Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit much light (stars) or large objects that block background light. These objects make up only a minor portion of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light.
OGLE-2005-BLG-390Lb is a super-Earth exoplanet orbiting OGLE-2005-BLG-390L, a star 21,500 ± 3,300 light-years from Earth near the center of the Milky Way, making it one of the most distant planets known. On January 25, 2006, Probing Lensing Anomalies NETwork/Robotic Telescope Network (PLANET/Robonet), Optical Gravitational Lensing Experiment (OGLE), and Microlensing Observations in Astrophysics (MOA) made a joint announcement of the discovery. The planet does not appear to meet conditions presumed necessary to support life.
OGLE-2005-BLG-390L is a star thought to be a spectral type M. This dim magnitude 16 galactic bulge star is located in the Scorpius constellation at a far distance of about 21,500 light years.
The Optical Gravitational Lensing Experiment (OGLE) is a Polish astronomical project based at the University of Warsaw that runs a long-term variability sky survey (1992–present). The main goals are the detection and classification of variable stars, discovery of microlensing events, dwarf novae, and studies of the structure of the Galaxy and the Magellanic Clouds. Since the project began in 1992, it has discovered a multitude of extrasolar planets, together with the first planet discovered using the transit method (OGLE-TR-56b) and gravitational microlensing. The project has been led by professor Andrzej Udalski since its inception.
OGLE-2003-BLG-235L (MOA-2003-BLG-53L) is a star in the constellation of Sagittarius. The first gravitational microlensing event for which a planet orbiting the lens was detected around this star. The event occurred in during July 2003. Two groups observed and independently detected the event: the Optical Gravitational Lensing Experiment (OGLE) and the Microlensing Observations in Astrophysics (MOA), hence, the double designation. It is an orange dwarf star of spectral type K, which is accompanied by a giant planet.
OGLE-2005-BLG-169Lb is an extrasolar planet located approximately 2,700 parsecs away in the constellation of Sagittarius, orbiting the star OGLE-2005-BLG-169L. This planet was discovered by the OGLE project using the gravitational microlensing method. Based on a most likely mass for the host star of 0.49 solar mass (M☉), the planet has a mass of 13 times that of Earth (MEarth). Its mass and estimated temperature are close to those of Uranus. It is speculated that this planet may either be an ice giant like Uranus, or a "naked super-Earth" with a solid icy or rocky surface.
OGLE-2005-BLG-071L is a distant, magnitude 19.5 galactic bulge star located in the constellation Scorpius, approximately 11,000 light years away from the Solar System. The star is probably a red dwarf with a mass 43% of that of the Sun.
OGLE-2006-BLG-109L is a dim magnitude 17 M0V galactic bulge star approximately 4,920 light-years away in the constellation of Scorpius.
RoboNet-1.0 was a prototype global network of UK-built 2-metre robotic telescopes, the largest of their kind in the world, comprising the Liverpool Telescope on La Palma, the Faulkes Telescope North on Maui (Hawaii), and the Faulkes Telescope South in Australia, managed by a consortium of ten UK universities under the lead of Liverpool John Moores University. For the technological aims of integrating a global network to act effectively as a single instrument, and maximizing the scientific return by applying the newest developments in e-Science, RoboNet adopted the intelligent-agent architecture devised and maintained by the eSTAR project.
OGLE-2006-BLG-109Lb is an extrasolar planet approximately 4,920 light-years away in the constellation of Sagittarius. The planet was detected orbiting the star OGLE-2006-BLG-109L in 2008 by a research team using Microlensing.
MOA-2007-BLG-192L is a low-mass red dwarf star or brown dwarf, approximately 3,000 light-years away in the constellation of Sagittarius. It is estimated to have a mass approximately 6% of the Sun's. In 2008, an Earth-sized extrasolar planet was announced to be orbiting this object.
The Microlensing Follow-Up Network is an informal group of observers who monitor high magnification gravitational microlensing events in the Milky Way's Galactic Bulge. Its goal is to detect extrasolar planets via microlensing of the parent star by the planet. μFUN is a follow-up network - they monitor microlensing events identified by survey groups such as OGLE and Microlensing Observations in Astrophysics (MOA).
MOA-2010-BLG-477L is a star whose existence was detected when it caused a microlensing event in August, 2010. The microlensing event also revealed the existence of a planet orbiting the star. At first the star was thought to be about 0.67 times the mass of the Sun, in the main-sequence phase of its stellar evolution. But by the time the star should have been separated enough in the sky from the source star of the microlensing event it was not detected, implying that it is actually a dim white dwarf star.
OGLE-2014-BLG-0124Lb is one of the farthest known planets in the universe. It is approximately 13,000 light years away, located near the center of the galaxy. The planet was discovered using a technique called microlensing. In this case it took 150 days. Two telescopes are used to detect the planet and the time difference between identification by each telescope is used to calculate the distance to the planet. This also contributes to determining the mass of the planet which is about half of Jupiter's. The planet orbits a star with a mass of 0.7 solar masses and is 3.1 AUs from it.
OGLE-2007-BLG-349(AB)b is a circumbinary extrasolar planet about 8,000 light-years away in the constellation of Sagittarius. It is the first circumbinary exoplanet to be discovered using the microlensing method of detecting exoplanets.
OGLE-2016-BLG-1190Lb is an extremely massive exoplanet, with a mass about 13.4 times that of Jupiter (MJ), or is, possibly, a low mass brown dwarf, orbiting the G-dwarf star OGLE-2016-BLG-1190L, located about 22,000 light years from Earth, in the constellation of Sagittarius, in the galactic bulge of the Milky Way.
OGLE-2018-BLG-0799Lb is a sub-Saturn-mass exoplanet discovered by the Optical Gravitational Lensing Experiment (OGLE) collaboration, through a gravitational microlensing event that occurred in May 2018. The discovery was announced in October 2020, and published in August 2022.
OGLE-2018-BLG-1119Lb is a Jupiter-like gas giant exoplanet located 5,760 parsecs away, orbiting its host star at a distance of 4.06 AU and taking two years to complete one orbit. It is 0.91 times the mass of Jupiter. It was discovered in 2022 by gravitational microlensing.
OGLE-2012-BLG-0950Lb is a sub-Saturn (super-Neptune)-type planet 2,600 parsecs (8,500 ly) away with 39 or 35 Earth masses. This type of planet was once thought to be extremely rare because of runaway gas accretion, which would create a gap between 4 and 8 Earth radii or 20 and 80 Earth masses, peaking around 32-64 Earth masses. The planet is 2.6 AU from its star. It is likely near-impossible to know much else about the planet's properties because it was detected by gravitational microlensing. The mass of the host star is approximately 0.56 solar masses. This exoplanet was the first to have its mass found out using only microlens parallax and lens flux.
