Nu Cephei

ν Cephei
Location of ν Cephei (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cepheus
Right ascension 21h 45m 26.925s[1]
Declination +61° 07′ 14.900″[1]
Apparent magnitude (V) 4.289[2] (4.25 to 4.35[3])
Characteristics
Evolutionary stage Blue supergiant[4]
Spectral type A2Iab[2]
Apparent magnitude (U) 4.94[5]
Apparent magnitude (B) 4.81[5]
Apparent magnitude (J) 3.14[5]
Apparent magnitude (K) 2.85[5]
U−B color index +0.119[2]
B−V color index +0.518[2]
Variable type Alpha Cygni[3]
Astrometry
Radial velocity (Rv)−25.90[6] km/s
Proper motion (μ) RA: −3.545 mas/yr[1]
Dec.: −2.025 mas/yr[1]
Parallax (π)0.9321±0.0865 mas[1]
Distance3,500 ± 300 ly
(1,070 ± 100 pc)
Absolute magnitude (MV)−6.82[7]
Details
Mass15.4[8] M☉
Radius137[8] R☉
Luminosity102,000[8] L☉
Surface gravity (log g)1.35[2] cgs
Temperature8,800[2] K
Rotational velocity (v sin i)15[2] km/s
Age8[4] Myr
Other designations
ν Cep, 10 Cephei, BD+60°2288, FK5 1572, HD 207260, HIP 107418, HR 8334, SAO 19624[9]
Database references
SIMBADdata

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

A light curve for Nu Cephei, plotted from TESS data,[11]

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

  1. ^ 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.
  2. ^ 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.
  3. ^ 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.
  4. ^ a b c d e Yüce, Kutluay (2005). "Spectral Analysis of 4 Lacertae and ν Cephei". Baltic Astronomy. 14: 51. Bibcode:2005BaltA..14...51Y.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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.
  8. ^ a b c d e Firnstein, Markus (2010). Quantitative Spectroscopy of Galactic BA-Type Supergiants (Ph.D.). Erlangen, Nürnberg, Univ.
  9. ^ "nu. Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-01-30.
  10. ^ 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.
  11. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 27 September 2024.
  12. ^ a b Abt, Helmut A. (July 1957). "The Variability of Supergiants". Astrophysical Journal. 126: 138–151. Bibcode:1957ApJ...126..138A. doi:10.1086/146379.
  13. ^ 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.
  14. ^ Buscombe, W. (June 1974). "Variations in the spectra of A-type supergiants". The Observatory. 94: 120–122. Bibcode:1974Obs....94..120B.
  15. ^ "nu. Cep". The International Variable Star Index. AAVSO. Retrieved 29 September 2024.

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