White dwarf with fastest spin: one rotation every 25 seconds

The white dwarf is pulling gaseous plasma from a nearby companion star and flinging it into space at around 3,000 kilometres per second.

A white dwarf star that completes a full rotation once every 25 seconds is the fastest spinning confirmed white dwarf, according to a team of astronomers.

They have shown that it is an extremely rare example of a magnetic propeller system: The white dwarf is pulling gaseous plasma from a nearby companion star and flinging it into space at around 3,000 kilometres per second. It is only the second magnetic propeller white dwarf to have been identified in over 70 years, thanks to a combination of powerful and sensitive instruments.

Put into context, one rotation of the planet Earth takes 24 hours, while the equivalent on J0240+1952 is a mere 25 seconds. That’s almost 20% faster than the confirmed white dwarf with the most comparable spin rate, which completes a rotation in just over 29 seconds.

The study was led by the University of Warwick with the University of Sheffield. It has been published in the journal Monthly Notices of the Royal Astronomical Society: Letters.

A white dwarf is a star that has burnt up all of its fuel and shed its outer layers, now undergoing a process of shrinking and cooling over millions of years. This particular star, named LAMOST J024048.51+195226.9 — or J0240+1952 —is the size of the Earth but is thought to be at least 200,000 times more massive. It is part of a binary star system; its immense gravity is pulling material from its larger companion star in the form of plasma.

Source: University of Warwick

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