Iota Aquilae

Iota Aquilae
Location of ι Aquilae (circled)
Observation data
Epoch J2000      Equinox ICRS
Constellation Aquila
Right ascension 19h 36m 43.2777s
Declination −01° 17′ 11.759″
Apparent magnitude (V) 4.364
Characteristics
Evolutionary stage main sequence
Spectral type B5 III or B6 IV
U−B color index −0.428
B−V color index −0.083
R−I color index −0.08
Astrometry
Radial velocity (Rv)−21.34±3.63 km/s
Proper motion (μ) RA: −1.426 mas/yr
Dec.: −21.644 mas/yr
Parallax (π)5.6673±0.1947 mas
Distance580 ± 20 ly
(176 ± 6 pc)
Absolute magnitude (MV)−1.01
Details
Mass4.8±0.3 M☉
Radius7.8±0.9 R☉
Luminosity851 L☉
Surface gravity (log g)3.64±0.05 cgs
Temperature14,500±600 K
Metallicity [Fe/H]0.09±0.04 dex
Rotational velocity (v sin i)55 km/s
Age100 ± 8 Myr
Other designations
Al Thalimain, ι Aquilae, Iota Aql, ι Aql, 41 Aql, GC 27103, HD 184930, HIP 96468, HR 7447, SAO 143597, PPM 180738, WDS J19367-0117A
Database references
SIMBADdata

Iota Aquilae is a star in the equatorial constellation of Aquila. Its identifier is a Bayer designation that is Latinized from ι Aquilae, and abbreviated Iota Aql or ι Aql. The star has the traditional name Al Thalimain, pronounced /ælˌθælɪˈmeɪn/, which it shares with λ Aquilae. The name is derived from the Arabic term الظليمین al-ẓalīmayn meaning "The Two Ostriches". With an apparent visual magnitude of 4.364, this star is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 5.67±0.19 mas, it is located at a distance of around 580 light-years (180 parsecs) from Earth. The visual magnitude of the star is diminished by 0.15 from extinction caused by intervening gas and dust.

In 1968, this star was assigned a stellar classification of B5III, which suggests it has exhausted its hydrogen supply at its core and evolved into a blue giant. However, stellar models from 2002 indicate it is around 100 million years old and has thus far spent 91% of its allotted lifetime on the main sequence. In 2024, a study of standard stars suggested that Iota Aquilae be classified as B6 IV, matching a subgiant star.

Iota Aquilae has nearly five times the mass of the Sun and eight times the Sun's radius. It is emitting 851 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 14,500 K, giving it the blue-white hue of a B-type star. The projected rotational velocity of this star is 55 km/s.

Nomenclature

In Chinese, 右旗 (Yòu Qí), meaning Right Flag, refers to an asterism consisting of ι Aquilae, μ Aquilae, σ Aquilae, δ Aquilae, ν Aquilae, 42 Aquilae, HD 184701, κ Aquilae and 56 Aquilae. Consequently, the Chinese name for ι Aquilae itself is 右旗五 (Yòu Qí wu, English: the Fifth Star of Right Flag.)

This star, together with η Aql, θ Aql, δ Aql, κ Aql and λ Aql were once part of the obsolete constellation Antinous.

References

  1. 1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  2. 1 2 3 4 5 6 7 8 9 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.
  3. 1 2 3 4 Kozok, J. R. (September 1985), "Photometric observations of emission B-stars in the southern Milky Way", Astronomy and Astrophysics Supplement Series, 61: 387–405, Bibcode:1985A&AS...61..387K.
  4. 1 2 Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179.
  5. 1 2 Negueruela, I.; et al. (2024), "The IACOB project: XII. New grid of northern standards for the spectral classification of B-type stars", Astronomy and Astrophysics, 690, id. A176, arXiv:2407.04163, Bibcode:2024A&A...690A.176N, doi:10.1051/0004-6361/202449298.
  6. ↑ Mallama, A. (2014), "Sloan Magnitudes for the Brightest Stars", Journal of the American Association of Variable Star Observers (Jaavso), 42 (2): 443, Bibcode:2014JAVSO..42..443M.
  7. 1 2 3 4 5 6 7 8 Lyubimkov, Leonid S.; et al. (June 2002), "Surface abundances of light elements for a large sample of early B-type stars - II. Basic parameters of 107 stars", Monthly Notices of the Royal Astronomical Society, 333 (1): 9–26, Bibcode:2002MNRAS.333....9L, doi:10.1046/j.1365-8711.2002.05341.x.
  8. 1 2 3 Gordon, Kathryn D.; et al. (March 2019), "Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array", The Astrophysical Journal, 873 (1): 91, Bibcode:2019ApJ...873...91G, doi:10.3847/1538-4357/ab04b2, S2CID 125181833.
  9. 1 2 Abt, Helmut A.; et al. (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
  10. ↑ "iot Aql", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-07-18.
  11. ↑ "Patronage for Star #96165 | Patronize a star | OpenSea".
  12. ↑ Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189 (3): 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601.
  13. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-01-16.
  14. ↑ (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.
  15. ↑ "AEEA 天文教育資訊網". Archived from the original on 3 December 2013. Retrieved 1 September 2024.
  16. ↑ Ridpath, Ian, "Antinous", Ian Ridpath's Star Tales, retrieved 2025-04-18.