S Vulpeculae

S Vulpeculae

Observation data Epoch J2000      Equinox J2000
Constellation	Vulpecula
Right ascension	19^h 48^m 23.8067^s[1]
Declination	27° 17′ 11.388″[1]
Apparent magnitude (V)	8.974[2] (8.69 - 9.42[3])
Characteristics
Spectral type	G0-K2(M1)[4]
U−B color index	++1.3 - +2.0[5]
B−V color index	+1.7 - +2.1[5]
Variable type	δ Cep[3]
Astrometry
Radial velocity (Rv)	0.0 ± 2[6] km/s
Proper motion (μ)	RA: −4.4 ± 1.2[7] mas/yr Dec.: −5.1 ± 1.1[7] mas/yr
Distance	3,480[2] pc
Absolute magnitude (MV)	−6.08[2]
Details^[2]
Mass	14.2 M☉
Radius	382[8] R☉
Luminosity	28,840 L☉
Temperature	4,477 K
Metallicity [Fe/H]	−0.01[9] dex
Age	12.6 Myr
Other designations
S Vulpeculae, SAO 87743, HD 338867, BD+26°3674, AAVSO 1944+27
Database references
SIMBAD	data

S Vulpeculae is a supergiant^[10] star in the constellation Vulpecula.

S Vulpeculae was first suspected of varying in brightness in 1836 and this was confirmed by 1862. It has been variously classified as an RV Tauri variable, a semiregular variable star, or a Cepheid variable.^[11][4]

S Vulpeculae is now confirmed as a classical Cepheid variable with one of the longest known periods at 68 days,^[2] although the period has changed several times.^[12] As such, it is also one of the cooler and more luminous of the Cepheids, and it lies close to the zone where semiregular variable stars are found. The shape and amplitude of the light curve varies significantly from cycle to cycle and secularly. The apparent magnitude ranges from 8.69 to 9.42.^[3] The spectrum varies from early G to late K as it pulsates, with TiO bands typical of an M1 star when the star is coolest.^[4]

References

1. Hog, E.; Kuzmin, A.; Bastian, U.; Fabricius, C.; Kuimov, K.; Lindegren, L.; Makarov, V. V.; Roeser, S. (1998). "The TYCHO Reference Catalogue". Astronomy and Astrophysics 335: L65. Bibcode:1998A&A...335L..65H.
2. Turner, David G. (2014). "Towards a Determination of Definitive Parameters for the Long Period Cepheid S Vulpeculae" 1403: arXiv:1403.1968. arXiv:1403.1968. Bibcode:2014arXiv1403.1968T.
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. Bibcode:2009yCat....102025S.
4. Joy, Alfred H. (1952). "The Semiregular Variable Stars of the RV Tauri and Related Classes". Astrophysical Journal 115: 25. Bibcode:1952ApJ...115...25J. doi:10.1086/145506.
5. Berdnikov, L. N.; Ivanov, G. R. (1986). "On the Type of Variability of S Vul". Information Bulletin on Variable Stars 2856: 1. Bibcode:1986IBVS.2856....1B.
6. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
7. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27. Bibcode:2000A&A...355L..27H.
8. Gieren, Wolfgang P.; Fouque, Pascal; Gomez, Matias (1998). "Cepheid Period‐Radius and Period‐Luminosity Relations and the Distance to the Large Magellanic Cloud". The Astrophysical Journal 496: 17. arXiv:astro-ph/9710161. Bibcode:1998ApJ...496...17G. doi:10.1086/305374.
9. Marsakov, V. A.; Koval', V. V.; Kovtyukh, V. V.; Mishenina, T. V. (2013). "Properties of the population of classical Cepheids in the Galaxy". Astronomy Letters 39 (12): 851. Bibcode:2013AstL...39..851M. doi:10.1134/S1063773713120050.
10. Buscombe, W. (1974). "Supergiants in the Milky Way". Perem. Zvezdy 2: 127. Bibcode:1974PZP.....2..127B.
11. Nassau, J. J.; Ashbrook, J. (1943). "S Vulpeculae". Astronomical Journal 50: 97. Bibcode:1943AJ.....50...97N.
12. Heiser, Arnold M. (1996). "BV Observations of the Long-Period Cepheid S Vulpeculae". Publications of the Astronomical Society of the Pacific 108: 603. Bibcode:1996PASP..108..603H. doi:10.1086/133771.