Microlensing by Stars

Abstract

If stars at the lower end of the main sequence are responsible for the microlensing events observed in the Galactic bulge, then light from the lensing star contributes to the observed brightness. The background and lensing stars generally have different colors, and the relative brightness changes during the microlensing event. Therefore, microlensing light curves are not perfectly achromatic if hydrogen-burning stars are the lenses. In most cases, the color shift will be too small to be observable, but we argue that given the current microlensing rates, it is plausible that a few color-shifted microlensing events could be observed in the near future, especially if strategies are optimized to search for them. Although rare, such an event could potentially provide a wealth of information: Light curves in two bands can be used to determine the masses and distances of the two stars as well as the transverse speed of the lensing star. Light curves in additional wavebands could make the determination more precise.

11 pages, uuencoded, compressed Postscript

Cited by in corpus (20)

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• Systematic Analysis of 22 Microlensing Parallax Candidates
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• Blending in Gravitational Microlensing Experiments: Source Confusion And Related Systematics
• REMOVING DEGENERACY OF MICROLENSING LIGHT CURVES THROUGH NARROW-BAND PHOTOMETRY OF GIANTS
• A New Channel for the Detection of Planetary Systems Through Microlensing: II. Repeating Events
• Identifying Microlensing by Binaries
• On the Feasibility of Characterizing Lens Stars in Future Space-Based Microlensing Surveys
• Parallax-Shifted Microlensing Events from Ground-Based Observations of the Galactic Bulge
• On the Nature and Location of the Microlenses
• Analytic Relations between the Observed Gravitational Microlensing Parameters With and Without the Effect of Blending
• An Additional Application of the Space Interferometry Mission to Gravitational Microlensing Experiments
• Towards Locating the Brightest Microlensing Events on the Sky
• Bright Lenses and Optical Depth
• Observational Evidence for the Effect of Amplification Bias in Gravitational Microlensing Experiments
• Colour Change Measurements of Gravitational Microlensing Events by Using the Difference Image Analysis Method
• Color-Shift Measurement in Microlensing-Induced Stellar Variation from Future Space-Based Surveys