Mu Aquarii

Mu Aquarii, Latinized from μ Aquarii, is the Bayer designation for a binary star[10] system in the equatorial constellation of Aquarius. It is visible to the naked eye with a combined apparent visual magnitude of 4.7.[2] Based upon parallax measurements, the distance to this system is about 157 light-years (48 parsecs).[1] It is drifting closer to the Sun with a radial velocity of −9.1 km/s.[4]

Mu Aquarii
Location of μ Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 20h 52m 39.23277s[1]
Declination −08° 58′ 59.9499″[1]
Apparent magnitude (V) 4.731[2]
Characteristics
Spectral type A3m[3]
U−B color index +0.149[2]
B−V color index +0.322[2]
Astrometry
Radial velocity (Rv)−9.1[4] km/s
Proper motion (μ) RA: +45.75[1] mas/yr
Dec.: -33.59[1] mas/yr
Parallax (π)20.74 ± 0.29 mas[1]
Distance157 ± 2 ly
(48.2 ± 0.7 pc)
Absolute magnitude (MV)+1.31[5]
Orbit[6]
Period (P)1,566±3 d
Semi-major axis (a)≥ 67.06 Gm (0.4483 AU)
Eccentricity (e)0.23±0.19
Periastron epoch (T)2,410,497±52 JD
Semi-amplitude (K1)
(primary)		3.2±0.6 km/s
Details
A
Radius3.54+0.45
−0.15[7] R☉
Luminosity25.6±1.4[8] L☉
Surface gravity (log g)3.99[8] cgs
Temperature6,906+151
−405[8] K
Rotational velocity (v sin i)53.7[8] km/s
Other designations
μ Aqr, 6Aquarii, BD−09 5598, FK5 1547, HD 198743, HIP 103045, HR 7990, SAO 144895, WDS 20527-0859A[9]
Database references
SIMBADdata

This star was tentatively identified as a single-lined spectroscopic binary by Helmut A. Abt in 1961.[11] It has an orbital period of 4.29 yr and an eccentricity (ovalness) of 0.23.[6] The pair have been resolved by speckle interferometry, showing an angular separation of 0.06″.[12] The visible spectrum matches a stellar classification of A3m, with the 'm' suffix indicating that this is an Am, or chemically peculiar star.[3] The primary has an estimated 3.5 times the Sun's radius and is radiating 26 times the luminosity of the Sun from its photosphere at an effective temperature of 6,906 km/s.[7]

This star together with ν Aquarii is Albulaan /ˌælbjəˈlɑːn/, derived from an Arabic term al-bulaʽān (ألبولعان) meaning "the two swallowers". This star, along with ε Aqr (Albali) and ν Aqr (Albulaan), were al Bulaʽ (البلع), the Swallower.[13][14] In Chinese, 女宿 (Nǚ Xiù), meaning Girl (asterism) (or Woman), refers to an asterism consisting of μ Aquarii, ε Aquarii, 4 Aquarii, 5 Aquarii and 3 Aquarii.[15] Consequently, the Chinese name for μ Aquarii itself is 女宿二 (Nǚ Xiù èr, English: the Second Star of Girl / Woman.)[16]

References
  1. van Leeuwen, F. (November 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.
  2. Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, Publicaciones Universidad de Chile, Department de Astronomy, 1: 1–17, Bibcode:1966PDAUC...1....1G.
  3. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. Wilson, Ralph Elmer (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W.
  5. 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.
  6. Abt, H. A.; Levy, S. G. (October 1985), "Improved study of metallic-line binaries", The Astrophysical Journal Supplement Series, 59: 229–247, Bibcode:1985ApJS...59..229A, doi:10.1086/191070.
  7. 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.
  8. Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377
  9. "* 6 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-01.
  10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  11. Abt, Helmut A. (March 1961), "The Frequency of Binaries among Metalmc-Line Stars", The Astrophysical Journal Supplement Series, 6: 37, Bibcode:1961ApJS....6...37A, doi:10.1086/190060.
  12. Hartkopf, William I.; et al. (2000), "ICCD Speckle Observations of Binary Stars. XXIII. Measurements during 1982-1997 from Six Telescopes, with 14 New Orbits", The Astronomical Journal, 119 (6): 3084, Bibcode:2000AJ....119.3084H, doi:10.1086/301402.
  13. Davis Jr., G. A. (October 1944), "The Pronunciations, Derivations, and Meanings of a Selected List of Star Names", Popular Astronomy, 52 (3): 12, Bibcode:1944PA.....52....8D.
  14. Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York: Dover Publications Inc, p. 53, ISBN 0-486-21079-0, retrieved 2010-12-12.
  15. (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  16. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 14 日
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