1 Aquarii

Binary star in the constellation Aquarius 1 Aquarii Aquarius constellation map.svg center right 280 Red circle.svg 12 1 Aquarii 958 295 Location of 1 Aqr (circled) J2000 Aquarius 20 39 24.8927 +00 29 11.155 5.151 horizontal branch K1III 1.060 0.936 −40.93 (3) 96.805 (120) −10.140 (94) 12.3852 0.1134 0.7710.1051/0004-6361:20030163 free The Wilson-Bappu effect: A tool to determine stellar distances Astronomy and Astrophysics 401 3 997–1008 2003 Pace G. Pasquini L. Ortolani S. 2003A&A...401..997P astro-ph/0301637 17029463 1 Aquarii A 1 Aquarii B 1966.7 2.9 days 0.368 0.009 54740 7 150.7 1.6 3.24 0.04 1.50 0.43 11 53.7 4715 15 −0.12 1.8 2.63 0.11 1.26 1 Aqr −00°4064 3651 196758 101936 7897 126062 J20394+0029 J20394+0029 11 Per 2019-03-28 1+Aqr 1 Aquarii, or WDS J20394+0029, is a binary star system in the zodiac constellation of Aquarius, about 263 light years away from the Sun. 1 Aquarii is its Flamsteed designation. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.151, located a degree north of the celestial equator. The system is moving closer to the Earth with a heliocentric radial velocity of −41 km/s. Systematic observation for determining the orbit of this system began in 2002, some eighty years following the first radial velocity measurements. It is a single-lined spectroscopic binary with an orbital period of 1966.7 days years out and an eccentricity of 0.368. The visible component is an aging giant star with a stellar classification of K1III. At the age of 1.26 billion years old it is a red clump giant, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star has 1.5 times the mass of the Sun and has expanded to 11 times the Sun's radius. It is radiating 53.7 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,715 K. The mass of the companion appears small, suggesting a red dwarf no higher than class M5. In addition to the spectroscopic companion there are two faint optical companions that have no physical relation to 1 Aqr. Etymology 1 Aquarii was known to the ancients as al-sa'd al-malik, or "the lucky star of the king." Interpreting the unexpressed Arabic vowels, al-sa'd al-mulk, gives an alternate translation of "the lucky star of the kingdom." In English, the name is Sadalmelik (or Sadalmelek), now used for the star Alpha Aquarii.Coates Richard A linguist's angle on the Star of Bethlehem Astronomy and Geophysics 2008 49 280 5.27–5.32 10.1111/j.1468-4004.2008.49527.x 2008A&G....49e..27C Star Names https://www.naic.edu/~gibson/starnames/starnames.html dead https://web.archive.org/web/20190326021111/https://www.naic.edu/~gibson/starnames/starnames.html 2019-03-26 2025-10-30 National Astronomy and Ionosphere Center References UBV Photometry of Equatorial Stars Cousins A. W. J. South African Astronomical Observatory Circulars 8 69–84 1984 1984SAAOC...8...69C 4231171058672649856 Spectroscopic binary orbits from photoelectric radial velocities. Paper 239: HD 134169, HD 176526, 1 Aquarii, and HD 219420 Griffin R. F. The Observatory 134 316–339 2014 2014Obs...134..316G free Abundances in the Local Region. I. G and K Giants Luck R. Earle Astronomical Journal 150 3 88 2015 1507.01466 2015AJ....150...88L 10.1088/0004-6256/150/3/88 118505114 Vizier catalog entry The Spectra of the Bright Stars of Types F5-K5 Roman Nancy G. Astrophysical Journal 116 122–143 1952 1952ApJ...116..122R 10.1086/145598 free 2016ApJ...817...40F 10.3847/0004-637X/817/1/40 1511.04088 Determining Ages of APOGEE Giants with Known Distances The Astrophysical Journal 817 1 40 2016 Feuillet Diane K. Bovy Jo Holtzman Jon Girardi Léo MacDonald Nick Majewski Steven R. Nidever David L. 118675933 free 1 Massarotti Alessandro Latham David W. Stefanik Robert P. Fogel Jeffrey Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity The Astronomical Journal 135 1 209–231 January 2008 10.1088/0004-6256/135/1/209 2008AJ....135..209M 121883397 free Alves David R. K-Band Calibration of the Red Clump Luminosity The Astrophysical Journal 539 2 732–741 August 2000 10.1086/309278 2000ApJ...539..732A astro-ph/0003329 16673121 . 1 Mason B. D. Wycoff G. L. Hartkopf W. I. Douglass G. G. Worley C. E. The Washington Visual Double Star Catalog 2014 2001AJ....122.3466M . 10.1086/323920 122 6 The Astronomical Journal 3466–3471 free Category:K1III stars Category:Horizontal-branch stars Category:Spectroscopic binaries Category:Triple stars Category:Aquarius (constellation) BD+00 4064 Aquarii, 001 196758 101936 7897