PSR J1748−2446ad

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PSR J1748−2446ad
Location of PSR J1748-2446ad.png
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″
Spectral type Pulsar
U−B color index ?
B−V color index ?
Variable type None
Distance 18,000 Ly [1]
Mass<2 M
Radius<16 km
Rotation0.00139595482(6) s
716.35556(3) Hz
Age≥2.5×107 years
Database references

PSR J1748−2446ad is the fastest-spinning pulsar known, at 716 Hz,[2] 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.

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


  1. ^ 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.
  2. ^ 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.

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