Related Research Articles
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. Gravitational microlensing was first theorised by Refstal (1964) and first discovered by Irwin et al (1988). The first object in the sky where it was discovered was the Einstein cross or Huchra lens 2237 +0305. The initial lightcurve of the object was published by Corrigan et al (1991). In Corrigan et al (1991) they calculated that the object causing the microlensing was a Jupiter sized object. This was the first discovery of a planet in another galaxy.
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.
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.
MACHO-1997-BLG-41, commonly abbreviated as 97-BLG-41 or MACHO-97-BLG-41, was a gravitational microlensing event located in Sagittarius which occurred in July 1999. The source star is likely a giant or subgiant star of spectral type K located at a distance of around 8 kiloparsecs. The lens star is a binary system approximately 10,000 light-years away in the constellation Sagittarius. The two stars are separated from each other by about 0.9 AU and have an orbital period of around 1.5 years. The most likely mass of the system is about 0.3 times that of the Sun. Star A and star B are both red dwarfs.
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 (M🜨). 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-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.
MOA-2007-BLG-192Lb, occasionally shortened to MOA-192 b, is an extrasolar planet approximately 3,000 light-years away in the constellation of Sagittarius. The planet was discovered orbiting the brown dwarf or low-mass star MOA-2007-BLG-192L. At a mass of approximately 3.3 times Earth, it is one of the lowest-mass extrasolar planets at the time of discovery. It was found when it caused a gravitational microlensing event on May 24, 2007, which was detected as part of the MOA-II microlensing survey at the Mount John University Observatory in New Zealand.
OGLE-2003-BLG-235Lb/MOA-2003-BLG-53Lb is an extrasolar planet discovered in April 2004 by the OGLE and MOA collaborations. Its high mass indicates that it is most probably a gas giant planet similar to Jupiter. It is located around 4.3 AU away from its parent star.
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.
MOA-2007-BLG-400Lb is an extrasolar planet located approximately 20000 light-years away in the constellation of Sagittarius, orbiting the star MOA-2007-BLG-400L. This planet was detected on September 18, 2008 by the gravitational microlensing by Dong. It has mass between 50% and 130% of Jupiter and orbits between 0.6 and 1.1 AU.
MOA-2008-BLG-310L is a 23rd magnitude star located at least 20000 light years away in the constellation Scorpius. This star has mass 0.67 solar masses which imply that it could probably be a late K-type star.
MOA-2008-BLG-310Lb is an extrasolar planet which orbits probably the late K-type star MOA-2008-BLG-310L, located at least 20000 light years away in the constellation Scorpius. This planet has mass 23% of Jupiter or 77% of Saturn and orbits at 1.25 AU from the star. This planet was discovered by using the gravitational microlensing method on August 4, 2009. As it is typical for exoplanets detected by microlensing method, the orbital period and eccentricity are not determined.
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-2009-BLG-387Lb is an exoplanet in the orbit of the red dwarf MOA-2009-BLG-387L. Its discovery was announced on February 21, 2011, making it the eleventh planet discovered using gravitational microlensing. The planet is thought to be over twice the mass of Jupiter and to have an orbit 80 percent larger than that of Earth's, lasting approximately 1,970 days. However, its exact characteristics are difficult to constrain because the characteristics of the host star are not well known.
MOA-2009-BLG-387L is a red dwarf in the Sagittarius constellation that is host to the planet MOA-2009-BLG-387Lb. The star is estimated to be nearly 20,000 light years away and approximately one fifth the mass of the Sun, although large confidence intervals exist, reflecting the uncertainties in both the mass and distance. The star drew the attention of astronomers when it became the lens of gravitational microlensing event MOA-2009-BLG-387L, in which it eclipsed a background star and created distorted caustics, an envelope of reflected or refracted light rays. Analysis of the caustic events and of follow-up observational data led to the planet's discovery, which was reported in February 2011.
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-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.
References
- Dong, Subo; et al. (2009). "Microlensing Event MOA-2007-BLG-400: Exhuming the Buried Signature of a Cool, Jovian-Mass Planet" (abstract). The Astrophysical Journal . 698 (2): 1826–1837. arXiv: 0809.2997 . Bibcode:2009ApJ...698.1826D. doi:10.1088/0004-637X/698/2/1826. S2CID 16658501. web preprint
