4U 1700-37

4U 1700-37 is one of the stronger binary X-ray sources in the sky, and is classified as a high-mass X-ray binary. It was discovered by the Uhuru satellite. The "4U" designation refers to the Fourth (and final) Uhuru catalog.
It is associated with a bright (6.53 V magnitude) blue supergiant star HD 153919, which is orbited by an accreting compact object that must be either a neutron star or a black hole. The X-ray source is eclipsed by the star every ~3.4 days, but no pulsations have yet been observed.
The source is one of the ten brightest persistent X-ray sources in the 10-100 keV hard X-ray energy region.

Evidence of Compton cooling during an X-ray flare recorded by the Chandra X-ray telescope strongly suggests that the X-ray source is a neutron star; if verified it would be among the most massive known, and near the boundary of the theoretical maximum.

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Category:Binary stars
Scorpii, V884
Category:Durchmusterung objects
153919
083499
Category:Neutron stars
Category:O-type supergiants
Category:Rotating ellipsoidal variables
Category:X-ray binaries

Category:Scorpius (constellation)