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PSR J1748−2446ad
	; The location of PSR J1748-2446ad in the night sky. The pulsar is located in the center of the yellow square. It is too faint in this image to be visible against the background.; Credit: GALEX GR6/7 Data Release
Observation data; Epoch J2000 Equinox J2000
Constellation	Sagittarius
Right ascension	17h 48m 04.9s
Declination	−24° 46′ 04″
Characteristics
Spectral type	Pulsar
U−B color index	?
B−V color index	?
Variable type	None
Astrometry
Distance	18,000 Ly
Details
Mass	<2 M☉
Radius	<16 km
Rotation	0.00139595482(6) s; 716.35556(3) Hz
Age	≥2.5×107 years
Database references
SIMBAD	data

PSR J1748−2446ad is the fastest-spinning pulsar known, at 716 Hz (times per second),^[2] or 42,960 revolutions per minute. This pulsar was discovered by Jason W. T. Hessels of McGill University on November 10, 2004, and confirmed on January 8, 2005.

If the neutron star is assumed to contain 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 in the system is at least 0.14 solar masses, with a radius of 5–6 solar radii. Hessels and collaborators state that the companion may be a "bloated main-sequence star, possibly still filling its Roche Lobe". Hessels and collaborators go on to speculate that gravitational radiation from the pulsar might be detectable by LIGO.^[2]

References

^ Ortolani, S.; Barbuy, B.; Bica, E.; Zoccali, M.; Renzini, A. (2007). "Distances of the bulge globular clusters Terzan 5, Liller 1, UKS 1, and Terzan 4 based on HST NICMOS photometry". Astronomy and Astrophysics. 470 (3): 1043–1049. arXiv:0705.4030. Bibcode:2007A&A...470.1043O. doi:10.1051/0004-6361:20066628. S2CID 18360940.
^ ^a ^b ^c Hessels, J. W. T.; Ransom, S. M.; Stairs, I. H.; Freire, P. C.; Kaspi, V. M.; Camilo, F. (2006). "A Radio Pulsar Spinning at 716 Hz". Science. 311 (5769): 1901–1904. arXiv:astro-ph/0601337. Bibcode:2006Sci...311.1901H. doi:10.1126/science.1123430. PMID 16410486. S2CID 14945340.