Cygnus OB2-12
Encyclopedia
Cygnus OB2-12 is an extremely bright blue hypergiant
Hypergiant
A hypergiant is a star with a tremendous mass and luminosity, showing signs of a very high rate of mass loss.-Characteristics:...

 with an absolute bolometric magnitude (all electromagnetic radiation) of -12.2, which approaches the upper limit believed possible for normal single stars.
This makes the star more than 6 million times brighter than the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

, and among the most luminous stars known in the galaxy
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

.

It is a member of the Cyg OB2 Association
Cygnus OB2
Cygnus OB2 is one of the largest young clusters of stars in our Galaxy, and home to some of the most massive stars known, including Cyg OB2 #8 and Cyg OB2 #12, one of the most luminous stars known. The region is embedded within a wider region of star formation known as Cygnus X, which is one of the...

, a cluster of young massive stars about 5000 light years away in Cygnus, and resides in a region of the Galaxy from which visible light is heavily absorbed by interstellar dust when viewed from the Earth.
Were it not for the dust extinction
Extinction (astronomy)
Extinction is a term used in astronomy to describe the absorption and scattering of electromagnetic radiation by matter between an emitting astronomical object and the observer. Interstellar extinction—also called Galactic extinction, when it occurs in the Milky Way—was first...

, the star would have a visual magnitude about 1.5, nearly as bright as Deneb
Deneb
Deneb is the brightest star in the constellation Cygnus and one of the vertices of the Summer Triangle. It is the 19th brightest star in the night sky, with an apparent magnitude of 1.25. A blue-white supergiant, Deneb is also one of the most luminous nearby stars...

 (Alpha Cygni), but because of the dust, the observed visual magnitude is 11.4, so that it requires binoculars or a small telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

to be seen.
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