SV Vulpeculae

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SV Vulpeculae
Observation data
Epoch J2000      Equinox J2000
Constellation Vulpecula
Right ascension 19h 51m 30.90640s[1]
Declination 27° 27′ 36.8307″[1]
Apparent magnitude (V) 6.72 - 7.79[2]
Spectral type F7Iab-K0Iab[2]
U−B color index +0.868 - +1.659[3]
B−V color index +1.149 - +1.786[3]
Variable type δ Cep[2]
Radial velocity (Rv)−2.00[4] km/s
Proper motion (μ) RA: −1.50[1] mas/yr
Dec.: −6.57[1] mas/yr
Parallax (π)0.180 ± 0.81[1] mas
Distance2,450[5] pc
Absolute magnitude (MV)−6.21[5]
Mass14.6 - 15.8[6] M
Radius187.9 - 238.4[7] R
Diameter187.9 - 238.4[7] D
Luminosity19,800[8] L
Surface gravity (log g)0.50 - 1.60[9] cgs
Temperature4,861 - 6,110[9] K
Other designations
SV Vul, HD 187921, HIP 97717, BD+27°3536
Database references

SV Vulpeculae is a Classical Cepheid (δ Cepheid) variable star in the constellation Vulpecula. It is a supergiant at a distance of 8,000 light years.

SV Vulpeculae is a δ Cepheid variable whose visual apparent magnitude ranges from 6.72 to 7.79 over 45.0121 days. The light curve is highly asymmetric, with the rise from minimum to maximum taking more less than a third of the time for the fall from maximum to minimum.[10] The period has been decreasing on average by 214 seconds/year.[8]

SV Vulpeculae is a yellow bright supergiant around twenty thousand times as luminous as the sun, with a spectral type that varies from late F to early K. It pulsates and varies in temperature from below 5,000 K to above 6,000 K.[9] The radius is 216.5 D at maximum, and varies from 188 D to 238 D as the star pulsates.[7]

The mass of SV Vulpeculae is now near 15 M, and is estimated to have been about 17 M when it was on the main sequence. The rate of change of the period and the atmospheric abundances show that the star is crossing the instability strip for the second time. The first instability strip crossing occurs rapidly during the transition from the main sequence to becoming a red supergiant. The second crossing occurs during core helium burning when the star executes a blue loop, becoming hotter for a time before returning to the red supergiant stage.[8]


  1. 1.0 1.1 1.2 1.3 1.4 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode 2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. 2.0 2.1 2.2 Samus, N. N.Expression error: Unrecognized word "etal". (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.
  3. 3.0 3.1 Berdnikov, L. N. (2008). "VizieR Online Data Catalog: Photoelectric observations of Cepheids in UBV(RI)c (Berdnikov, 2008)". VizieR On-line Data Catalog: II/285. Originally published in: 2008yCat.2285....0B 2285. Bibcode 2008yCat.2285....0B.
  4. 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.
  5. 5.0 5.1 Groenewegen, M. A. T. (2008). "Baade-Wesselink distances and the effect of metallicity in classical cepheids". Astronomy and Astrophysics 488: 25. arXiv:0807.1269. Bibcode 2008A&A...488...25G. doi:10.1051/0004-6361:200809859.
  6. Caputo, F.; Bono, G.; Fiorentino, G.; Marconi, M.; Musella, I. (2005). "Pulsation and Evolutionary Masses of Classical Cepheids. I. Milky Way Variables". The Astrophysical Journal 629 (2): 1021. arXiv:astro-ph/0505149. Bibcode 2005ApJ...629.1021C. doi:10.1086/431641.
  7. 7.0 7.1 Imbert, M. (1999). "Détermination des rayons de Céphéides. V. Vitesses radiales et dimensions de 22 Céphéides galactiques. Determination of the radii of Cepheids V. Radial velocities and dimensions of 22 galactic Cepheids". Astronomy and Astrophysics Supplement 140: 79. Bibcode 1999A&AS..140...79I. doi:10.1051/aas:1999515.
  8. 8.0 8.1 8.2 Turner, D. G.; Berdnikov, L. N. (2004). "On the crossing mode of the long-period Cepheid SV Vulpeculae". Astronomy and Astrophysics 423: 335. Bibcode 2004A&A...423..335T. doi:10.1051/0004-6361:20040163.
  9. 9.0 9.1 9.2 9.3 Kovtyukh, V. V.; Andrievsky, S. M.; Belik, S. I.; Luck, R. E. (2005). "Phase-dependent Variation of the Fundamental Parameters of Cepheids. II. Periods Longer than 10 Days". The Astronomical Journal 129: 433. Bibcode 2005AJ....129..433K. doi:10.1086/426339.
  10. Schaltenbrand, R.; Tammann, G. A. (1971). "The light curve parameters of photoelectrically observed galactic Cepheids". Astronomy and Astrophysics Supplement 4: 265. Bibcode 1971A&AS....4..265S.

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