2007/03/31 by B. Scott Gaudi, Joseph Patterson, J. Patterson +30 · 1 citation
Physics and Astronomy · #Astrophysics and Star Formation Studies #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/529482
11 pages, 5 figures. Accepted to ApJ, to appear in the May 1, 2008 issue (v678). Minor changes. Data available upon request
arxiv created 2008/03/11 · openalex publication_date 2008/04/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
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.