Eclipsing negative-parity image of gravitational microlensing by a giant-lens star

Abstract

Gravitational Microlensing has been used as a powerful tool for astrophysical studies and exoplanet detections. In the gravitational microlensing, we have two images with negative and positive parities. The negative-parity image is a fainter image and is produced at a closer angular separation with respect to the lens star. In the case of a red-giant lens star and large impact parameter of lensing, this image can be eclipsed by the lens star. The result would be dimming the flux receiving from the combination of the source and the lens stars and the light curve resembles to an eclipsing binary system. In this work, we introduce this phenomenon and propose an observational procedure for detecting this eclipse. The follow-up microlensing telescopes with lucky imaging camera or space-based telescopes can produce high resolution images from the events with reddish sources and confirm the possibility of blending due to the lens star. After conforming a red-giant lens star and source star, we can use the advance photometric methods and detect the relative flux change during the eclipse in the order of $10^{-4}-10^{-3}$. Observation of the eclipse provides the angular size of source star in the unit of Einstein angle and combination of this observation with the parallax observation enable us to calculate the mass of lens star. Finally, we analyzed seven microlensing event and show the feasibility of observation of this effect in future observations.

7 pages, 3 figures

References in corpus (14)

• Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds
• The Effective Temperatures and Physical Properties of Magellanic Cloud Red Supergiants: The Effects of Metallicity
• Spitzer Parallax of OGLE-2015-BLG-0966: A Cold Neptune in the Galactic Disk
• OGLE-III Microlensing Events and the Structure of the Galactic Bulge
• The angular sizes of dwarf stars and subgiants - Non-linear surface brightness relations in BVRcIc from interferometry
• Microlensing as a probe of the Galactic structure; 20 years of microlensing optical depth studies
• OGLE-2011-BLG-0265Lb: a Jovian Microlensing Planet Orbiting an M Dwarf
• Gravitational Microlensing I: A Unique Astrophysical Tool
• OGLE 2004-BLG-254: a K3 III Galactic Bulge Giant spatially resolved by a single microlens
• Study of a Strategy for Parallax Microlensing Detection Towards the Magellanic Clouds
• Red noise versus planetary interpretations in the microlensing event OGLE-2013-BLG-446
• Gravitational Microlensing Events as a Target for SETI project
• The advantages of using a Lucky Imaging camera for observations of microlensing events
• KMT-2015-1b: a Giant Planet Orbiting a Low-mass Dwarf Host Star Discovered by a New High-cadence Microlensing Survey with a Global Telescope Network