White dwarf with fastest spin of one rotation in 25 seconds spotted

This is the second magnetic propeller that astronomers identified in over 70 years

A team of astronomers have confirmed that full rotation once in 25 seconds is the fastest spinning white dwarf star. The study was conducted by the University of Warwick with the University of Sheffield and has been published in the journal Monthly Notices of the Royal Astronomical Society: Letters.

White dwarf stars have medium to high mass and are the final evolutionary state of stars whose mass is not high enough to become a neutron star. The astronomers have shown the rotation of the white dwarf star as an extremely rare example of a magnetic propeller system. The star was drawing gaseous plasma from a nearby star and tossing it into space at 3,000 kilometers per second speed.

This is the second magnetic propeller that astronomers identified in over 70 years and is a combination of sensitive and powerful instruments. The new dwarf star is the 20 per cent faster than another confirmed white dwarf that completed a full rotation in just over 29 seconds. For the sake of comparison, one rotation of the planet Earth takes 24 hours.

White dwarf stars are stars that have burnt up all their energy and shed its outer layers and now are undergoing a cooling or shrinking process over million of years.

The new dwarf star named LAMOST J024048.51+195226.9 — or J0240+1952 —is the size of the Earth estimated to be 200,000 times more massive. It is part of a binary star system. The star’s immense gravity is pulling plasma material from its larger companion star and putting it to spin. The materials in a white dwarf star can no longer undergo fusion reactions, so the star has no source of energy.