Not Quite a Star, Not Quite a Planet, but Hotter Than the Sun

Israeli researchers have stumbled on a celestial object that "is seriously confronting our notions of what's possible in the universe." That's per Science Alert, which reports on the discovery of a sweltering brown dwarf—an object that falls somewhere between planet and star, but which boasts temperatures even hotter than our own sun. A team from the Weizmann Institute of Science first spotted WD 0032–317B, said to be more than 1,400 light-years from Earth, in 2019, then again in 2020 using the European Southern Observatory's Very Large Telescope.

The brown dwarf was seen orbiting its own host star, a white dwarf, and astronomers think that at one point about a million years ago, the two objects were caught up together in a gas envelope, per Gizmodo. Whatever the origin story, what scientists know now about WD 0032-317B is that it's hot—really hot. As in nearly 14,000 degrees Fahrenheit, a bit steamier than the sun's 9,900 degrees. Science Alert notes it's "the hottest object of its kind" ever found.

Brown dwarfs are larger than even big planets like Jupiter—this one is said to be about 75 to 90 times the mass of our solar system's largest planet—but they're typically smaller than stars and don't have the same hefty mass to burn hydrogen for nuclear fusion, leading to the rather sad nickname of "failed stars." Gizmodo notes, in the research published Monday in the Nature Astronomy journal, that the scientists give this new brown dwarf the nicer label of "irradiated-Jupiter analogue."

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The team says that their find could help lend more insight into what happens to huge, Jupiter-like gas giants that are orbiting around larger burning stars. Typically, planets that do so see their atmospheres evaporate from the huge amounts of ultraviolet light shone in their direction from the host star. That, in turn, leads to molecules breaking apart, a process known as thermal dissociation. If even more brown dwarfs are eventually found, it could help "clarify the diversity and nature of these hot, massive objects," per Gizmodo. (More discoveries stories.)