XTE J1739-285

XTE J1739−285 is a neutron star,^[2] in the constellation Ophiuchus, situated approximately 39,000 light-years from Earth. It was first observed on 19 October 1999 by NASA's Rossi X-ray Timing Explorer satellite.

XTE J1739−285

Observation data Epoch J2000      Equinox J2000
Constellation	Ophiuchus
Right ascension	17h 39m 53.95s
Declination	−28° 29′ 46.8″
Characteristics
Spectral type	Q
Variable type	None
Astrometry
Distance	39,000 Ly
Details
Mass	1.51[1] M☉
Radius	10.9 km
Other designations
SWIFT J1740.6−2821B
Database references
SIMBAD	data

It had previously been claimed that XTE J1739−285 was the fastest-spinning celestial body yet known, with a frequency of 1122 Hz.^[3] However, a re-analysis of these data by other astronomers has been unable to reproduce this result.^[4]

XTE J1739−285 has been proposed as a possible quark star, as well as 3C 58.

References

1. Zhang, C. M; Yin, H. X; Zhao, Y. H; Wei, Y. C; Li, X. D (2007). "Does Submillisecond Pulsar XTE J1739−285 Contain a Weak Magnetic Neutron Star or Quark Star?". Publications of the Astronomical Society of the Pacific. 119 (860): 1108. arXiv:0708.3566. Bibcode:2007PASP..119.1108Z. doi:10.1086/522796. S2CID 15651718.
2. Low mass X-ray binary
3. Evidence of 1122 Hz X-Ray Burst Oscillations from the Neutron Star X-Ray Transient XTE J1739–285
4. See footnote 1 of Chakrabarty, D; Wijnands, Rudy; Altamirano, Diego; Soleri, Paolo; Degenaar, Nathalie; Rea, Nanda; Casella, Piergiorgio; Patruno, Alessandro; Linares, Manuel (2008). "The spin distribution of millisecond X-ray pulsars". American Institute of Physics Conference Series. 1068: 67. arXiv:0809.4031. Bibcode:2008AIPC.1068...67C. doi:10.1063/1.3031208. S2CID 14585824.