HD 153919 and the X-ray source 2U 1700-37.

HD 153919 is the prime optical candidate for the X-ray source 2U 1700-37. Radcliffe spectra show the star to be an O f star with a strong line of C III. The radial velocities indicate that the star has an expanding atmosphere. The star is both a radial velocity and spectrum variable. Attention is drawn to some very broad, variable emission features underlying the main stellar spectrum.