

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© 2008. The American Astronomical Society. All rights reserved

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Abstract

We report the serendipitous detection of a very bright, very nearby microlensing event. In late 2006 October, an otherwise unremarkable A0 star at a distance of ~1 kpc (GSC 3656–1328) brightened achromatically by a factor of nearly 40 over the span of several days and then decayed in an apparently symmetrical way. We present a light curve of the event based on optical photometry from the Center for Backyard Astrophysics and the All Sky Automated Survey, as well as near-infrared photometry from the Peters Automated Infrared Imaging Telescope. This light curve is well fit by a generic microlensing model. We also report optical spectra and Swift X-ray and UV observations that are consistent with the microlensing interpretation. We discuss and reject alternative explanations for this variability. The lens star is probably a low-mass star or brown dwarf, with a relatively high proper motion of >= 20 mas yr⁻¹, and may be visible using precise optical/infrared imaging taken several years from now. A modest, all-sky survey telescope could detect ~10 such events per year, which would enable searches for very low mass planetary companions to relatively nearby stars.