2003/11/05 by A. Riffeser, Arno Riffeser, Jrgen Fliri +7 · 2 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/381019
published as Astrophys.J. 599 (2003) L17-L20 · Accepted for publication in ApJ Letters (28 Oct 2003), 4 pages, 2 color figures, uses emulateapj style
arxiv created 2003/11/05 · openalex publication_date 2003/11/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We report the detection of the first two microlensing candidates from the Wendelstein Calar Alto Pixellensing Project (WeCAPP). Both are detected with a high signal-to-noise ratio and were filtered out from 4.5 million pixel light curves using a variety of selection criteria. Here we only consider well-sampled events with timescales of 1 day < t fwhm < 20 days, high amplitudes, and a low χ 2 of the microlensing fit. The two-color photometry ( R , I ) shows that the events are achromatic and that giant stars with colors of ( R - I ) ≈ 1.1 mag in the bulge of M31 have been lensed. The magnification factors are 64 and 10, which are obtained for typical giant luminosities of M I = -2.5 mag. Both lensing events lasted for only a few days ( t = 1.7 days and t = 5.4 days). The event GL1 is likely identical with PA-00-S3 reported by the POINT-AGAPE project. Our calculations favor in both cases the possibility that MACHOs in the halo of M31 caused the lensing events. The most probable masses, 0.08 M ☉ for GL1 and 0.02 M ☉ for GL2, are in the range of the brown dwarf limit of hydrogen burning. Solar mass objects are a factor of 2 less likely.