Суперземля OGLE 2005 BLG 390Lb: Открытие в центре Млечного Пути

Super Earth orbiting OGLE 2005 BLG 390L
OGLE 2005 BLG 390Lb (known sometimes as Hoth by NASA) is a super Earth exoplanet orbiting OGLE 2005 BLG 390L, a star 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 planet is estimated to be about five times Earth's mass (5.5 ). Some astronomers have speculated that it may have a rocky core like Earth, with a thin atmosphere. Its distance from the star, and the star's relatively low temperature, means that the planet's likely surface temperature is around , making it one of the coldest known. If it is a rocky world, this temperature would make it likely that the surface would be made of frozen volatiles, substances which would be liquids or gases on Earth: water, ammonia, methane and nitrogen would all be frozen solid. If it is not a rocky planet, it would more closely resemble an icy gas planet like Uranus, although much smaller. assistant director for the mathematical and physical sciences directorate at the National Science Foundation, which supported the work. At the time of discovery, with 5.5 Earth masses, the planet was less massive than the previous candidate for lowest mass exoplanet around a main sequence star, the 7.5 Earth mass Gliese 876 d. Since 2013, many Earth sized or smaller planets around main sequence stars have been detected by the Kepler spacecraft and others.

OGLE 2005 BLG 390L (located in the constellation Scorpius, RA 17:54:19.2, Dec −30°2238, J2000, 6.6 ± 1.0 kpc distance) is thought to likely be a cool red dwarf (95% probability), or a white dwarf (4% probability), with a very slight chance that it is a neutron star or black hole (<1% probability). Regardless of the star's classification, its radiant energy output would be significantly less than that of the Sun. It has a mass of 0.22 , but an unknown radius. If it is a red dwarf, it would likely have a radius of 0.17 The age is estimated to be around 9.587 billion years old.

OGLE 2005 BLG 390Lb orbits its star every 3,500 days (about 10 years) at an average distance of , or an orbit that would fall between the orbits of Mars and Jupiter in the Solar System (This range of distances is the range of error in measurement and calculation; it does not represent the planet's orbital eccentricity, as its orbital elements are not known, other than its orbital period). Until this discovery, no small exoplanet had been found farther than from a main sequence star. The planet takes approximately 10 Earth years to orbit its star, OGLE 2005 BLG 390L. Gravitational lensing occurs when light from a distant star is bent and magnified by the gravitational field of a foreground star. A gravitational microlensing event occurs when a planet accompanying this foreground star can cause an additional small increase in the intensity of magnified light as it passes between the background star and the observer as well. The PLANET/RoboNet campaign regularly investigates promising microlensing event alerts that are issued by the Polish OGLE or the Japanese–New Zealand MOA survey. The observation of just such an event led to the discovery of OGLE 2005 BLG 390Lb. OGLE detected the microlensing effect produced by the star OGLE 2005 BLG 390L, and it was the PLANET team's follow up observations and analysis which uncovered evidence of the planet itself.