6 Cassiopeiae (6 Cas) is a double star in the constellation Cassiopeia.

6 Cassiopeiae
Cassiopeia constellation map.svg
Red circle.svg
Location of 6 Cassiopeiae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
Right ascension  23h 48m 50.171s[1]
Declination +62° 12′ 52.26″[1]
Apparent magnitude (V) +5.43[2] (5.34 - 5.45[3])
Spectral type A2.5 Ia+[4]
U−B color index −0.02[2]
B−V color index +0.67[2]
Variable type α Cyg[3]
Proper motion (μ) RA: −3.57 ± 0.35[1] mas/yr
Dec.: −1.57 ± 0.33[1] mas/yr
Parallax (π)0.53 ± 0.37[1] mas
Distance2,510[5] pc
Absolute magnitude (MV)−8.30[6]
Mass22.0[6] M
Radius217[6] R
Luminosity200,000[7] L
Surface gravity (log g)1.59[8] cgs
Temperature10,023 ± 227[8] K
Metallicity [Fe/H]0.29[8] dex
Rotational velocity (v sin i)50[6] km/s
Other designations
6 Cas, V566 Cas, HR 9018, HD 223385, BD+61°2533, HIP 117447, SAO 20869
Database references


6 Cassiopeiae A is a white A2.5 type hypergiant. It is about 25 times as massive as the Sun and 200,000 times as luminous. The star is slightly and erratically variable, an Alpha Cygni variable.

6 Cas A has a number of close companions, most notably an 8th magnitude O class bright giant at only 1.5". Its spectral type is O9.75 and its absolute magnitude is −5.8.[9] Both are considered to be members of the Cassiopeia OB5 stellar association at a distance of around 8,000 light-years.[10]


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.[11] It has the variable star designation V566 Cassiopeiae.[3]


  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
  2. ^ a b c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
  3. ^ a b c 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: B/gcvs. Bibcode:2009yCat....102025S.
  4. ^ Chentsov, E. L.; Ermakov, S. V.; Klochkova, V. G.; Panchuk, V. E.; Bjorkman, K. S.; Miroshnichenko, A. S. (2003). "An atlas of spectra of B6-A2 hypergiants and supergiants from 4800 to 6700Å". Astronomy and Astrophysics. 397 (3): 1035–1042. Bibcode:2003A&A...397.1035C. doi:10.1051/0004-6361:20021430. ISSN 0004-6361.
  5. ^ Mel'Nik, A. M.; Efremov, Yu. N. (1995). "A new list of OB associations in our galaxy". Astronomy Letters. 21 (1): 10. Bibcode:1995AstL...21...10M.
  6. ^ a b c d Verdugo, Eva; Talavera, Antonio; Gómez De Castro, Ana I.; Henrichs, Huib F. (2003). "Search for magnetic fields in A-type supergiants". A Massive Star Odyssey: From Main Sequence to Supernova. 212: 255. Bibcode:2003IAUS..212..255V.
  7. ^ Achmad, L.; Lamers, H. J. G. L. M.; Pasquini, L. (1997). "Radiation driven wind models for A, F and G supergiants". Astronomy and Astrophysics. 320: 196. Bibcode:1997A&A...320..196A.
  8. ^ a b c Prugniel, P.; Vauglin, I.; Koleva, M. (2011). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics. 531: A165. arXiv:1104.4952. Bibcode:2011A&A...531A.165P. doi:10.1051/0004-6361/201116769.
  9. ^ Barsukova, E. A.; Chentsov, E. L. (1990). "The atmosphere of the supergiant 6 Cas. IV. The spectrum and radial velocities of the visual companion". Astrofiz. Issled. Izv. Spets. Astrofiz. Obs. 29: 101. Bibcode:1990AISAO..29..101B.
  10. ^ Bartaya, R. A.; Chargeishvili, K. B.; Chentsov, E. L.; Shkhagosheva, Z. U. (1994). "Hypergiant 6 Cas and association Cas OB5". Bulletin of the Special Astrophysical Observatory. 38: 103. Bibcode:1994BSAO...38..103B.
  11. ^ Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.

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