The white dwarf named ZTF J1901 + 1458 and located about 130 light years distant from Earth, is slightly larger than the Moon; the smallest known star of its kind. A white dwarf is the remnant that remains when certain stars are turned off. This one, in particular , is only 4,280 kilometers in diameter but a mass about 1.35 times the mass of the Sun. Most white dwarfs are closer to the size of Earth, which has a radius of about 6,300 kilometers.
The fact that it is so small makes it one of the most massive known objects of its kind. His turn is also spectacular. The white dwarf spins about once every seven minutes. And it has a powerful magnetic field, more than a billion times the strength of Earth.
Its density and mass place it right on the edge of the Chandrasekhar limit, the maximum mass a white dwarf can have before becoming so unstable that it explodes in a spectacular supernova.
Scientists used the Zwicky Transitional Facility at the Palomar Observatory in California , which searches for objects in the sky that change brightness to find this particular cosmic object.
According to the researchers’ analysis, the white dwarf is the product of a fusion between two smaller white dwarfs resulting in a single, extra-large mass, ultra-small white dwarf . It is only about 100 million years old, with a fairly exorbitant magnetic field for a white dwarf; as we have seen, a billion times more powerful than the Sun. If it were more massive, it could not support its own weight and would explode.
Referencia: I. Caiazzo et al. A highly magnetized and rapidly rotating white dwarf as small as the Moon. Nature. Published online June 30, 2021. doi: 10.1038/s41586-021-03615-y.
