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31 Pegasi

Location of 31 Pegasi (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Pegasus
Right ascension	22 21 31.07511
Declination	12° 12′ 18.6628″
Apparent magnitude (V)	4.99
Characteristics
Spectral type	B2IV-Ve
U−B color index	-0.81
B−V color index	-0.10
Variable type	γ Cas
Astrometry
Radial velocity (Rv)	−5.30 km/s
Proper motion (μ)	RA: +6.32 mas/yr Dec.: +4.80 mas/yr
Parallax (π)	2.01 ± 0.28 mas
Distance	approx. 1,600 ly (approx. 500 pc)
Absolute magnitude (MV)	−3.61
Details
Mass	12.5±0.7 M☉
Luminosity (bolometric)	27,925+4,360 −3,770 L☉
Surface gravity (log g)	3.71±0.15 cgs
Temperature	23,890±740 K
Rotational velocity (v sin i)	98±8 km/s
Age	15.4±1.3 Myr
Other designations
31 Peg, IN Peg, BD+11°4784, FK5 843, GC 31255, HD 212076, HIP 110386, HR 8520, SAO 107854
Database references
SIMBAD	data

31 Pegasi is a single star in the northern constellation of Pegasus. It is visible to the naked eye as a dim, blue-white hued point of light with a baseline apparent visual magnitude of 4.99. It is located approximately 1,600 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −5.3 km/s.

This is a massive Be star with a stellar classification of B2IV-V. It is a γ Cas variable; a type of shell star with a circumstellar disc of gas surrounding the star at the equator, and ranges from 5.05 up to 4.85 in visual magnitude. It is spinning with a projected rotational velocity of 98 km/s, with the pole being inclined by an estimated angle of 26°±9° to the line of sight from the Earth. The star is 15.4 million years old with 12.5 times the mass of the Sun. It is radiating around 28,000 times the luminosity of the Sun from its photosphere at an effective temperature of 23,890 K.

References

1. ^ 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. S2CID 18759600. Vizier catalog entry
2. ^ 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. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050 (5th Revised ed.). Bibcode:1995yCat.5050....0H.
4. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
5. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
6. ^ Zorec, J.; et al. (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. hdl:11336/37946.
7. ^ Tetzlaff, N.; et al. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873. Vizier catalog entry
8. "31 Peg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-01.
9. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
10. "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
11. Lesh, Janet Rountree (December 1968). "The Kinematics of the Gould Belt: an Expanding Group?". Astrophysical Journal Supplement. 17: 371. Bibcode:1968ApJS...17..371L. doi:10.1086/190179.
12. Samus, N. N.; Durlevich, O. V.; et al. (2009). "General Catalogue of Variable Stars". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.

v t e Constellation of Pegasus
Pegasus in Chinese astronomy List of stars in Pegasus
Stars	Bayer α (Markab) β (Scheat) γ (Algenib) δ (Alpheratz) ε (Enif) ζ (Homam) η (Matar) θ (Biham) ι κ λ μ (Sadalbari) ν ξ ο π π ρ σ τ (Salm) υ (Alkarab) φ χ ψ Flamsteed 1 2 3 4 5 7 9 11 12 13 14 15 16 17 18 19 20 21 23 25 28 30 31 32 33 34 35 36 37 38 39 40 41 45 51 (Helvetios) 52 55 56 57 58 59 60 61 63 64 65 66 67 69 70 71 72 73 74 75 76 77 78 79 80 82 83 85 86 23 Psc 34 Vul Variable S U AG DY EE EQ HN II IK IM LL LO MT V342 V376 V391 HR 8372 8461 HD 219828 220773 Other BD+05 4868 BD+14 4559 (Solaris) Gl 829 Gl 880 HAT-P-8 NGC 8 NGC 18 NGC 30 Q2343-BX418 WASP-10 WASP-21 (Tangra) WASP-52 (Anadolu) WASP-59 WASP-60 (Morava) 3C 454.3
Exoplanets 51 Pegasi b (Dimidium) WASP-10b BD+14 4559 b (Pirx) TOI-5678 b HD 209458 b HR 8799 b c d e
Star clusters	Other Balbinot 1 Messier 15
Nebulae	Other Pease 1
Galaxies	NGC 1 2 9 14 15 16 22 23 26 41 42 52 7033 7034 7042 7043 7053 7056 7066 7068 7074 7085 7190 7217 7236 7237 7303 7312 7315 7317 7318 7319 7320 7320c 7331 7332 7427 7448 7454 7457 7466 7469 7479 7610 7619 7625 7673 7674 7678 7720 7726 7735 7741 7742 NGC 7752 NGC 7753 7767 7769 7773 7800 7814 Other BX442 CTA-102 Einstein Cross Huchra's lens IC 5145 IC 5337 Markarian 335 Pegasus Dwarf Irregular Galaxy Pegasus Dwarf Spheroidal Galaxy Q2343-BX418
Galaxy clusters Abell 2390 NGC 7331 Group Stephan's Quintet
Astronomical events SN 1990U SN 2008ha SN 2013fs
Category

• B-type subgiants
• Be stars
• Gamma Cassiopeiae variable stars
• Pegasus (constellation)
• Durchmusterung objects
• Flamsteed objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects
• Objects with variable star designations