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Gamma Aquarii

From Wikipedia, the free encyclopedia
Star in the constellation Aquarius
Gamma Aquarii
Location of γ Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
ConstellationAquarius
Right ascension22h 21m 39.37542s[1]
Declination–01° 23′ 14.4031″[1]
Apparent magnitude (V)3.849[2]
Characteristics
Spectral typeA0 V[3]
U−Bcolor index–0.092[2]
B−Vcolor index–0.060[2]
Astrometry
Radial velocity (Rv)−15.7±0.9[4] km/s
Proper motion (μ)RA: +129.53[1]mas/yr
Dec.: +7.77[1]mas/yr
Parallax (π)19.92±1.04 mas[1]
Distance164 ± 9 ly
(50 ± 3 pc)
Absolute magnitude (MV)+0.10[5]
Details
Aa
Mass2.72±0.04[6] M
Radius2.7[6] R
Surface gravity (log g)3.99±0.14[7] cgs
Temperature10,637±362[7] K
Metallicity [Fe/H]+0.30[8] dex
Rotational velocity (v sin i)80[9] km/s
Age280±20[6] Myr
Ab
Mass0.56[6] M
Radius0.5[6] R
Temperature3,900[6] K
Other designations
Sadalachbia, Sadachbia,Gamma Aqr, γ Aqr,48 Aquarii,BD−02°5741,FK5 842,HD 212061,HIP 110395,HR 8518,SAO 146044,ADS 15864,WDS J22217-0123A[10]
Database references
SIMBADdata

Gamma Aquarii, orγ Aquarii, is abinary star system[6] in theconstellation ofAquarius. It has anapparent visual magnitude of 3.849,[2] making it one of thebrighter members of the constellation. Based uponparallax measurements taken during theHipparcos mission, this star is located at a distance of approximately 164light-years (50parsecs) from theSun.[1] It is drifting closer to the Sun with aradial velocity of −16 km/s.[4] In 1998,Olin J. Eggen included this star as a candidate member of theHyades Supercluster.[5]

The two components are designated Gamma Aquarii Aa, formally calledSadachbia/səˈdækbiə/,[11] and Ab.

Nomenclature

[edit]

γ Aquarii,Latinised toGamma Aquarii, is the system'sBayer designation. WDS J22217-0123 A is its designation in theWashington Double Star Catalog.

It bore the traditional nameSadachbia, from anArabic expression سعد الأخبية (sa‘d al-’axbiyah), meaning "luck of the homes (tents)". InHindi it is also calledSatabhishaj (a hundred physicians); it is calledSadhayam inTamil. In the catalogue of stars in theCalendarium of Al Achsasi Al Mouakket, this star was designatedAoul al Achbiya (أول ألأجبية -awwil al ahbiyah), which was translated intoLatin asPrima Tabernaculorum, meaningthe first of luck of the homes (tents).[12] In 2016, theInternational Astronomical Union organized aWorking Group on Star Names (WGSN)[13] to catalogue and standardize proper names for stars. The WGSN approved the nameSadachbia for the component WDS J22217-0123 Aa on 21 August 2016, and it is now so included in the List of IAU-approved Star Names.[11]

This star, along withPi Aquarii (Seat),Zeta Aquarii (Sadaltager / Achr al Achbiya) andEta Aquarii (Hydria), wereal Aḣbiyah الأخبية "the Tent".[14][15][16]

InChinese,墳墓 (Fén Mù), meaningTomb, refers to anasterism consisting of Gamma Aquarii,Zeta Aquarii,Eta Aquarii andPi Aquarii.[17] Consequently, theChinese name for Gamma Aquarii itself is墳墓二 (Fén Mù èr, English:the Second Star of Tomb).[18]

Properties

[edit]

In 1978 through 1984,H. A. McAlister listed this as aspectroscopic binary star system that is unresolved byspeckle interferometry,[19][20] and it is listed as such in the 1991 revision of theBright Star Catalogue.[21] In 2008,P. P. Eggleton andA. A. Tokovinin listed it as a single star in their catalogue of multiplicity.[22] In 2024, the direct observation of a companion star to Gamma Aquarii was detected byinterferometric observations.[6]

The primary is anA-type main sequence star with astellar classification of A0 V,[3] around 2.7 timeslarger and more massivethan the Sun.[6] It was a candidateLambda Boötis star, suggesting it may have accreted low-metallicity circumstellar gas some time in the past.[23] But it has since been excluded.[24] The star is spinning relatively rapidly with aprojected rotational velocity of80 km s−1.[9] This value gives a lower bound on the actualazimuthal velocity along the star's equator. Theouter atmosphere of Gamma Aquarii is radiating energy at aneffective temperature of 10,500 K,[8] which is nearly double the temperature at the surface of the Sun. This heat is what gives Gamma Aquarii the white-hot glow of anA-type star.[25]

The secondary component is a low-mass star detected viainterferometry in 2024. It has around 0.56 times the mass and half the radius of the Sun. Itseffective temperature of 3,900 K[6] gives it the orange hue typical oflateK-type stars.[25] Located 1.9astronomical units from each other, both stars take around a year to orbit the system'scenter of mass.[6]

References

[edit]
  1. ^abcdefvan 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. ^abcdCousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards",South African Astronomical Observatory Circulars,8: 59,Bibcode:1984SAAOC...8...59C.
  3. ^abCowley, 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. ^abGontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system",Astronomy Letters,32 (11):759–771,arXiv:1606.08053,Bibcode:2006AstL...32..759G,doi:10.1134/S1063773706110065,S2CID 119231169.
  5. ^abEggen, Olin J. (July 1998), "The Age Range of Hyades Stars",The Astronomical Journal,116 (1):284–292,Bibcode:1998AJ....116..284E,doi:10.1086/300413.
  6. ^abcdefghijkWaisberg, Idel; Klein, Ygal; Katz, Boaz (2024-08-01)."Hidden Companions to Intermediate-mass Stars. XXI. Discovery of a 0.5M, 1.5 au Companion to Sadachbia = Gamma Aquarii".Research Notes of the American Astronomical Society.8 (8): 197.Bibcode:2024RNAAS...8..197W.doi:10.3847/2515-5172/ad6b26.ISSN 2515-5172.
  7. ^abDavid, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets",The Astrophysical Journal,804 (2): 146,arXiv:1501.03154,Bibcode:2015ApJ...804..146D,doi:10.1088/0004-637X/804/2/146,S2CID 33401607.Vizier catalog entry
  8. ^abBaschek, 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.
  9. ^abRoyer, 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,S2CID 18475298.
  10. ^"gam Aqr".SIMBAD.Centre de données astronomiques de Strasbourg.{{cite web}}: CS1 maint: postscript (link)
  11. ^ab"Naming Stars". IAU.org. Retrieved26 February 2018.
  12. ^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.
  13. ^IAU Working Group on Star Names (WGSN),International Astronomical Union, retrieved22 May 2016.
  14. ^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
  15. ^Allen, R. H. (1963),Star Names: Their Lore and Meaning (Reprint ed.), New York: Dover Publications Inc, p. 52,ISBN 0-486-21079-0, retrieved2010-12-12.
  16. ^Gamma Aqr asAoul al Achbiya orPrima Tabernaculorum (the first of luck of the homes or tents), Pi Aquarii asWasat al Achbiya orMedia Tabernaculorum (the middle of luck of the homes or tents) and Zeta Aquarii asAchr al Achbiya orPostrema Tabernaculorum (the end of luck of the homes or tents). Eta Aquarii should be designated asal Achbiya consistently, but it was not designated as theArabic name except the nameHydria (Greek) orDeli (Hebrew)
  17. ^(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.
  18. ^(in Chinese)香港太空館 - 研究資源 - 亮星中英對照表Archived August 18, 2010, at theWayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  19. ^McAlister, H. A. (June 1978), "Binary stars unresolved by speckle interferometry",Publications of the Astronomical Society of the Pacific,90:288–296,Bibcode:1978PASP...90..288M,doi:10.1086/130327.
  20. ^Hartkopf, W. I.; McAlister, H. A. (January 1984), "Binary stars unresolved by speckle interferometry. III",Publications of the Astronomical Society of the Pacific,96:105–116,Bibcode:1984PASP...96..105H,doi:10.1086/131309,S2CID 122218502.
  21. ^Hoffleit, Dorrit (1991),The Bright Star Catalogue (5h rev. ed.), Yale University Observatory,Bibcode:1964cbs..book.....H.
  22. ^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.
  23. ^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.
  24. ^Cheng, Kwang-Ping; et al. (January 2017), "Utilizing Synthetic Visible Spectra to Explore the Physical Basis for the Classification of Lambda Boötis Stars",The Astronomical Journal,153 (1): 15,Bibcode:2017AJ....153...39C,doi:10.3847/1538-3881/153/1/39, 39.
  25. ^ab"The Colour of Stars",Australia Telescope, Outreach and Education,Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived fromthe original on 2012-03-18, retrieved2012-01-16.

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