Theta Aquilae
  | |
| Observation data EpochJ2000EquinoxJ2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 20h11m18.28528s[1] |
| Declination | –00° 49′ 17.2626″[1] |
| Apparent magnitude(V) | 3.26[2] |
| Characteristics | |
| Spectral type | B9.5 III + B9.5 III[3] |
| U−Bcolor index | –0.15[2] |
| B−Vcolor index | –0.07[2] |
| Astrometry | |
| Radial velocity(Rv) | –27.3[4]km/s |
| Proper motion(μ) | RA:+35.26[1]mas/yr Dec.:+5.71[1]mas/yr |
| Parallax(π) | 11.39 ± 0.24mas[1] |
| Distance | 286 ± 6ly (88 ± 2pc) |
| Absolute magnitude(MV) | –1.39/0.14[5] |
| Orbit[6] | |
| Period(P) | 17.124281 ± 0.000038 days |
| Semi-major axis(a) | 3.148 ± 0.002 mas″ |
| Eccentricity(e) | 0.6040 ± 0.0009 |
| Inclination(i) | 144.10 ± 0.18° |
| Longitude of the node(Ω) | 96.92 ± 0.19° |
| Periastronepoch(T) | JD2458624.154 ± 0.004 |
| Argument of periastron(ω) (primary) | 33.73 ± 0.22° |
| Semi-amplitude(K1) (primary) | 48.78 ± 0.09km/s |
| Semi-amplitude(K2) (secondary) | 63.48 ± 0.11km/s |
| Details | |
| θ Aql A | |
| Mass | 3.564 ± 0.049[6]M☉ |
| Radius | 4.76 ± 0.14[6]R☉ |
| Luminosity | 229.8 ± 22.5[6]L☉ |
| Surface gravity(logg) | 3.64 ± 0.02[6]cgs |
| Temperature | 10300 ± 200[6]K |
| Metallicity[Fe/H] | +0.20[7]dex |
| Rotational velocity(vsini) | 36.3 ± 0.4[6]km/s |
| Age | 20.9[5]Myr |
| θ Aql B | |
| Mass | 2.739 ± 0.037[6]M☉ |
| Radius | 2.34 ± 0.07[6]R☉ |
| Luminosity | 54.0 ± 5.8[6]L☉ |
| Surface gravity(logg) | 4.14 ± 0.02[6]cgs |
| Temperature | 10230 ± 220[6]K |
| Rotational velocity(vsini) | 13.6 ± 0.9[6]km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Theta Aquilae(θ Aql, θ Aquilae) is abinary starin theconstellationAquila.The combinedapparent visual magnitudeof the pair is 3.26,[2]making it the fourth-brightest member of the constellation. InChinese,it has the traditional nameTseen Foo/ˌsiːnˈfuː/,from the Chinese thiênPhù(Mandarinpronunciationtiānfú), which could mean "heavenly raft" or "heavenly ridgepole"; it might also mean "heavenly drumsticks", with Altair, Beta Aquilae and Gamma Aquilae being the drum. This distance to this star can be determined through theparallaxtechnique, yielding an estimate of roughly 286light-years(88parsecs) from Earth.[1]
Properties
[edit]Theta Aquilae is a double-linedspectroscopic binary,[8]which indicates that the individual components have not been viewed through a telescope; instead, what can be viewed is their combinedspectrumwith the individualabsorption linefeatures shifting back and forth over the course of an orbit because of theDoppler effect.Their orbit has a period of 17.1 days with a largeorbital eccentricityis 0.60. At the estimated distance of this system, theangular separationof 3.2[5]milliarcsecondscorresponds to a physical separation of only about 0.24–0.28astronomical units.[9]
Both stars have a matchingstellar classificationof B9.5 III,[3]indicating that they are massive, B-typegiant starsthat have exhausted the supply of hydrogen at their cores and evolved away from themain sequenceof stars like theSun.Hummel et al. (1996) gave the primary component, θ Aql A, an estimated mass of 3.6 solar, a radius 4.8 the Sun's, and 278 the luminosity of the Sun. For the secondary component, θ Aql B, they give the corresponding parameters as 2.9 times the mass, 2.4 times the radius and 68 times the luminosity of the Sun.[5]Based upon their estimated parameters, Kaler (2008) suggests that θ Aql A is actually asubgiant star,while θ Aql B is amain sequencestar.[9]
Etymology
[edit]InChinese,Thiên phù(Tiān Fú), meaningCelestial Drumstick,refers to an asterism consisting of θ Aquilae,62 Aquilae,58 Aquilaeandη Aquilae.[10]Consequently, theChinese namefor θ Aquilae itself isThiên phù nhất(Tiān Fú yī,English:the First Star of Celestial Drumstick.)[11]
In the catalogue of stars in theCalendariumofAl Achsasi al Mouakket,this star was designatedThanih Ras al Akab(تاني ألرأس ألعقاب-taanii al ra’s alʕuqāb), which was translated intoLatinasSecunda Capitis Vulturis,meaningthe second (star) of eagle's head.[12]
This star, along withδ Aqlandη Aql,wereAl Mizān(ألميزان), the Scale-beam.[13]According to the catalogue of stars in theTechnical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars,Al Mizānwere the title for three stars:δ AqlasAl Mizān I,η AqlasAl Mizān IIand θ Aql asAl Mizān III.[14]
This star, together with η Aql, δ Aql,ι Aql,κ Aqlandλ Aql,constituted the obsolete constellationAntinous.[15]
References
[edit]- ^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,S2CID18759600.
- ^abcdCowley, 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.
- ^abCunha, M. S.; et al. (November 2007), "Asteroseismology and interferometry",The Astronomy and Astrophysics Review,14(3–4): 217–360,arXiv:0709.4613,Bibcode:2007A&ARv..14..217C,doi:10.1007/s00159-007-0007-0,S2CID16590095.
- ^Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities",Washington,Carnegie Institute of Washington D.C.,Bibcode:1953GCRV..C......0W.
- ^abcdHummel, C. A.; et al. (July 1995), "Orbits of Small Angular Scale Binaries Resolved with the Mark III Interferometer",Astronomical Journal,110:376,Bibcode:1995AJ....110..376H,doi:10.1086/117528.
- ^abcdefghijklmLester, Kathryn V.; Schaefer, Gail H.; Fekel, Francis C.; Gies, Douglas R.; Henry, Todd J.; Jao, Wei-Chun; Paredes, Leonardo A.; Hubbard-James, Hodari-Sadiki; Farrington, Christopher D.; Gordon, Kathryn D.; Chojnowski, S. Drew; Monnier, John D.; Kraus, Stefan; Bouquin, Jean-Baptiste Le; Anugu, Narsireddy; Brummelaar, Theo Ten; Davies, Claire L.; Gardner, Tyler; Labdon, Aaron; Lanthermann, Cyprien; Setterholm, Benjamin R. (2022)."Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692".The Astronomical Journal.164(6): 228.arXiv:2209.09993.Bibcode:2022AJ....164..228L.doi:10.3847/1538-3881/ac9385.S2CID252408703.
- ^Adelman, S. J.; Nasson, M. A. (June 1980), "Abundance analyses of Theta Aquilae /B9.5 III/, Nu Capricorni /B9.5 V/, and Sigma Aquarii /AO IVs/",Publications of the Astronomical Society of the Pacific,92:346–356,Bibcode:1980PASP...92..346A,doi:10.1086/130675.
- ^van Rensbergen, W.; De Loore, C.; Jansen, K. (February 2006), "Evolution of interacting binaries with a B type primary at birth",Astronomy and Astrophysics,446(3): 1071–1079,Bibcode:2006A&A...446.1071V,doi:10.1051/0004-6361:20053543.
- ^abKaler, James B. (September 19, 2008),"THETA AQL (Theta Aquilae)",Stars,University of Illinois,retrieved2012-02-19.
- ^(in Chinese)Trung quốc tinh tọa thần thoại,written by trần cửu kim. Published by đài loan thư phòng xuất bản hữu hạn công tư, 2005,ISBN978-986-7332-25-7.
- ^(in Chinese)AEEA (Activities of Exhibition and Education in Astronomy) thiên văn giáo dục tư tấn võng 2006 niên 7 nguyệt 3 nhật
- ^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(8): 429,Bibcode:1895MNRAS..55..429K,doi:10.1093/mnras/55.8.429.
- ^Allen, R. H.(1963),Star Names: Their Lore and Meaning(Reprint ed.), New York: Dover Publications Inc., p.61,ISBN0-486-21079-0,retrieved2010-12-12.
- ^Rhoads, Jack W. (November 15, 1971),Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars(PDF),Jet Propulsion Laboratory, California Institute of Technology.
- ^Ian Ridpath's Star Tales - Antinous
