Gamma Aquarii
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 21m 39.37542s[1] |
| Declination | –01° 23′ 14.4031″[1] |
| Apparent magnitude (V) | 3.849[2] |
| Characteristics | |
| Spectral type | A0 V[3] |
| U−B color index | –0.092[2] |
| B−V color index | –0.060[2] |
| Astrometry | |
| Radial velocity (Rv) | –15[4] km/s |
| Proper motion (μ) | RA: +129.53[1] mas/yr Dec.: +7.77[1] mas/yr |
| Parallax (π) | 19.92 ± 1.04[1] mas |
| Distance | 164 ± 9 ly (50 ± 3 pc) |
| Details | |
| Surface gravity (log g) | 4.0[5] cgs |
| Temperature | 10,500[5] K |
| Metallicity [Fe/H] | +0.30[5] dex |
| Rotational velocity (v sin i) | 80[6] km/s |
| Other designations | |
Gamma Aquarii (γ Aqr, γ Aquarii) is the Bayer designation for a star in the constellation Aquarius. It has the traditional name Sadachbia, from an Arabic expression سعد الأخبية sa‘d al-’axbiyah "luck of the homes (tents)". In Hindi it is also called Satabhishaj (a hundred physicians); Sadhayam in Tamil. This star has an apparent visual magnitude of 3.849,[2] making it one of the brighter members of the constellation. Based upon parallax measurements, this star is located at a distance of roughly 164 light-years (50 parsecs) from the Sun, with an error margin of 5%.[1] The star is a spectroscopic binary with a period of 58.1 days.
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Aoul al Achbiya (أول ألأجبية - awwil al ahbiyah), which was translated into Latin as Prima Tabernaculorum, meaning the first of luck of the homes (tents).[8] This star, along with π Aqr (Seat), ζ Aqr (Sadaltager / Achr al Achbiya) and η Aqr (Hydria), were al Aḣbiyah (الأخبية), the Tent.[9][10][11]
In Chinese, 墳墓 (Fén Mù), meaning Tomb, refers to an asterism consisting of γ Aquarii, ζ Aquarii, η Aquarii, π Aquarii.[12] Consequently, γ Aquarii itself is known as 墳墓二 (Fén Mù èr, English: the Second Star of Tomb).[13]
Gamma Aquarii is an A-type main sequence star with a stellar classification of A0 V,[3] making it both larger and more massive than the Sun. It is a candidate Lambda Boötis star, suggesting it may have accreted low-metallicity circumstellar gas some time in the past.[14] It is spinning relatively rapidly with a projected rotational velocity of 80 km s−1.[6] This value gives a lower bound on the actual azimuthal velocity along the star's equator. The outer atmosphere of Gamma Aquarii is radiating energy at an effective temperature of 10,500 K,[5] which is nearly double the temperature at the surface of the Sun. This heat is what gives Gamma Aquarii the white-hot glow of an A-type star.[15]
References
- 1 2 3 4 5 6 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.
- 1 2 3 4 Cousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars 8: 59, Bibcode:1984SAAOC...8...59C.
- 1 2 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.
- ↑ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953QB901.W495......
- 1 2 3 4 Baschek, Bodo; Searle, Leonard (February 1969), "The Chemical Composition of the Lambda Bootis Stars", Astrophysical Journal 155: 537, Bibcode:1969ApJ...155..537B, doi:10.1086/149890.
- 1 2 Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
- ↑ "gam Aqr -- Star in double system", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg).
- ↑ Knobel, E. B. (June 1895), "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket", Monthly Notices of the Royal Astronomical Society 55: 429–438, Bibcode:1895MNRAS..55..429K, doi:10.1093/mnras/55.8.429.
- ↑ 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
- ↑ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York: Dover Publications Inc, p. 52, ISBN 0-486-21079-0, retrieved 2010-12-12.
- ↑ γ Aqr as Aoul al Achbiya or Prima Tabernaculorum (the first of luck of the homes or tents), π Aqr as Wasat al Achbiya or Media Tabernaculorum (the middle of luck of the homes or tents) and ζ Aqr as Achr al Achbiya or Postrema Tabernaculorum (the end of luck of the homes or tents). η Aqr should be designated as al Achbiya consistently, but it was not designated as the Arabic name except the name Hydria (Greek) or Deli (Hebrew)
- ↑ (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.
- ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ King, J. R. (July 1994), "Accretion from Circumstellar Discs and the Lambda-Bootis Phenomenon", Monthly Notices of the Royal Astronomical Society 269 (1): 209–217, Bibcode:1994MNRAS.269..209K, doi:10.1093/mnras/269.1.209.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16.
External links
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