![]() On the other hand, an absolute magnitude is the brightness of the object 10 parsecs (32.6 light-years) away from it. ![]() This star has an apparent magnitude that varies between 4.2 to 6.2, which means it's visible with the naked eye, despite located very far away from us. VisibilityĪn apparent magnitude is the brightness of something as seen from Earth. Currently, it is burning helium through this so-called "triple-alpha process" in its core. It is thought that Rho Cas is becoming hotter. The luminosity remains about the same during the outbursts at 500,000 Suns, but the radiation output redshifts.Īlthough carbon and oxygen have been burned and depleted, the Rho Cas' surface have much more heavy elements than on the Sun. It pulsates irregularly, causing small changes in brightness.Įvery 50 years, it undergoes a large outburst, blowing off significant layers of its atmosphere, causing a significant drop of temperature by 1,500 K (1,230☌) and brightness by 1.5 magnitudes. Usually, Rho Cas has a temperature of around 7,000 K (6,730☌) and a diameter of approximately 696 million kilometers. Rho Cassiopeiae usually loses mass around 10 -6 (0.000001) solar masses every single year, hundreds of millions of times the rate of its stellar wind. They are thought to form from main-sequence stars tens of times the mass of our Sun. Since they are very rare, we know very little about them. Only 15 yellow hypergiants are known in our galaxy, Milky Way. Rho Cassiopeiae is a yellow hypergiant, one of the rarest stars known. Rho Cassiopeiae is one of the most luminous stars known, almost reaching the Eddington luminosity limit (the maximum luminosity that stars can achieve). A Bayer designation is a Greek letter followed by the constellation name. Johann Bayer assigned the Bayer designation in his star catalog Uranometria. Rho Cassiopeiae (ρ Cassiopeiae) is the Bayer designation for this star. The star's nature was finally known to be a large and luminous but unstable star, constantly pulsing and losing mass and sometimes obscured by intense periods of mass loss. įor a long time, the nature of Rho Cas remained unknown. The light spectrum of this star showed features of a red giant star rather than the previous yellow-white dwarf class. The peculiarity was thought to be an expanding shell of gas around the star. Rho Cassiopeiae was first described as variable in 1901 and was only classified as "pec.", which is short for 'peculiar'. This star is visible with to naked eye due to its apparent magnitude of -9.5, which means it's very likely been recognized during the Ancient times, or even prehistoric eras.
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