The Argus sector was a region of space.
In 2370, the USS Enterprise-D was originally assigned to this sector, but Admiral Chekote allowed the Enterprise to postpone its mission there and search for a band of mercenaries which had apparently murdered Captain Picard. (TNG: "Gambit, Part I")
This sector was only mentioned in dialogue.
According to StarTrek.com
, this sector might have been named for the star