Gamma Equulei

γ Equulei


Location of γ Equulei (circled)

Observation data
Epoch J2000      Equinox J2000
Constellation Equuleus
Right ascension 21h 10m 20.50005s[1]
Declination 10° 07′ 53.6763″[1]
Apparent magnitude (V) 4.69[2]
Characteristics
Spectral type A9 Sr Eu[3]
U−B color index +0.10[2]
B−V color index +0.26[2]
R−I color index +0.10
Variable type roAp[4]
Astrometry
Radial velocity (Rv)-16.5 ± 0.3 km/s
Proper motion (μ) RA: 48.74[1] mas/yr
Dec.:  mas/yr
Parallax (π)27.55 ± 0.62[1] mas
Distance118 ± 3 ly
(36.3 ± 0.8 pc)
Details
Radius2.20 ± 0.12 R☉
Luminosity12.8 ± 1.4 L☉
Surface gravity (log g)4.47[5] cgs
Temperature8,574[5] K
Metallicity [Fe/H]+0.68[5] dex
Other designations
γ Equulei, γ Equ, Gamma Equulei, Gamma Equ, 5 Equulei, 5 Equ, BD +9 4732, FK5 1555, HD 201601, HIP 104521, HR 8097, SAO 126593[4]

Gamma Equulei (γ Equulei, γ Equ) is a double star[6] in the northern constellation of Equuleus. It is located at a distance of around 118 light-years (36 parsecs) from Earth[1] and has an apparent visual magnitude of 4.7.[2]

The primary component is a chemically peculiar star with a stellar classification of A9 Sr Eu[3] and an apparent magnitude of 4.80.[4] Gamma Equulei undergoes periodic pulsations in luminosity, which places it among the category of roAp stars.[7] The surface magnetic field undergoes long term variation with a period of 91.1 ± 3.6 years, ranging from +577 G to –1,101 G.[8] It has a magnitude 9.05 companion at an angular separation of 1.26 arcseconds.[6]

References

  1. 1 2 3 4 5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
  3. 1 2 Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
  4. 1 2 3 "del Ara -- Star in double system", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-27.
  5. 1 2 3 Koleva, M.; Vazdekis, A. (February 2012), "Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library", Astronomy & Astrophysics, 538: A143, arXiv:1111.5449Freely accessible, Bibcode:2012A&A...538A.143K, doi:10.1051/0004-6361/201118065.
  6. 1 2 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  7. ↑ Perraut, K.; et al. (February 2011), "The fundamental parameters of the roAp star γ Equulei", Astronomy and Astrophysics, 526: A89, arXiv:1011.2028Freely accessible, Bibcode:2011A&A...526A..89P, doi:10.1051/0004-6361/201015801.
  8. ↑ Bychkov, V. D.; Bychkova, L. V.; Madej, J. (January 2006), "Secular variability of the longitudinal magnetic field of the Ap star γ Equ", Monthly Notices of the Royal Astronomical Society, 365 (2): 585–589, arXiv:astro-ph/0510529Freely accessible, Bibcode:2006MNRAS.365..585B, doi:10.1111/j.1365-2966.2005.09738.x.

External links

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