6 Cassiopeiae

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6 Cassiopeiae
Cassiopeia constellation map.svg
Red circle.svg
Location of 6 Cassiopeiae (circled)
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cassiopeia [1]
Right ascension 23h 48m 50.171s [2]
Declination +62° 12′ 52.26″ [2]
Apparent magnitude  (V)5.34 - 5.45 [3]
Characteristics
Spectral type A2.5 Ia+ [4]
U−B color index −0.02 [5]
B−V color index +0.67 [5]
Variable type α Cyg [3]
Astrometry
Proper motion (μ)RA: −3.300 [2] mas/yr
Dec.: −1.590 [2] mas/yr
Parallax (π)0.4264±0.0660  mas [2]
Distance approx. 8,000  ly
(approx. 2,300  pc)
Absolute magnitude  (MV)−8.30 [6]
Details
Mass 22.0 [6]   M☉
Radius 193 [6]   R☉
Luminosity 200,000 [7]   L☉
Surface gravity (log g)1.59 [8]   cgs
Temperature 10,023±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
SIMBAD data

6 Cassiopeiae (6 Cas) is a white hypergiant in the constellation Cassiopeia, and a small-amplitude variable star. At 5th magnitude, it is visible to the naked eye under good observing conditions.

Contents

System

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. 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. However, later publications have given more conventional hypergiant spectral types such as B9Ia+ and A3Ia+. [9]

A light curve for V566 Cassiopeiae from Hipparcos data, plotted as a function of phase assuming the dominant period found by Koen and Eyer (2002) V566CasLightCurve.png
A light curve for V566 Cassiopeiae from Hipparcos data, plotted as a function of phase assuming the dominant period found by Koen and Eyer (2002)

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. [12] Both are considered to be members of the Cassiopeia OB5 stellar association at a distance of around 8,000 light-years, [13] along with several other nearby stars. [14] Gaia parallaxes of the nearby stars suggest a mean distance to the association of about 9,000 light years. [14]

Variability

Manali Kallat Vainu Bappu discovered that the star's brightness varies, in 1958. [15] 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. [10] It has the variable star designation V566 Cassiopeiae. [3]

References

  1. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971 . Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN   1562-6873. ISSN   1063-7737. S2CID   119257644.
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 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. 1 2 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.
  6. 1 2 3 4 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. 1 2 3 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. S2CID   54940439.
  9. ↑ Skiff, B. A. (2014). "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009- )". VizieR On-line Data Catalog. Bibcode:2014yCat....1.2023S.
  10. 1 2 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 . S2CID   10505995.
  11. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  12. ↑ 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.
  13. ↑ 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.
  14. 1 2 Maíz Apellániz, J.; Barbá, R. H.; Fariña, C.; Sota, A.; Pantaleoni González, M.; Holgado, G.; Negueruela, I.; Simón-Díaz, S. (2021). "Lucky spectroscopy, an equivalent technique to lucky imaging". Astronomy & Astrophysics. 646: A11. arXiv: 2011.12250 . doi: 10.1051/0004-6361/202039479 . S2CID   227151330.
  15. ↑ Bappu, M. K. V. (June 1959). "The light variation of 6 Cassiopeiae". The Observatory. 79: 100–102. Bibcode:1959Obs....79..100B.
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