Two White Dwarfs Merged Together Into a Single "Ultramassive" White Dwarf

Astronomers have found a white dwarf that was once two white dwarfs. The pair of stars merged into one about 1.3 billion years ago. The resulting star, named WDJ0551+4135, is about 150 light years away. A white dwarf is the end state of stars like our Sun. Once they’ve consumed their nuclear fuel, they expel …