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
^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. S2CID15651718.