Removing the Microlensing Blending-Parallax Degeneracy Using Source Variability

Abstract

Microlensing event MACHO 97-SMC-1 is one of the rare microlensing events for which the source is a variable star, simply because most variable stars are systematically eliminated from microlensing studies. Using observational data for this event, we show that the intrinsic variability of a microlensed star is a powerful tool to constrain the nature of the lens by breaking the degeneracy between the microlens parallax and the blended light. We also present a statistical test for discriminating the location of the lens based on the χ^2 contours of the vector Λ, the inverse of the projected velocity. We find that while SMC self lensing is somewhat favored over halo lensing, neither location can be ruled out with good confidence.

15 text pages + 2 tables + 7 figures. Published in the Astrophysical Journal

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Cited by in corpus (10)

• Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds
• The OGLE View of Microlensing towards the Magellanic Clouds. IV. OGLE-III SMC Data and Final Conclusions on MACHOs
• First Space-Based Microlens Parallax Measurement: Spitzer Observations of OGLE-2005-SMC-001
• Microlensing towards the SMC: a new analysis of OGLE and EROS results
• The OGLE View of Microlensing towards the Magellanic Clouds. II. OGLE-II SMC data
• MOA-2010-BLG-523: "Failed Planet" = RS CVn Star
• Microlensing of radially pulsating stars
• Identifying low-amplitude pulsating stars through microlensing observations
• Non-radially pulsating stars as microlensing sources
• Microlensing towards the LMC revisited by adopting a non-Gaussian velocity distribution for the sources