1 Aquarii

1 Aquarii
	Location of 1 Aqr (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	20h 39m 24.8927s
Declination	+00° 29′ 11.155″
Apparent magnitude (V)	5.151
Characteristics
Evolutionary stage	horizontal branch
Spectral type	K1III
U−B color index	0.936
B−V color index	1.060
Astrometry
Radial velocity (Rv)	−40.93(3) km/s
Proper motion (μ)	RA: 96.805(120) mas/yr ; Dec.: −10.140(94) mas/yr
Parallax (π)	12.3852 ± 0.1134 mas
Distance	263 ± 2 ly ; (80.7 ± 0.7 pc)
Absolute magnitude (MV)	0.77
Orbit
Primary	1 Aquarii A
Companion	1 Aquarii B
Period (P)	1966.7±2.9 days
Eccentricity (e)	0.368±0.009
Periastron epoch (T)	54740±7
Argument of periastron (ω); (secondary)	150.7±1.6°
Semi-amplitude (K1); (primary)	3.24±0.04 km/s
Details
Mass	1.50±0.43 M☉
Radius	11 R☉
Luminosity	53.7 L☉
Surface gravity (log g)	2.63±0.11 cgs
Temperature	4715±15 K
Metallicity	−0.12
Rotational velocity (v sin i)	1.8 km/s
Age	1.26 Gyr
Other designations
	1 Aqr, BD+0°4064, FK5 3651, HD 196758, HIP 101936, HR 7897, SAO 126062, CCDM J20394+0029, WDS J20394+0029
Database references
SIMBAD	data

1 Aquarii is a binary star^[5] system in the zodiac constellation of Aquarius, about 263 light years away from the Sun.^[1] 1 Aquarii is the Flamsteed designation. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.151,^[2] located a degree north of the celestial equator.^[5] The system is moving closer to the Earth with a heliocentric radial velocity of −41 km/s.^[5]

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 5.385 yr and an eccentricity of 0.368.^[5] The visible component is an aging giant star with a stellar classification of K1III.^[4] At the age of 1.26^[7] 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.^[3] The star has 1.5^[7] times the mass of the Sun and has expanded to 11^[8] times the Sun's radius. It is radiating 53.7^[8] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,715 K.^[9]

The mass of the companion appears small, suggesting a red dwarf no higher than class M5.^[5] In addition to the spectroscopic companion there are two faint optical companions that have no physical relation to 1 Aqr.^[11]

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), although rarely used today.^[12]^[13]

References

^ ^a ^b ^c ^d ^e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^a ^b ^c ^d Cousins, A. W. J. (1984). "UBV Photometry of Equatorial Stars". South African Astronomical Observatory Circulars. 8: 69–84. Bibcode:1984SAAOC...8...69C.
^ ^a ^b 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, S2CID 16673121.
^ ^a ^b Roman, Nancy G. (1952). "The Spectra of the Bright Stars of Types F5-K5". Astrophysical Journal. 116: 122–143. Bibcode:1952ApJ...116..122R. doi:10.1086/145598.
^ ^a ^b ^c ^d ^e ^f ^g Griffin, R. F. (2014). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 239: HD 134169, HD 176526, 1 Aquarii, and HD 219420". The Observatory. 134: 316–339. Bibcode:2014Obs...134..316G.
^ ^a ^b ^c Pace, G.; Pasquini, L.; Ortolani, S. (2003). "The Wilson-Bappu effect: A tool to determine stellar distances". Astronomy and Astrophysics. 401 (3): 997–1008. arXiv:astro-ph/0301637. Bibcode:2003A&A...401..997P. doi:10.1051/0004-6361:20030163. S2CID 17029463.
^ ^a ^b ^c ^d ^e Feuillet, Diane K.; Bovy, Jo; Holtzman, Jon; Girardi, Léo; MacDonald, Nick; Majewski, Steven R.; Nidever, David L. (2016). "Determining Ages of APOGEE Giants with Known Distances". The Astrophysical Journal. 817 (1): 40. arXiv:1511.04088. Bibcode:2016ApJ...817...40F. doi:10.3847/0004-637X/817/1/40. S2CID 118675933.
^ ^a ^b ^c ^d 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, S2CID 121883397
^ ^a ^b 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.Vizier catalog entry
^ "11 Per". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-28.
^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
^ A Llnguist's Angle on the Star of Bethlehem — i.e. α Aquarii; Coates, Richard; Astronomy & Geophysics, Volume 49, Issue 5; (01 October 2008); Pp. 5.27–5.32; https://doi.org/10.1111/j.1468-4004.2008.49527.x
^ Star Names; Arecibo Observatory website; mod.: Steve Gibson; accessed March 2019

[Gaia_DR3-1] Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[Cousins1984-2] Cousins, A. W. J. (1984). "UBV Photometry of Equatorial Stars". South African Astronomical Observatory Circulars. 8: 69–84. Bibcode:1984SAAOC...8...69C.

[Alves2000-3] 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, S2CID 16673121.

[Roman1952-4] Roman, Nancy G. (1952). "The Spectra of the Bright Stars of Types F5-K5". Astrophysical Journal. 116: 122–143. Bibcode:1952ApJ...116..122R. doi:10.1086/145598.

[Griffin2014-5] ^ ^a ^b ^c ^d ^e ^f ^g Griffin, R. F. (2014). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 239: HD 134169, HD 176526, 1 Aquarii, and HD 219420". The Observatory. 134: 316–339. Bibcode:2014Obs...134..316G.

[pace-6] Pace, G.; Pasquini, L.; Ortolani, S. (2003). "The Wilson-Bappu effect: A tool to determine stellar distances". Astronomy and Astrophysics. 401 (3): 997–1008. arXiv:astro-ph/0301637. Bibcode:2003A&A...401..997P. doi:10.1051/0004-6361:20030163. S2CID 17029463.

[Feuillet2016-7] Feuillet, Diane K.; Bovy, Jo; Holtzman, Jon; Girardi, Léo; MacDonald, Nick; Majewski, Steven R.; Nidever, David L. (2016). "Determining Ages of APOGEE Giants with Known Distances". The Astrophysical Journal. 817 (1): 40. arXiv:1511.04088. Bibcode:2016ApJ...817...40F. doi:10.3847/0004-637X/817/1/40. S2CID 118675933.

[Massarotti2008-8] 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, S2CID 121883397

[Luck2015-9] 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.Vizier catalog entry

[Simbad-10] "11 Per". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-28.

[WDSC2014-11] Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.

[12] A Llnguist's Angle on the Star of Bethlehem — i.e. α Aquarii; Coates, Richard; Astronomy & Geophysics, Volume 49, Issue 5; (01 October 2008); Pp. 5.27–5.32; https://doi.org/10.1111/j.1468-4004.2008.49527.x

[13] Star Names; Arecibo Observatory website; mod.: Steve Gibson; accessed March 2019

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1 Aquarii

Etymology

References

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