Over 5,000 exoplanets have been detected to date, with more than 90% of them found by using the transit or radial velocity techniques. Of the other 10%, 105 were found using the microlensing method which takes advantage of the fact that the path of a light beam is bent by the presence of a massive body. The gravitational force of the body acts like a lens (a “gravitational lens”) to distort the image of an object seen behind it. When a massive object fortuitously passes in front of a star, it acts as a gravitational lens and thus its motion across the sky causes the background star to appear to brighten briefly. When the foreground object is a star hosting a planet, both bodies can produce brightening events as they pass in front of the star, and the flashes as seen from Earth can be modeled to determine their masses and separation.
Two significant advantages are offered by the microlensing method over more common exoplanet detection techniques. First, the brightness of the microlensing effect does not depend on the brightness of the moving body, only on its mass, which makes it possible to spot faint, low-mass M dwarf stars. The second advantage is that the microlensing planet may orbit its star at a large distance, even many astronomical units. (Since normal
Harvard-Smithsonian Center for Astrophysics (
Reference: “OGLE-2017-BLG-1049: Another Giant Planet Microlensing Event” Yun Hak Kim, Sun-Ju Chung, A. Udalski, Ian A. Bond, Youn Kil Jung, Andrew Gould, Michael D. Albrow, Cheongho Han, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Hyoun-Woo Kim, Seung-Lee Kim, Chung-Uk Lee and Dong-Joo Lee, 31 December 2020, Journal of the Korean Astronomical Society.
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