LS 5039

LS 5039 is a binary system in the constellation of Scutum. It has an apparent magnitude of 11.27, and it is about 8,200 light-years away.
The "LS" in the system's name refers to the Luminous Stars catalogue which was published by Charles Bruce Stephenson and Nicholas Sanduleak in 1971. In 2001, J. Simon Clark et al. announced that LS 5039 varies in brightness. For that reason, it was given the variable star designation V479 Scuti, in 2006. It is considered to be a possible microquasar.
LS 5039 consists of a massive O-type main-sequence star, and a compact object that emits HE and VHE gamma rays. It is one of the only three known star systems of this kind, together with LS I +61 303 and PSR B1259-63. The two objects orbit each other every 3.9 days, along a moderately eccentric orbit. Additionally, it is one of the few massive X-ray binaries known to be associated with radio emission.