Sigma Cygni

σ Cygni
Location of σ Cygni (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 21h 17m 24.95244s[1]
Declination +39° 23′ 40.8528″[1]
Apparent magnitude (V) 4.233[2]
Characteristics
Spectral type B9 Iab[2]
U−B color index −0.386[2]
B−V color index +0.123[2]
Astrometry
Radial velocity (Rv)−5.30 ± 0.40[3] km/s
Proper motion (μ) RA: −0.13[1] mas/yr
Dec.: −3.58[1] mas/yr
Parallax (π)1.13 ± 0.19[1] mas
Distance1,000[4] pc
Absolute magnitude (MV)−6.18[4]
Details
Mass15[5] M☉
Radius54[4] R☉
Luminosity52,500[6] L☉
Surface gravity (log g)1.85[2] cgs
Temperature10.800[2] K
Metallicity0.0[6]
Rotational velocity (v sin i)14[2] km/s
Age16[6] Myr
Other designations
67 Cyg, HD 202850, HR 8143, HIP 105102
Database references
SIMBADdata

Sigma Cygni (σ Cyg) is a blue supergiant star in the constellation Cygnus. Its apparent magnitude is 4.2. It belongs to the Cygnus OB4 stellar association and is located approximately 3,300 light years away from Earth.

Because of its location at the galactic disk, σ Cyg is obstructed by interstellar dust and is reddened by around 0.2 magnitudes and loses about 0.6 magnitudes at visual wavelengths.[2] Allowing for this, the star is over 50,000 times as luminous as the sun.

Spectral analysis of the star showed that photospheric SiII and HeI lines display a simultaneous, periodic variability. The periodicity was calculated at 1.59 hours in all three lines and it might be the result of stellar oscillations.[7] No clear variation in the brightness has been detected.[8]

References

  1. 1 2 3 4 5 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 5 6 7 8 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.
  3. ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  4. 1 2 3 Markova, N.; Puls, J. (2008). "Bright OB stars in the Galaxy. IV. Stellar and wind parameters of early to late B supergiants". Astronomy and Astrophysics. 478 (3): 823. arXiv:0711.1110. Bibcode:2008A&A...478..823M. doi:10.1051/0004-6361:20077919.
  5. ↑ Przybilla, N.; Firnstein, M.; Nieva, M. F.; Meynet, G.; Maeder, A. (2010). "Mixing of CNO-cycled matter in massive stars". Astronomy and Astrophysics. 517: A38. arXiv:1005.2278. Bibcode:2010A&A...517A..38P. doi:10.1051/0004-6361/201014164.
  6. 1 2 3 Tanrıverdi, Taner (2013). "Elemental abundances of the supergiant stars σ Cygnus and η Leonis". New Astronomy. 25: 50. arXiv:1512.04557. Bibcode:2013NewA...25...50T. doi:10.1016/j.newast.2013.03.013.
  7. ↑ Kraus, M.; Tomić, S.; Oksala, M. E.; Smole, M. (June 2012). "Detection of a 1.59 h period in the B supergiant star HD 202850". Astronomy and Astrophysics. 542: L32. arXiv:1205.5391. Bibcode:2012A&A...542L..32K. doi:10.1051/0004-6361/201219319.
  8. ↑ Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331: 45. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.
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