30 Aquarii

30 Aquarii is a single[10] star located about 301 light years away from the Sun in the zodiac constellation of Aquarius. 30 Aquarii is its Flamsteed designation. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.56.[2] The star is moving further from the Earth with a heliocentric radial velocity of 40 km/s.[2]

30 Aquarii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aquarius
Right ascension  22h 03m 16.45803s[1]
Declination −06° 31′ 20.6748″[1]
Apparent magnitude (V) 5.558[2]
Characteristics
Evolutionary stage giant
Spectral type K1 IV[3] or G8 III[4]
B−V color index 0.951[2]
Variable type Constant[5]
Astrometry
Radial velocity (Rv)39.74[2] km/s
Proper motion (μ) RA: +45.635[1] mas/yr
Dec.: +8.681[1] mas/yr
Parallax (π)10.8432 ± 0.3325[1] mas
Distance301 ± 9 ly
(92 ± 3 pc)
Absolute magnitude (MV)0.88[6]
Details
Mass2.01[2] M☉
Radius9.86+0.23
−0.25[1] R☉
Luminosity54.7±1.9[1] L☉
Surface gravity (log g)2.860[7] cgs
Temperature4,944±79[2] K
Metallicity [Fe/H]−0.11[7] dex
Rotational velocity (v sin i)1.6[8] km/s
Age1.98[2] Gyr
Other designations
30 Aqr, BD−07°5688, HD 209396, HIP 108868, HR 8401, SAO 145836[9]
Database references
SIMBADdata

This object is an aging G-type giant star[6][5] with a stellar classification of G8 III,[4] although Houk and Swift (1999) found a class of K1 IV.[3] It is a red clump giant,[6] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is nearly two[2] billion years old with a leisurely rotation rate, showing a projected rotational velocity of 1.6 km/s.[8] It has double[2] the mass of the Sun and has expanded to ten[1] times the Sun's radius. The star is radiating 55[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,944 K.[2]

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. Gaia DR2 record for this source at VizieR.
  2. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  3. Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
  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.
  5. Henry, Gregory W.; et al. (September 2000), "Photometric Variability in a Sample of 187 G and K Giants", The Astrophysical Journal Supplement Series, 130 (1): 201–225, Bibcode:2000ApJS..130..201H, CiteSeerX 10.1.1.40.8526, doi:10.1086/317346.
  6. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278.
  7. 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, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
  8. Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
  9. "30 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-16.
  10. 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.
  • "30 Aquarii". Star Date Pages. Alcyone Astronomical Software. Retrieved 2008-06-22.
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