Article · Wikipedia archive · Last revised Jun 19, 2026

Beta Equulei

Beta Equulei, Latinized from β Equulei, is the Bayer designation for a solitary star in the northern constellation of Equuleus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.16. The annual parallax shift is 11.27 mas, indicating a separation of around 289 light years from the Sun. It is drifting closer with a radial velocity of −11 km/s.

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Jun 19, 2026
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Beta Equulei
Location of β Equulei (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Equuleus
Right ascension 21h 22m 53.61365s1
Declination +06° 48′ 40.1125″1
Apparent magnitude (V) 5.162
Characteristics
Evolutionary stage Main sequence3
Spectral type A3 V4
U−B color index +0.105
B−V color index +0.064±0.0032
Astrometry
Radial velocity (Rv)−11.1±0.86 km/s
Proper motion (μ) RA: +53.6851 mas/yr
Dec.: +10.1361 mas/yr
Parallax (π)11.2696±0.2608 mas1
Distance289 ± 7 ly
(89 ± 2 pc)
Absolute magnitude (MV)+0.132
Details
Mass2.74±0.043 M☉
Radius4.027 R☉
Luminosity78.32 L☉
Temperature9,0007 K
Rotational velocity (v sin i)58.0±0.74 km/s
Age6007 Myr
Other designations
β Equ, 10 Equulei, BD+06°4811, HD 203562, HIP 105570, HR 8178, SAO 126749, WDS 21229+0649A8
Database references
SIMBADdata

Beta Equulei, Latinized from β Equulei, is the Bayer designation for a solitary9 star in the northern constellation of Equuleus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.16.2 The annual parallax shift is 11.27 mas,1 indicating a separation of around 289 light years from the Sun. It is drifting closer with a radial velocity of −11 km/s.6

This is an ordinary A-type main sequence star with a stellar classification of A3 V.4 It has 2.7 times the mass of the Sun3 and about four7 times the Sun's radius. The star is around 6007 million years old – 93%3 of the way through its main sequence lifetime – and is spinning with a projected rotational velocity of 58 km/s.4 It is radiating 782 times the luminosity of the Sun from its photosphere at an effective temperature of about 9,000 K.7 The star emits an infrared excess indicating the presence of a dusty debris disk. The mean temperature of the dust is 85 K, indicating the semimajor axis of its orbit is 104 AU.7

β Equulei has four optical companions. They are not physically associated with the star described above.10

References

References

  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
  4. Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386, S2CID 119286673.
  5. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  6. Gontcharov, G. A. (November 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.
  7. Rhee, Joseph H.; et al. (May 2007), "Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs", The Astrophysical Journal, 660 (2): 1556–1571, arXiv:astro-ph/0609555, Bibcode:2007ApJ...660.1556R, doi:10.1086/509912, S2CID 11879505.
  8. "bet Equ". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-17.{{cite web}}: CS1 maint: postscript (link)
  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. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
External links
  • Kaler, James B. (December 18, 2009), "Beta Equulei", Stars, University of Illinois.