GRO J1655-40

GRO J1655-40 is a binary in Scorpius made of an evolved F-type star and an unseen companion, apparently a black hole of about six solar masses, that orbit each other every 2.6 days. Gas from the star is accreted by the black hole.

The Compton Gamma Ray Observatory discovered it on 27 July 1994. Like GRS 1915+105 it is a galactic microquasar with radio jets. Its distance is probably about 11,000 light-years, although a closer value near 2,800 light-years is not ruled out.