Location of 1 Aqr (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 20 39 24.8927 |
| 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 system in the zodiac constellation of Aquarius, about 263 light years away from the Sun. 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, 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 5.385 yr 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), although rarely used today.
References
- ^ 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.
- ^ Cousins, A. W. J. (1984). "UBV Photometry of Equatorial Stars". South African Astronomical Observatory Circulars. 8: 69–84. Bibcode:1984SAAOC...8...69C.
- ^ 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.
- ^ 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.
- ^ 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, 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.
- ^ 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.
- ^ 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
- ^ 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
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