Iota Aquilae
Star in the constellation Aquila
From Wikipedia, the free encyclopedia
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".[11] With an apparent visual magnitude of 4.364,[3] this star is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 5.67±0.19 mas,[2] it is located at a distance of around 580 light-years (180 parsecs) from Earth.[2] The visual magnitude of the star is diminished by 0.15 from extinction caused by intervening gas and dust.[7]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Aquila[1] |
| Right ascension | 19h 36m 43.2777s[2] |
| Declination | −01° 17′ 11.759″[2] |
| Apparent magnitude (V) | 4.364[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | B5 III[4] or B6 IV[5] |
| U−B color index | −0.428[3] |
| B−V color index | −0.083[3] |
| R−I color index | −0.08[6] |
| Astrometry | |
| Radial velocity (Rv) | −21.34±3.63[2] km/s |
| Proper motion (μ) | RA: −1.426 mas/yr[2] Dec.: −21.644 mas/yr[2] |
| Parallax (π) | 5.6673±0.1947 mas[2] |
| Distance | 580 ± 20 ly (176 ± 6 pc) |
| Absolute magnitude (MV) | −1.01[1] |
| Details | |
| Mass | 4.8±0.3[7] M☉ |
| Radius | 7.8±0.9[8] R☉ |
| Luminosity | 851[7] L☉ |
| Surface gravity (log g) | 3.64±0.05[7] cgs |
| Temperature | 14,500±600[8] K |
| Metallicity [Fe/H] | 0.09±0.04[1] dex |
| Rotational velocity (v sin i) | 55[9] km/s |
| Age | 100 ± 8[7] 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[10] | |
| Database references | |
| SIMBAD | data |
In 1968, this star was assigned a stellar classification of B5III,[4] 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.[7] In 2024, a study of standard stars suggested that Iota Aquilae be classified as B6 IV, matching a subgiant star.[5]
Iota Aquilae has nearly five times the mass of the Sun[7] and eight times the Sun's radius.[8] It is emitting 851 times the luminosity of the Sun from its outer atmosphere[7] at an effective temperature of 14,500 K,[12] giving it the blue-white hue of a B-type star.[13] The projected rotational velocity of this star is 55 km/s.[9]
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.[14] Consequently, the Chinese name for ι Aquilae itself is 右旗五 (Yòu Qí wu, English: the Fifth Star of Right Flag.)[15]
This star, together with η Aql, θ Aql, δ Aql, κ Aql and λ Aql were once part of the obsolete constellation Antinous.[16]