QV Normae, also known as Norma X-2, is a high mass X-ray binary star system in the constellation Norma. It varies between apparent magnitudes of 16.19 and 16.31.[1]
The X-ray source was first identified in the early 1970s. The nature of the system was discovered in 1978 by astronomers who aligned a visual source of a reddened hot blue-white star with the X-ray source 4U 1538 - 52. The components are a blue-white supergiant estimated to have a mass around 20 times that of the Sun and a neutron star initially estimated at around 1.4 solar masses,[2] later revised to 0.8 solar masses. The stellar wind from the more massive star is drawn to the magnetic poles of neutron star, forming an accretion column and producing X-rays. The system has been estimated to lie anywhere from 4500 to 6500 parsecs (15,000-20,000 light-years) from Earth.[3]