Rho Cassiopeiae (ρ Cas / ρ Cassiopeiae) is a yellow hypergiant in the constellation Cassiopeia. The solar luminosity, L_\odot is a unit of Luminosity ( power emitted in the form of Photons conventionally used by Astronomers to Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic In Astronomy and Physical cosmology, the metallicity of an object is the proportion of its matter made up of Chemical elements other than Hydrogen Stellar rotation is the angular motion of a Star about its axis A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun A star catalogue, or star catalog, is an Astronomical catalogue that lists Stars In Astronomy, many stars are referred to simply by catalogue The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars or Yale Bright Star Catalogue, is a Star catalogue that lists of all stars of In Astronomy, Durchmusterung or Bonner Durchmusterung ( BD) is the usual name for three comprehensive astrometric Star catalogues The Henry Draper Catalogue ( HD) is an Astronomical Star catalogue published between 1918 and 1924 giving Spectroscopic classifications The Smithsonian Astrophysical Observatory Star Catalog is an astrometric Star catalogue. The Catalogue of Fundamental Stars is a series of six astrometric catalogues of high precision positional data for a small selection of stars to define a celestial reference The Hipparcos and Tycho Catalogues (Tycho-1 are the primary products of the European Space Agency 's astrometric mission Hipparcos. For the missile mounting see Mistral missile SIMBAD (the S et of I dentifications M easurements and B ibliography for Generally speaking a yellow hypergiant is a very massive Star with an extended Atmosphere, which can be classified as spectral class from late A to K with a mass Cassiopeia ( colloquially /ˌkæsiˈoʊpiə/ is a northern Constellation which Greek mythology considered to represent the vain queen Cassiopeia who boasted It is about 11,650 light-years away, yet can still be seen by the naked eye (in the Northern Hemisphere only), as it is 550,000 times as luminous as the Sun. A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by Northern Hemisphere is the half of a Planet that is North of the Equator —the word hemisphere literally means 'half ball' Luminosity has different meanings in several different fields of science The Sun (Sol is the Star at the center of the Solar System. Its surface diameter is 450 times that of our sun's. On average, it has an absolute magnitude of −7. In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard 5, making it one of the most luminous stars known. Below is a list of Stars arranged in order of increasing absolute Bolometric magnitude (decreasing Luminosity) Even though its surface temperature is similar to the Sun, its comfort zone for an Earthlike planet would be 450AU, which is more than 10 times the distance from the sun to Pluto. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the Being a yellow hypergiant, it is one of the rarest types of stars, one of only seven that are currently known.

Rho Cassiopeiae is somewhat unstable in its luminosity. Instability in systems is generally characterized by some of the Outputs or internal states growing without Bounds. Luminosity has different meanings in several different fields of science Its apparent magnitude is currently about 4. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 5, but in 1946 it dimmed to 6th magnitude, before returning to its previous brightness. Year 1946 ( MCMXLVI) was a Common year starting on Tuesday (link will display full 1946 calendar of the Gregorian calendar. This happened again in 2000–2001, when it produced one of the largest outbursts known, ejecting 3% of a solar mass, the equivalent of 10,000 Earths. 2000 ( MM) was a Leap year that started on Saturday of the Common Era, in accordance with the Gregorian calendar. Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 During the summer of 2000 it was observed (by the William Herschel Telescope) to have cooled from 7000 to 4000 degrees in the course of a few months. The William Herschel Telescope or WHT was first conceived in the late 1960s when the Anglo-Australian Observatory was being designed It seems to undergo these eruptions approximately once every 50 years (data suggests previous eruptions in 1893 and 1945).

Astronomers predict Rho Cassiopeiae may become a supernova in the near future because it will soon have consumed most of its nuclear fuel. A supernova (plural supernovae or supernovas) is a stellar Explosion.

External links

• Press release from the William Herschel Telescope team about their findings.
• Rho Cassiopeiae fact sheet
• David Darling site
• Big and Giant Stars: Rho Cassiopeiae