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A rogue planet is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf. Rogue planets may originate from planetary systems in which they are formed and later ejected, or they can also form on their own, outside a planetary system. The Milky Way alone may have billions to trillions of rogue planets, a range the upcoming Nancy Grace Roman Space Telescope will likely be able to narrow down.
OGLE-TR-111 is a yellow dwarf star approximately 5,000 light-years away in the constellation of Carina. Having an apparent magnitude of about 17, this distant and dim star has not yet been cataloged. Because its apparent brightness changes when one of its planets transits, the star has been given the variable star designation V759 Carinae.
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.
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 (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-2005-BLG-071Lb is a planet discovered by the Optical Gravitational Lensing Experiment (OGLE) and others in 2005, using gravitational microlensing. According to the best fit model, it has about 3.5 times the mass of Jupiter and a projected separation of 3.6 astronomical units from the star. This would result in an effective temperature around 50 K, similar to that of Neptune. However, an alternative model which gives a slightly lower mass of 3.3 times that of Jupiter and a projected separation of 2.1 AU is only slightly less likely. It may be the most massive planet currently known around a red dwarf 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-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.
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-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-1195Lb is an extrasolar planet located about 22,000 light-years from Earth, in the galactic bulge, orbiting the 0.57±0.06M☉ star OGLE-2016-BLG-1195L, discovered in 2017. The planet was detected using gravitational microlensing techniques managed by the Korea Astronomy and Space Science Institute and the Spitzer Space Telescope. Initially, it was believed the planet has a mass similar to Earth and is located about the same distance from its host star as the Earth is from the Sun, although it was expected to be much colder.
OGLE-2011-BLG-0462, also known as MOA-2011-BLG-191, is a stellar-mass black hole isolated in interstellar space. OGLE-2011-BLG-0462 lies at a distance of 5,000 light years in the direction of the galactic bulge in the constellation Sagittarius. The black hole has a mass between 1.6 and 4.4 M☉, but might weigh as much as 7.1±1.3 M☉ The discovery of OGLE-2011-BLG-0462 makes this object the first truly isolated black hole found. OGLE-2011-BLG-0462 was discovered through microlensing when it passed in front of a background star that was 20,000 light years away from Earth. The black hole's gravity bent the star's light, causing a sharp spike in brightness that was detected by the Hubble Space Telescope. It took six years to confirm the existence of OGLE-2011-BLG-0462. Its initial kick velocity has been estimated to have an upper limit of 100 km/s.
References
- 1 2 3 4 Dong, Subo; et al. (2009). "OGLE-2005-BLG-071Lb, the Most Massive M Dwarf Planetary Companion?". The Astrophysical Journal. 695 (2): 970–987. arXiv: 0804.1354 . Bibcode:2009ApJ...695..970D. doi:10.1088/0004-637X/695/2/970. S2CID 119186629.
- 1 2 3 4 Bennett, David P.; Bhattacharya, Aparna; Beaulieu, Jean-Philippe; Blackman, Joshua W.; Vandorou, Aikaterini; Terry, Sean K.; Cole, Andrew A.; Henderson, Calen B.; Koshimoto, Naoki; Lu, Jessica R.; Baptiste Marquette, Jean; Ranc, Clément; Udalski, Andrzej (2020). "Keck Observations Confirm a Super-Jupiter Planet Orbiting M Dwarf OGLE-2005-BLG-071L". The Astronomical Journal. 159 (2): 68. arXiv: 1909.04740 . Bibcode:2020AJ....159...68B. doi: 10.3847/1538-3881/ab6212 . S2CID 202558435.
- ↑ Udalski, A.; et al. (2005). "A Jovian-Mass Planet in Microlensing Event OGLE-2005-BLG-071". The Astrophysical Journal. 628 (2): L109–L112. arXiv: astro-ph/0505451 . Bibcode:2005ApJ...628L.109U. doi:10.1086/432795. S2CID 7425167.
