20 Aquarii - Misplaced Pages

Star in the constellation Aquarius

20 Aquarii
Observation data Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	21 24 51.67515
Declination	−03° 23′ 54.0858″
Apparent magnitude (V)	6.38
Characteristics
Spectral type	F0 V or F0 III
B−V color index	0.334±0.002
Astrometry

Radial velocity (R_v)	−23.2±2.9 km/s
Proper motion (μ)	RA: −6.125 mas/yr Dec.: −49.515 mas/yr
Parallax (π)	15.3426 ± 0.0730 mas
Distance	213 ± 1 ly (65.2 ± 0.3 pc)
Absolute magnitude (M_V)	2.37

Details

Mass	1.52 `M`_☉
Luminosity	9.38 `L`_☉
Surface gravity (log g)	4.17 cgs
Temperature	7,314±249 K
Rotational velocity (v sin i)	92 km/s
Age	761 Myr

Other designations
BD−05° 5444, GC 29976, HD 203843, HIP 105729, HR 8192, SAO 145376
Database references
SIMBAD	data

20 Aquarii, abbreviated 20 Aqr, is a star in the constellation Aquarius. 20 Aquarii is the Flamsteed designation. It is a dim star with an apparent visual magnitude of 6.38. Based upon an annual parallax shift of 15.34 mas, it is located 213 light years away but is moving closer to the Earth with a heliocentric radial velocity of −23 km/s. The star is predicted to come to within 110 light-years in around 1.9 million years.

This is an F-type main-sequence star with a stellar classification of F0 V. (Cowley and Fraquelli had given it a class of F0 III.) It is a suspected chemically peculiar Am star showing metallic lines. It is 761 million years old with a high projected rotational velocity of 92 km/s. The star has 1.52 times the mass of the Sun and is radiating 9 times the Sun's luminosity from its photosphere at an effective temperature of about 7,314 K.

References

^ 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.
^ 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.
^ Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
^ Cowley, A.; Fraquelli, D. (1974), "MK Spectral Types for Some Bright F Stars", Publications of the Astronomical Society of the Pacific, 86 (509): 70, Bibcode:1974PASP...86...70C, doi:10.1086/129562.
^ Gontcharov, G. A. (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.
^ David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
^ Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897−911, arXiv:1201.2052, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943, S2CID 14070763.
"20 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 23, 2018.
Renson, P.; Manfroid, J. (2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
Paunzen, E.; et al. (February 2013), "A photometric study of chemically peculiar stars with the STEREO satellites - II. Non-magnetic chemically peculiar stars", Monthly Notices of the Royal Astronomical Society, 429 (1): 119–125, arXiv:1211.1535, Bibcode:2013MNRAS.429..119P, doi:10.1093/mnras/sts318.

Constellation of Aquarius

Stars

Bayer	α (Sadalmelik) β (Sadalsuud) γ (Sadachbia) δ (Skat) ε (Albali) ζ η θ (Ancha) ι κ (Situla) λ (Hydor) μ ν ξ (Bunda) ο π ρ σ τ τ υ φ χ ψ (91) ψ ψ ω ω A A b b b c c c d e f g g h i i i k α PsA C
Flamsteed	1 4 5 7 8 9 10 11 12 14 15 16 17 18 19 20 21 24 26 28 29 30 32 35 36 37 39 40 41 42 44 45 47 49 50 51 54 56 58 60 61 64 65 67 70 72 74 75 77 78 81 82 84 85 87 94 96 97 100
Variable	R U AE DV EP EW EZ FO HK IL HU IZ LL LP
HR	8017 8056 8121 8263 8363 8453 8500 8507 8581 8612 8629 8645 8716 8783 8836 8856 8879 8924 9014
HD	206610 (Bosona) 210277 212771 (Lionrock) 215152 219617 220466 220689 222093 222582
Other	2MASS J21392676+0220226 BD−22 5866 Gliese 849 K2-21 K2-28 K2-58 K2-72 K2-138 LS IV-14 116 Sneden's Star TRAPPIST-1 WASP-6 (Márohu) WASP-47 WASP-69 WASP-75

Exoplanets	ψ Aquarii b Gliese 849 b Gliese 876 b c d e HD 206610 b HD 210277 b HD 212771 b (Victoriapeak) HD 221416 b HD 222582 b K2-66b K2-72b c d e K2-138b TRAPPIST-1b c d e f g h WASP-6b

Star clusters	Messier 2 Messier 72 Messier 73

Nebulae	Helix Nebula Saturn Nebula

Galaxies

NGC	6975 7001 7010 7047 7051 7065 7069 7077 7081 7184 7222 7252 7257 7301 7302 7393 7492 7585 7592 7600 7606 7723 7727 7759
Other	Aquarius Dwarf ESO 603-G21 Lyman-alpha blob 1 PGC 1228197 PHL 293B SMM J2135-0102 WISE J224607.57−052635.0 J2345-0449

Galaxy clusters	Abell 2597 RXC J2211.7-0350 XMMXCS 2215-1738

Astronomical events	SN 2213-1745