V354 Cephei

V354 Cephei
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
Right ascension 22h 33m 34.643s[1]
Declination +58° 53′ 47.05″[1]
Apparent magnitude (V) 10.82 to 11.35[2]
Characteristics
Spectral type M2.5 Iab[3]
B−V color index +3.18[4]
Variable type LC[2]
Astrometry
Distance~9,000[5] ly
(3,500 pc)
Absolute magnitude (MV)-7.57 (variable)[4]
Details
Radius1,520[6] R☉
Luminosity76,000[7] - 369,000[6] L☉
Surface gravity (log g)−0.5[6] cgs
Temperature3,650[6] K
Other designations
V354 Cep, Case 75, 2MASS J22333464+5853470, IRAS 22317+5838
Database references
SIMBADdata

V354 Cephei is a red supergiant star located within the Milky Way. It is an irregular variable located approximately 9,000 light-years away from the Sun, and is currently considered one of the largest known stars, with a radius estimate of 1,520 solar radii (1.06×109 km; 7.1 au). If it were placed in the center of the Solar System, it would extend to between the orbits of Jupiter and Saturn.

Identification

V354 Cephei is now clearly identified as a red supergiant variable star and included on surveys such as IRAS and 2MASS, but prior to its inclusion in the General Catalogue of Variable Stars in 1981, it was referred to only by its listings on relatively obscure catalogs.[8] It is too faint to be included in catalogs such as the Henry Draper Catalogue or Bonner Durchmusterung. It was included on a 1947 Dearborn Observatory survey as star 41575, but that ID is hardly ever used.[9]

V354 Cep has frequently been referred to as Case 75.[4][8] This is from one of several listings of cool stars made using the Burrell Schmidt telescope at the Warner and Swasey Observatory of Case Western Reserve University, although Case 75 is mistakenly identified as the nearby F3V star BD+58°2450.[10]

Distance

V354 Cep is too far away to have a measured parallax which would allow its distance to be determined directly. It is near the Cepheus OB1 stellar association and considered a likely member. This association is at a distance of approximately 3,500 parsecs.[11]

Properties

The luminosity, and hence the size, of V354 Cep are disputed. Levesque et al. 2005, find a high luminosity and consequently very large size of 1,520 R☉, making it one of the largest stars. From the same data, Mauron et al. 2011 derive a much smaller luminosity of 76,000 L☉, which implies a much smaller size around 690 R☉. They note the discrepancy but are unable to explain it.[7]

There are similar differences in the visual extinctions derived, between two and six magnitudes.[3][4]

See also

References

  1. 1 2 Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally published in: 2003yCat.2246....0C. 2246. Bibcode:2003yCat.2246....0C.
  2. 1 2 V354 Cep, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 12, 2010.
  3. 1 2 Verhoelst, T.; Van Der Zypen, N.; Hony, S.; Decin, L.; Cami, J.; Eriksson, K. (2009). "The dust condensation sequence in red supergiant stars". Astronomy and Astrophysics. 498: 127. arXiv:0901.1262Freely accessible. Bibcode:2009A&A...498..127V. doi:10.1051/0004-6361/20079063.
  4. 1 2 3 4 Levesque, Emily M.; Massey, Philip; Olsen, K. A. G.; Plez, Bertrand; Josselin, Eric; Maeder, Andre; Meynet, Georges (August 2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought". The Astrophysical Journal. 628 (2): 973–985. arXiv:astro-ph/0504337Freely accessible. Bibcode:2005ApJ...628..973L. doi:10.1086/430901.
  5. ↑ V354 Cephei is in the Cep OB1 association, which has an adopted estimated distance modulus of 12.2. See Tables 1 and 2, Levesque et al. 2005.
  6. 1 2 3 4 Table 4, Levesque et al. 2005
  7. 1 2 Mauron, N.; Josselin, E. (2011). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy and Astrophysics. 526: A156. arXiv:1010.5369Freely accessible. Bibcode:2011A&A...526A.156M. doi:10.1051/0004-6361/201013993.
  8. 1 2 Kholopov, P. N.; Samus', N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (1981). "66th Name-List of Variable Stars". Information Bulletin on Variable Stars. 2042: 1. Bibcode:1981IBVS.2042....1K.
  9. ↑ Lee, O. J.; Baldwin, R. J.; Hamlin, D. W.; Bartlett, T. J.; Gore, G. D.; Baldwin, T. J. (1943). "Dearborn catalog of faint red stars : Titanium oxide stars in zones -4. 5[degrees] to +13.5[degrees]". Annals of the Dearborn Observatory of Northwestern University. 5. Bibcode:1947AnDea...5....1L.
  10. ↑ Nassau, J. J.; Blanco, V. M.; Morgan, W. W. (1954). "Reddened Early m- and S-Type Stars Near the Galactic Equator". Astrophysical Journal. 120: 478. Bibcode:1954ApJ...120..478N. doi:10.1086/145936.
  11. ↑ 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.
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