Astronomers Discover New Brown Dwarf With Extreme Orbit

An international team of astronomers led by Beth Henderson of the University of Leicester in the UK have announced the discovery of a new brown dwarf, designated TOI-2490 b. The object, which orbits a Sun-like star, has a mass about 74 times that of Jupiter and moves on a highly eccentric orbit.

There are two likely scenarios for why CWISE J1249 — an ultralight star or an underdeveloped brown dwarf star — was able to accelerate to supergalactic speeds. One is that it was paired with a white dwarf that went supernova and used the energy of its explosion to give its partner an extra boost. Another is that CWISE J1249 hailed from a dense globular cluster where it happened to fly through the gravity well of one or two black holes. Scientists aren’t ready to make a definitive statement yet about how CWISE J1249 got to this point, but they promise to continue observing.

This brown dwarf has intrigued astronomers with its orbit. Its eccentricity is 0.78. It is so elongated that TOI-2490 b constantly experiences powerful temperature fluctuations. When the brown dwarf approaches the star during its 60-day orbit, its temperature increases by about 1,000 degrees compared to when it passes the apocenter of its orbit.