47 Aquarii

47 Aquarii, abbreviated 47 Aqr, is a star in the zodiac constellation of Aquarius. 47 Aquarii is its Flamsteed designation. It is a faint star but visible to the naked eye in good seeing conditions, having an apparent visual magnitude of 5.135.^[2] Based upon an annual parallax shift of 18.0 mas,^[1] it is located 181 light years away. At that distance, the visual magnitude of the star is diminished by an extinction of 0.088 due to interstellar dust.^[5] It is moving further from the Earth with a heliocentric radial velocity of +48 km/s.^[2]

47 Aquarii

Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
Right ascension	22h 21m 35.56816s[1]
Declination	−21° 35′ 53.6431″[1]
Apparent magnitude (V)	5.135[2]
Characteristics
Spectral type	K0 III[3]
B−V color index	1.054[2]
Astrometry
Radial velocity (Rv)	+48.2[2] km/s
Proper motion (μ)	RA: −10.986[1] mas/yr Dec.: −83.914[1] mas/yr
Parallax (π)	18.0015 ± 0.1709 mas[1]
Distance	181 ± 2 ly (55.6 ± 0.5 pc)
Absolute magnitude (MV)	+1.52[4]
Details[5]
Mass	1.35 M☉
Radius	7.86 R☉
Luminosity	30 L☉
Surface gravity (log g)	2.69 cgs
Temperature	4,750 K
Metallicity [Fe/H]	−0.18±0.08 dex
Rotational velocity (v sin i)	1.43 km/s
Age	2.4[2] Gyr
Other designations
BD−22° 5897, FK5 1584, HD 212010, HIP 110391, HR 8516, SAO 191083[6]
Database references
SIMBAD	data

This is an evolved giant star currently on the red giant branch^[5] with a stellar classification of K0 III.^[3] The star has 1.35 times the mass of the Sun and has expanded to 7.86 times the Sun's radius. It is radiating 30 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,750 K.^[5]

References

1. 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.
2. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
3. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
4. 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.
5. Jones, M. I.; et al. (December 2011), "Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets. I. Sample definition and physical properties", Astronomy & Astrophysics, 536: 7, arXiv:1110.6459, Bibcode:2011A&A...536A..71J, doi:10.1051/0004-6361/201117887, S2CID 55769003, A71.
6. "47 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 23, 2018.