6 Cassiopeiae (6 Cas) is a white

hypergiant A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MK ...

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 origins of the e ...

Cassiopeia, and a small-amplitude

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

System

6 Cassiopeiae A is a white A2.5 type hypergiant. It is about 25 times as massive as the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

and 200,000 times as luminous. The star is slightly and erratically variable, an

Alpha Cygni variable Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant stars of spectral types B or A. Variations in ...

. Not all sources consider 6 Cas to be a hypergiant. It is thought that the "+" in an early A3 Ia+ spectral classification referred to indications of additional spectral features from a possible companion rather than the more modern indication of a hypergiant

luminosity class In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

. However, later publications have given more conventional hypergiant spectral types such as B9Ia⁺ and A3Ia⁺. V566CasLightCurve

6 Cas A has a number of close companions, most notably an 8th magnitude O class bright giant at only . Its spectral type is O9.75 and its absolute magnitude is −5.8. Both are considered to be members of the Cassiopeia OB5

stellar association A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more stars. The stars share a common origin, but have become gravitationally u ...

at a distance of around 8,000

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s, along with several other nearby stars.

Gaia In Greek mythology, Gaia (; from Ancient Greek , a poetical form of , 'land' or 'earth'),, , . also spelled Gaea , is the personification of the Earth and one of the Greek primordial deities. Gaia is the ancestral mother—sometimes parthenog ...

parallaxes of the nearby stars suggest a mean distance to the association of about 9,000 light years.

Variability

6 Cas A is an α Cyg variable, pulsating erratically between 5.34 and 5.45. The strongest period detected in one study was 37 days. It has the

variable star designation In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constell ...

V566 Cassiopeiae.

References

External links

6 Cassiopeiae
at Jim Kaler's Stars {{Stars of Cassiopeia A-type hypergiants Cassiopeia (constellation) Cassiopeiae, 06 9018 117447 117447 BD+61 2533 Cassiopeiae, V566 Alpha Cygni variables Multiple stars O-type bright giants