Only a smidge bigger than the moon, a newfound white dwarf star is that the smallest of its kind known.
The white dwarf star, a kind of remnant left behind when certain stars peter out, features a radius of about 2,100 kilometers, researchers report June 30 in Nature. That’s remarkably on the brink of the moon’s approximately 1,700-kilometer radius. Most white dwarfs are closer to the dimensions of Earth, which features a radius of about 6,300 kilometers.
The white dwarf’s small girth means, counterintuitively, that it’s also one among the foremost massive known objects of its kind, at about 1.3 times the sun’s mass. That’s because white dwarfs shrink as they gain mass.
“That’s not the sole very amazing characteristic of this white dwarf star,” astrophysicist Ilaria Caiazzo of Caltech said on June 28 in a web press conference. “It is additionally rapidly rotating.”
The white dwarf star spins around approximately once every seven minutes. And it’s a strong magnetic flux, quite a billion times the strength of Earth’s. Caiazzo and colleagues discovered the weird stellar remnant, dubbed ZTF J1901+1458, and located about 130 light-years from Earth, using the Zwicky Transient Facility at Palomar Observatory in California, which searches for objects within the sky that change in brightness.
The white dwarf star probably formed when two white dwarfs orbited each other and merged to make one white dwarf with an extra-large mass and extra-small size, the team says. That convergence would even have spun up the white dwarf star and given it a robust magnetic flux.
This white dwarf star lives on the edge: If it were far more massive, it wouldn’t be ready to support its own weight, causing it to explode. Studying such objects can help scientists understand the bounds of what’s possible for these dead stars.
