Astronomy:21 Aquarii

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Short description: Star in the constellation Aquarius
21 Aquarii
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Aquarius
Right ascension  21h 25m 16.95755s[1]
Declination −03° 33′ 24.2964″[1]
Apparent magnitude (V) 5.48[2]
Characteristics
Spectral type K4III[3]
B−V color index 1.451±0.011[2]
Astrometry
Radial velocity (Rv)−24.5±2[4] km/s
Proper motion (μ) RA: −12.061[1] mas/yr
Dec.: −69.973[1] mas/yr
Parallax (π)7.8747 ± 0.2182[1] mas
Distance410 ± 10 ly
(127 ± 4 pc)
Absolute magnitude (MV)0.11[2]
Details
Radius28.01+1.09
−2.12
[1] R
Luminosity203.4±6.4[1] L
Surface gravity (log g)1.79[5] cgs
Temperature4119+165
−78
[1] K
Metallicity [Fe/H]−0.08[5] dex
Other designations
Database references
SIMBADdata

21 Aquarii is a single[6] star in the zodiac constellation of Aquarius. 21 Aquarii is the Flamsteed designation. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.49.[2] This object is a member of the HR 1614 moving group,[7] and is moving closer to the Earth with a heliocentric radial velocity of −24.5 km/s.[4]

This object is an evolved giant star with a stellar classification of K4 III.[3] As a result of having exhausted the hydrogen at its core, it has expanded to 27[1] times the radius of the Sun. The star is radiating 203[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,120 K.[1]

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode2012AstL...38..331A .
  3. 3.0 3.1 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey 5. Bibcode1999MSS...C05....0H. 
  4. 4.0 4.1 Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode1953GCRV..C......0W. 
  5. 5.0 5.1 McWilliam, Andrew (December 1990). "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances". Astrophysical Journal Supplement Series 74: 1075–1128. doi:10.1086/191527. Bibcode1990ApJS...74.1075M. 
  6. Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode2008MNRAS.389..869E. 
  7. Eggen, Olin J.; Iben, Icko Jr. (April 1991), "First giant branch and asymptotic giant branch stars in nearby aggregates", Astronomical Journal 101: 1377–1407, doi:10.1086/115773, Bibcode1991AJ....101.1377E .