The Fastest-Spinning Star

PSR J1748-2446ad is the fastest-spinning pulsar known, at 716 Hz, or 716 times per second. This pulsar was discovered by Jason W. T. Hessels of McGill University on November 10, 2004 and confirmed on January 8, 2005.

It has been calculated that the neutron star contains slightly less than two times the mass of the Sun, within the typical range of neutron stars. Its radius is constrained to be less than 16 km. At its equator it is spinning at approximately 24% of the speed of light, or over 70,000 km per second.

The pulsar is located in a globular cluster of stars called Terzan 5, located approximately 18,000 light-years from Earth in the constellation Sagittarius. It is part of a binary system and undergoes regular eclipses with an eclipse magnitude of about 40%. Its orbit is highly circular with a 26-hour period. The other object is about 0.14 solar masses, with a radius of 5–6 solar radii. Hessels states that the companion may be a "bloated main-sequence star, possibly still filling its Roche Lobe". Hessels goes on to speculate that gravitational radiation from the pulsar might be detectable by LIGO.

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