38 Aquarii

From Wikipedia, the free encyclopedia
Jump to: navigation, search
38 Aquarii
Diagram showing star positions and boundaries of the Aquarius constellation and its surroundings
Cercle rouge 100%.svg

Location of 38 Aquarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aquarius
Right ascension 22h 10m 37.48206s[1]
Declination –11° 33′ 53.7754″[1]
Apparent magnitude (V) +5.43[2]
Spectral type B5 III[3]
B−V color index –0.12[4]
Radial velocity (Rv) +1.5[2] km/s
Proper motion (μ) RA: +29.29[1] mas/yr
Dec.: +8.76[1] mas/yr
Parallax (π) 7.25 ± 0.33[1] mas
Distance 450 ± 20 ly
(138 ± 6 pc)
Radius 5.6[5] R
Surface gravity (log g) 4.00[3] cgs
Temperature 13,860[3] K
Metallicity [Fe/H] –0.26[3] dex
Rotational velocity (v sin i) 20[6] km/s
Other designations
BD–12° 6196, FK5 3771, HD 210424, HIP 109472, HR 8452, SAO 164910.[7]
Database references

38 Aquarii (abbreviated 38 Aqr) is a star in the equatorial constellation of Aquarius. 38 Aquarii is its Flamsteed designation though it also bears the Bayer designation of e Aquarii. It is a faint star but visible to the naked eye, with an apparent visual magnitude of +5.43.[2] The distance to this star, based upon parallax measurements, is around 450 light-years (140 parsecs).[1]

The spectrum of 38 Aquarii matches a stellar classification of B5 III.[3] A luminosity class of III indicates that this is an evolved giant star. It has 5.6[5] times the radius of the Sun and is spinning with a projected rotational velocity of 20 km/s.[6] The outer atmosphere of the star has a blue-white glow from an effective temperature of 13,860 K.[3]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W. 
  3. ^ a b c d e f Cenarro, A. J.; et al. (January 2007), "Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters", Monthly Notices of the Royal Astronomical Society, 374 (2): 664–690, Bibcode:2007MNRAS.374..664C, arXiv:astro-ph/0611618Freely accessible, doi:10.1111/j.1365-2966.2006.11196.x. 
  4. ^ Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C. 
  5. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, Bibcode:2001A&A...367..521P, arXiv:astro-ph/0012289Freely accessible, doi:10.1051/0004-6361:20000451. 
  6. ^ a b Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590. 
  7. ^ "* e Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2013-05-06.