This illustration shows the rapidly rotating, highly magnetized white dwarf with the smallest radius ever found, with Earth’s moon shown nearby for a size comparison. With a radius of ~2,140 km, just about 20% larger than the Moon’s radius, this marks the smallest and most massive white dwarf whose parameters were ever measured this accurately. (GIUSEPPE PARISI)

What The Heaviest, Smallest White Dwarf Ever Found Means For Science

The new record-holder opens up a literal Universe full of possibilities.

Someday, even our own Sun will eventually run out of hydrogen fuel in its core, bringing a tremendous set of changes to our Solar System. Its core will contract and heat up while its outer layers expand and slowly get expelled, signifying our transition into a red giant. When the helium in the core is exhausted, the core will contract further, becoming a carbon/oxygen white dwarf, while the remainder of our star gets blown back into interstellar space in a spectacular planetary nebula. For practically every star born with 40% to 800% of our Sun’s mass, the same fate awaits them all.

The white dwarf that we’re left with is always much less massive than the star it originated from, and never more massive than about 1.4 solar masses. Above this mass limit — known as the Chandrasekhar mass — a spontaneous thermonuclear reaction will occur: a type Ia supernova, destroying the white dwarf entirely. Driven by a series of curious observations, a team of scientists just discovered the most massive white dwarf ever robustly measured: between 1.327 and 1.365 solar masses, and it’s only 2,140 kilometers in radius, or barely larger than the Moon. It’s a fascinating find, but what it teaches us is…