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Nu Cephei
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Nu Cephei is a blue-hued variable star in the northern constellation Cepheus. Its name is a Bayer designation that is Latinized from ν Cephei, and abbreviated Nu Cep or ν Cep. This is a pulsating α Cygni variable star that ranges in apparent visual magnitude from 4.25 to 4.35.[3] This is bright enough to make it visible to the naked eye as a fourth-magnitude star. Distance estimates place it at about 3,500 light-years from Earth. It is drifting closer to the Sun with a line of sight velocity component of −26 km/s.[6]
ν Cephei is a member of the Cepheus OB2 stellar association,[4] which includes stars such as μ Cephei and VV Cephei.[10]
Properties
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The stellar classification of this star is A2Iab,[2] matching an evolved blue supergiant. It began life as an approximately 20 M☉[8][4] main sequence star around eight million years ago. Nu Cephei has exhausted its core hydrogen and expanded and cooled into a supergiant. Elemental abundance analyses indicate that it has not yet spent time as a red supergiant, which would have brought about convection of fusion products to the surface in a dredge-up.[4]
ν Cephei is currently about 15 times as massive as the sun, 137 times as large, and 100,000 times as luminous.[8] Its large size and luminosity cause it to be somewhat unstable and produce irregular pulsations. This is a common feature of class A and B supergiants, which are grouped as α Cygni variable stars. Variability was first reported by Helmut Abt in 1957.[12] The brightness changes by at most a tenth of a magnitude.[3] A variety of values for the variability period have been published, including 5 to 10 days,[13] 7.6 days[14][12] and 90 days.[15]
References
[edit]- ^ a b c d 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.
- ^ a b c d e f g h Firnstein, M.; Przybilla, N. (2012). "Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters". Astronomy & Astrophysics. 543: A80. arXiv:1207.0308. Bibcode:2012A&A...543A..80F. doi:10.1051/0004-6361/201219034. S2CID 54725386.
- ^ a b c d 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.
- ^ a b c d e Yüce, Kutluay (2005). "Spectral Analysis of 4 Lacertae and ν Cephei". Baltic Astronomy. 14: 51. Bibcode:2005BaltA..14...51Y.
- ^ a b c d 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. Bibcode:2002yCat.2237....0D.
- ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ Verdugo, E.; et al. (1999). "Understanding A-type supergiants. II. Atmospheric parameters and rotational velocities of Galactic A-type supergiants". Astronomy and Astrophysics. 346: 819. Bibcode:1999A&A...346..819V.
- ^ a b c d e Firnstein, Markus (2010). Quantitative Spectroscopy of Galactic BA-Type Supergiants (Ph.D.). Erlangen, Nürnberg, Univ.
- ^ "nu. Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-01-30.
- ^ Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal. 38: 309. Bibcode:1978ApJS...38..309H. doi:10.1086/190559.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 27 September 2024.
- ^ a b Abt, Helmut A. (July 1957). "The Variability of Supergiants". Astrophysical Journal. 126: 138–151. Bibcode:1957ApJ...126..138A. doi:10.1086/146379.
- ^ Percy, J. R.; Welch, D. L. (August 1983). "Photometric variability of B- and A-type supergiants". Publications of the Astronomical Society of the Pacific. 95: 491–505. Bibcode:1983PASP...95..491P. doi:10.1086/131198.
- ^ Buscombe, W. (June 1974). "Variations in the spectra of A-type supergiants". The Observatory. 94: 120–122. Bibcode:1974Obs....94..120B.
- ^ "nu. Cep". The International Variable Star Index. AAVSO. Retrieved 29 September 2024.
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