2023-11-30 23:52:00
A huge exoplanet (LHS 3154b) was discovered orbiting very close to the red dwarf ‘LHS 3154’, which is 50 light-years away from Earth. This planet, which is 13 times the size of Earth, is considered to be too large for its central star, which is only one-ninth the size of the Sun, and thus runs counter to existing theories of planet formation. On the 1st, an international research team led by Dr. Gudmundur Stefansson of the Department of Astrophysics at Princeton University announced in the scientific journal Science that they had discovered a massive exoplanet in close orbit around LHS 3154 using the near-infrared spectrometer at the McDonald Observatory in Texas. Planets form in dense nebular disks of gas and dust surrounding newborn stars, and their size is determined by the amount of material contained in the disk. ▲ Image of the exoplanet LHS 3154b (front) and the red dwarf HHS 3154, one-ninth the size of the Sun. LHS 3154b, an exoplanet that orbits LHS 3154, a red dwarf only one-ninth the size of the Sun, very close to it with a cycle of 3.7 days, is estimated to have a mass 13 times that of Earth and has a similar composition to Neptune. Planet formation theory holds that the mass of gas and dust in a protoplanetary disk is closely proportional to the mass of the central star, so an exoplanet larger than Neptune (17 times the mass of Earth) would be present in the close orbit of the smallest red dwarf (M-type dwarf). I believe it cannot exist. In this study, the research team closely observed LHS 3154, an M-type dwarf, using the Habitable Zone Planet Detector (HPF), a near-infrared spectrometer mounted on the 10-meter-diameter Haber-Avery Telescope (HET) at McDonald Observatory in Texas. M-type dwarfs are very small stars among red dwarfs, with a mass of less than 25% of the sun, and are the most common stars in our galaxy. These red dwarfs, also called ultra-low-mass dwarfs, are faint and emit most of their radiation in infrared wavelengths, making it difficult to detect nearby exoplanets. For this reason, very few exoplanets orbiting the M type are discovered, and most of the exoplanets that are discovered have a mass much smaller than that of Neptune and their orbits are far away. As a result of observations, LHS 3154, located 51.34 light years away from Earth, has a mass of 11.2% of the Sun and a diameter of 14% of the Sun, making it only one-ninth the size of the Sun, and its effective temperature (Teff) is very low at 2,588°C. It was found that LHS 3154b, which orbits this star, was analyzed as a Neptune-star planet with a minimum mass of 13.15 times that of Earth, and was found to revolve once every 3.71 days in an elliptical orbit (eccentricity 0.076) very close to the central star. The research team said that the fact that a planet with a mass more than 13 times that of Earth orbits a central star one-ninth the size of the Sun in a very close orbit shows that small stars can harbor larger planets than previously thought. He said it challenges existing theoretical models of planet formation. As a result of a planet formation simulation, it was analyzed that for a planet of such a large mass to exist in the close orbit of LHS 3154, the amount of gas and dust in the protoplanetary disk where the planet is formed must be more than 10 times greater than what is generally observed. “HPF has already provided important information in the discovery and identification of new planets, but the discovery of LHS 3154b exceeds all expectations,” said Dr. Stefansson. “HPF has discovered an unknown exoplanet around the lowest-mass star. “This discovery is very special because it was designed, developed and built to investigate,” he said. “We did not expect such a massive exoplanet to exist around a low-mass star,” said co-researcher Subras Mahadevan, a professor at Penn State. “This discovery highlights how little we know about the universe.” “he said. ◆ Source: Science, Guðmundur Stefánsson et al., ‘A Neptune-mass exoplanet in close orbit around a very low-mass star challenges formation models’, www.science.org/doi/10.1126/science.abo0233 Science Team press@jeonpa .co.kr<저작권자 © 전파신문, 무단 전재 및 재배포 금지>
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