S Cassiopeiae

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S Cassiopeiae
Cassiopeia constellation map.svg
Location of S Cas
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 01h 19m 41.99s[1]
Declination 72° 36′ 40.8″[1]
Apparent magnitude (V) +7.9 – +16.1[2]
Spectral type S3,4 – S5,8[3]
Variable type Mira[2]
Distance 1,860 – 2,770 ly
(570[4] - 850[5] pc)
Radius 930[6] R
Luminosity 8,000[4] L
Temperature 1,800[4] K
Other designations
S Cas, HD 7769, BD+71°66, 2MASS J01194198+7236407, GSC 04305-01322, IRAS 01159+7220, IRC+70024, AAVSO 0112+72
Database references

S Cassiopeiae (S Cas, HD 7769) is a mira variable and S-type star in the constellation Cassiopeia.


In the absence of a measure of its parallax by the Hipparcos satellite, its distance from the solar system is estimated between 1,860 and 2,770 light-years.

Spectral type[edit]

With a spectral type of S3,4e-S5,8e, S Cassiopeiae is an S-type star similar to χ Cygni; these are asymptotic giant branch (AGB) stars similar to those of class M except that the dominant spectral bands of metal oxides are formed by metals of the fifth period of the periodic table as zirconium or yttrium. Another feature of this class of stars is the high mass loss; in the case of S Cassiopeiae it is estimated at 3.5×10−6 M per year.[3]


S Cassiopeiae has a radius of 930 solar radii; if placed at the center of the Solar System, it would extend past the orbit of Mars and the Asteroid Belt. Its effective temperature is 1,800 K and its bolometric luminosity is 8,000 times that of the sun.

S Cassiopeiae is a variable Mira, a pulsating variable star whose visual brightness varies over several magnitudes with a somewhat regular period and amplitude. Its visual magnitude varies between +7.9 and +16.1 over an average period of 612.43 days. Mira variables are stars in the last stages of evolution whose instability comes from pulsations in its surface, causing changes in color and brightness. Some of them, including S Cassiopeiae show SiO maser emission.[7]

See also[edit]


  1. ^ a b Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally published in: 2003yCat.2246....0C. 2246. Bibcode:2003yCat.2246....0C. 
  2. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S. 
  3. ^ a b Ramstedt, S.; Schöier, F. L.; Olofsson, H.; Lundgren, A. A. (2006). "Mass-loss properties of S-stars on the AGB". Astronomy and Astrophysics. 454 (2): L103. arXiv:astro-ph/0605664Freely accessible. Bibcode:2006A&A...454L.103R. doi:10.1051/0004-6361:20065285. 
  4. ^ a b c Ramstedt, S.; Olofsson, H. (2014). "The 12CO/13CO ratio in AGB stars of different chemical type. Connection to the 12C/13C ratio and the evolution along the AGB". Astronomy & Astrophysics. 566: A145. arXiv:1405.6404Freely accessible. Bibcode:2014A&A...566A.145R. doi:10.1051/0004-6361/201423721. 
  5. ^ Guandalini, R.; Busso, M. (2008). "Infrared photometry and evolution of mass-losing AGB stars. II. Luminosity and colors of MS and S stars". Astronomy and Astrophysics. 488 (2): 675. arXiv:0806.4591Freely accessible. Bibcode:2008A&A...488..675G. doi:10.1051/0004-6361:200809932. 
  6. ^ "Circumstellar molecular line emission from S-type AGB stars: mass-loss rates and SiO abundances". Astronomy and Astrophysics. 499 (2): 515–527. 2009. arXiv:0903.1672Freely accessible. Bibcode:2009A&A...499..515R. doi:10.1051/0004-6361/200911730. 515-527. 
  7. ^ Herpin, F.; Baudry, A.; Thum, C.; Morris, D.; Wiesemeyer, H. (2006). "Full polarization study of SiO masers at 86 GHz". Astronomy and Astrophysics. 450 (2): 667. arXiv:astro-ph/0601098Freely accessible. Bibcode:2006A&A...450..667H. doi:10.1051/0004-6361:20054255.