31 Pegasi

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31 Pegasi
Pegasus constellation map.svg
Red circle.svg

Location of 31 Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension 22h 21m 31.07511s[1]
Declination 12° 12′ 18.6628″[1]
Apparent magnitude (V) 4.99[2]
Spectral type B2IV-Ve[3]
U−B color index -0.81[2]
B−V color index -0.10[2]
Variable type γ Cas[4]
Radial velocity (Rv) -5.30[5] km/s
Proper motion (μ) RA: +6.32[1] mas/yr
Dec.: +4.80[1] mas/yr
Parallax (π) 2.01 ± 0.28[1] mas
Distance approx. 1,600 ly
(approx. 500 pc)
Absolute magnitude (MV) -3.61[6]
Mass 11.9[7] M
Luminosity 5582[6] L
Surface gravity (log g) 3.71[8] cgs
Temperature 23,890[8] K
Rotational velocity (v sin i) 98[8] km/s
Other designations
BD+11°4784, FK5 843, GC 31255, HIP 110386, HR 8520, HD 212076, SAO 107854, IN Peg
Database references

31 Pegasi (31 Peg) is a class B2IV-V[3] (blue subgiant) star in the constellation Pegasus. Its apparent magnitude is 4.99[2] and it is approximately 1600 light years away based on parallax.[1]

It is a γ Cas variable, a type of shell star with a circumstellar disc of gas surrounding the star at the equator, ranging from 5.05 to 4.85 magnitude.[4]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ 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. 
  3. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H. 
  4. ^ a b 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....1.2025S. 
  5. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  6. ^ a b Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971Freely accessible. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015.  Vizier catalog entry
  7. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410: 190. arXiv:1007.4883Freely accessible. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x.  Vizier catalog entry
  8. ^ a b c Zorec, J.; Frémat, Y.; Domiciano De Souza, A.; Royer, F.; Cidale, L.; Hubert, A.-M.; Semaan, T.; Martayan, C.; Cochetti, Y. R.; Arias, M. L.; Aidelman, Y.; Stee, P. (2016). "Critical study of the distribution of rotational velocities of Be stars". Astronomy & Astrophysics. 595: A132. Bibcode:2016A&A...595A.132Z. doi:10.1051/0004-6361/201628760.