QV Normae, also known as Norma X-2, is a high mass

X-ray binary X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively common main sequence star), to the other component, called the ''acc ...

star system in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Norma Norma may refer to: * Norma (given name), a given name (including a list of people with the name) ** Norma Lizbeth Ramos, a Mexican bullying victim Astronomy *Norma (constellation) * 555 Norma, a minor asteroid * Cygnus Arm or Norma Arm, a spiral ...

. It varies between

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

s of 16.19 and 16.31. 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 The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

and a neutron star initially estimated at around 1.4

solar mass The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...

es, later revised to 0.8 solar masses. The

stellar wind A stellar wind is a flow of gas ejected from the stellar atmosphere, upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spheri ...

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.

References

{{DEFAULTSORT:QV Normae Normae, QV Norma (constellation) X-ray binaries Astronomical X-ray sources