Iota Apodis

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Iota Apodis
Diagram showing star positions and boundaries of the Apus constellation and its surroundings
Cercle rouge 100%.svg

Location of ι Apodis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Apus
Right ascension 17h 22m 05.87559s[1]
Declination –70° 07′ 23.5400″[1]
Apparent magnitude (V) 5.41[2] (5.90/6.46)[3]
Spectral type B9 V + B9.5 V[3]
U−B color index –0.23[2]
B−V color index –0.04[2]
Radial velocity (Rv) -4.3[4] km/s
Proper motion (μ) RA: –1.94[1] mas/yr
Dec.: –10.99[1] mas/yr
Parallax (π) 2.47 ± 0.50[1] mas
Distance approx. 1,300 ly
(approx. 400 pc)
Other designations
FK5 642, HD 156190, HIP 84979, HR 6411, SAO 257491.[5]

Iota Apodis (ι Aps, ι Apodis) is the Bayer designation for a binary star[3] system in the southern circumpolar constellation of Apus. It is a faint target at an apparent visual magnitude of 5.41,[2] but still visible to the naked eye from suitably dark skies. The distance to this star can be roughly gauged from parallax measurements, yielding an estimate of 1,300 light-years (400 parsecs) with a 20% margin of error.[1]

Both stars are B-type main sequence stars, which indicates they shine with a blue-white hue.[6] The brighter component has a stellar classification of B9 V and an apparent magnitude 5.90, while the second member is a B9.5 V star with a magnitude of 6.46. The pair have an angular separation of 0.091 arcseconds[3] with a preliminary estimated orbital period of 51.441 years.[7] They are 3.89 ± 1.02 and 3.45 ± 0.90 times as massive as the Sun.[8]


In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of ι Apodis, ζ Apodis, β Apodis, γ Apodis, δ Octantis, δ1 Apodis, η Apodis, α Apodis and ε Apodis. Consequently, ι Apodis itself is known as 異雀二 (Yì Què èr, English: the Second Star of Exotic Bird.)[9]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752free to read, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N. 
  3. ^ a b c d 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:0806.2878free to read, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  4. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W. 
  5. ^ "iot Aps -- Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-09. 
  6. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16 
  7. ^ Olević, D.; Cvetković, Z. (February 2004), "Orbits of 10 interferometric binary systems calculated by using the improved Koval'skij method", Astronomy and Astrophysics, 415: 259–264, Bibcode:2004A&A...415..259O, doi:10.1051/0004-6361:20034069. 
  8. ^ Docobo, J.A.; Andrade, M. (2013). "Dynamical and physical properties of 22 binaries discovered by W. S. Finsen". Monthly Notices of the Royal Astronomical Society. 428 (1): 321–39. Bibcode:2013MNRAS.428..321D. doi:10.1093/mnras/sts045. 
  9. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 29 日

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