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28 Aquarii
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	22h 01m 05.01544s
Declination	+00° 36′ 16.9787″
Apparent magnitude (V)	5.597
Characteristics
Spectral type	K2III
U−B color index	+1.40
B−V color index	+1.28
Astrometry
Radial velocity (Rv)	+8.12±0.1 km/s
Proper motion (μ)	RA: +6.22 mas/yr ; Dec.: −11.05 mas/yr
Parallax (π)	5.7956 ± 0.1557 mas
Distance	560 ± 20 ly ; (173 ± 5 pc)
Details
Mass	1.47 M☉
Radius	28.15+0.61; −0.93 R☉
Luminosity	258±8 L☉
Surface gravity (log g)	2.3 cgs
Temperature	4,361 K
Age	2.9 Gyr
Other designations
	28 Aqr, BD−00° 4296, HD 209128, HIP 108691, HR 8390, SAO 127235
Database references
SIMBAD	data

28 Aquarii is a single^[9] star located about 560 light years away from the Sun in the zodiac constellation of Aquarius. 28 Aquarii is the Flamsteed designation.^[8] It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.6.^[2] This object is moving further from the Earth with a heliocentric radial velocity of +8.1 km/s.^[5]

This 2.9^[7] billion year old object is an aging giant star with a stellar classification of K2 III.^[3] After exhausting the hydrogen at its core, this star evolved off the main sequence and has now expanded to 28^[1] times the Sun's radius. It has 1.47 times the mass of the Sun and is radiating 258^[1] times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,361 K.^[7]

References

^ ^a ^b ^c ^d ^e ^f ^g 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. Gaia DR2 record for this source at VizieR.
^ ^a ^b Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
^ ^a ^b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
^ ^a ^b Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
^ ^a ^b Nidever, David L.; Marcy, Geoffrey W.; Butler, R. Paul; Fischer, Debra A.; Vogt, Steven S. (2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–522. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570. S2CID 51814894.
^ ^a ^b van Leeuwen, F.; et al. (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. S2CID 18759600.
^ ^a ^b ^c Martig, Marie; Fouesneau, Morgan; Rix, Hans-Walter; Ness, Melissa; Mészáros, Szabolcs; García-Hernández, D. A.; Pinsonneault, Marc; Serenelli, Aldo; Aguirre, Victor Silva; Zamora, Olga (2016). "Red giant masses and ages derived from carbon and nitrogen abundances". Monthly Notices of the Royal Astronomical Society. 456 (4): 3655. arXiv:1511.08203. Bibcode:2016MNRAS.456.3655M. doi:10.1093/mnras/stv2830.
^ ^a ^b "* 28 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 30 January 2018.
^ 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.