Astronomers have discovered a new brown dwarf planet with an unusual orbit

An international team of astronomers led by Beth Henderson from the University of Leicester in the UK has announced the discovery of a new brown dwarf, designated TOI-2490 b. This object, orbiting a Sun-like star, has a mass approximately 74 times that of Jupiter and moves in a highly eccentric orbit.TOI-2490 b is similar in size to Jupiter, with a mass of about 73.6 Jupiter masses, giving it a density of 91.6 g/cm³. The brown dwarf completes an orbit around its parent star every 60.33 days, at a distance of about 0.31 AU. The equilibrium temperature of TOI-2490 b is estimated to be 464.2 K.Observations have shown that the orbital eccentricity of TOI-2490 b is approximately 0.78. This makes TOI-2490 b the most “eccentric” brown dwarf in the so-called BD desert — a region lacking brown dwarfs around main-sequence stars within about 3 AU of the host.Analyzing the collected data, the discovery authors concluded that TOI-2490 b likely formed with such a high level of eccentricity. They added that this brown dwarf probably formed through star formation mechanisms and is expected to have similar metallicity and age as its parent star.The study also showed that the irradiation temperature of TOI-2490 b varies by about 1000 K (from 545 to 1552 K) as it moves along its orbit. However, further observations are needed to fully understand such extreme variation.The host star, TOI-2490, has a mass comparable to the Sun, with a radius measured at about 1.1 solar radii. The star’s age is estimated to be 7.9 billion years, its metallicity is 0.32 dex, and its effective temperature is 5558 K.