When they do, if their combined mass exceeds the Chandrasekhar limit, you’ll get a stellar cataclysm: a type Ia supernova, which can briefly shine as bright as some ~10 billion Suns.īut if their combined mass remains below that critical threshold instead - and keep in mind that some white dwarfs can be incredibly low in mass, with the lowest-mass one coming in at just ~17% the mass of the Sun - they’ll simply lead to the formation of another white dwarf. Just as binary black holes and neutron stars are known to inspiral and merge, so, too, will white dwarfs in binary systems.
The brightest star in our night sky, Sirius, has a white dwarf and a star more massive than the Sun orbiting one another come back in about a billion years, and you’re almost certain to find two white dwarfs orbiting one another instead.īut that’s the beginning of the story, not the end. If one star in a binary system becomes a white dwarf, the other one likely won’t be far behind. The reason this matters is that many binary systems are born with stars of similar masses, and hence they have similar fates. Additionally, about half of all the stars we know of are part of a system with two or more stars in them singlet systems like our own are extremely common, but binaries, trinaries, and other multi-star configurations are quite common as well. 95% of the stars in our galaxy are less massive than our Sun, but that remaining 5% means that approximately 20 billion stars in the Milky Way are more massive than we are. While we might look at our Solar System and our Sun as a “typical” example of what’s out there, it’s important to recognize that we’re only a sample size of 1, and that nature comes in all sorts of varieties.