Astronomers measure the rotation of a white dwarf ejected by a supernova explosion

Astronomers measure the rotation of a white dwarf ejected by a supernova explosion
Astronomers measure the rotation of a white dwarf ejected by a supernova explosion
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The white dwarf LP 40-365 survived a supernova explosion and was thrown away: now it rushes away from the Galaxy at high speed and at the same time slowly rotates.

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Ursa Minor, about 2,000 light years away, is home to the white dwarf LP 40-365. It is an extremely unusual star, practically devoid of conventional hydrogen and helium and consisting of heavier elements. In addition, it moves at high speed and, apparently, sooner or later will leave the limits of our Galaxy. And recently, astronomers have discovered that LP 40-365 rotates rapidly - this has allowed a better understanding of the background of the strange star. They write about this in an article published in The Astrophysical Journal Letters.

The fast-flying white dwarf LP 40-365 is believed to be a type Iax supernova product. Such explosions begin in a binary star system, one of the participants in which is a dense white dwarf. Gradually, it pulls the substance of its neighbor and, having accumulated too much mass, explodes. In supernovae Iax, the explosion does not cover the entire volume of the white dwarf, and its remnants are thrown away at high speed.

After analyzing the observations of LP 40-365 by the Hubble and TESS space telescopes, JJ Hermes and his colleagues noticed regular fluctuations in brightness. This showed that the speed star also rotates, making a complete revolution in just 8, 9 hours.

In comparison with ordinary stars, this seems to be extremely fast: we recall that the Sun rotates around its axis in 27 of our days. However, for a white dwarf ejected by a supernova, this rotation rate is very low. Therefore, astronomers believe that the explosion that launched LP 40-365 into flight was relatively weak and, apparently, partially preserved the remnants of both stars of the dead system. Perhaps someday we will also find the former neighbor LP 40-365.

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