The properties of the object, which has much less iron and other metals than other stars and brown dwarfs, suggest it is quite old, “probably from one of the earliest generations of stars in our galaxy.”

NASA pointed to two theories for why the object moved at such a high speed. One is that it originally came from a binary system with a white dwarf (the stellar core left behind after a dying star uses up its nuclear fuel), which exploded as a supernova when it ripped away too much material from its companion.