38 Aquarii

38 Aquarii is a star in the equatorial constellation of Aquarius. 38 Aquarii is its Flamsteed designation; its Bayer designation is e Aquarii. It is a faint star but visible to the naked eye, with an apparent visual magnitude of +5.43.[2] Based on parallax measurements, it is around 450 light-years (140 parsecs) away;[1] it is 0.28 degree south of the ecliptic.

This article is about e Aquarii. It is not to be confused with ε (epsilon) Aquarii.
38 Aquarii
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]
Characteristics
Spectral type B5 III[3]
B−V color index –0.12[4]
Astrometry
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
Distance450 ± 20 ly
(138 ± 6 pc)
Absolute magnitude (MV)−0.26[5]
Details
Radius5.6[6] R☉
Luminosity219.16[5] L☉
Surface gravity (log g)4.00[3] cgs
Temperature13,860[3] K
Metallicity [Fe/H]–0.26[3] dex
Rotational velocity (v sin i)20[7] km/s
Other designations
38 Aqr, BD–12°6196, FK5 3771, HD 210424, HIP 109472, HR 8452, SAO 164910[8]
Database references
SIMBADdata

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[6] times the radius of the Sun and is spinning with a projected rotational velocity of 20 km/s.[7] The outer atmosphere of the star has a blue-white glow from an effective temperature of 13,860 K.[3]

References
  1. van Leeuwen, F. (November 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.
  2. Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions, Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W.
  3. 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, arXiv:astro-ph/0611618, Bibcode:2007MNRAS.374..664C, 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. 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.
  6. 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, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. 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.
  8. "* e Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2013-05-06.
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