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]
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] |
Characteristics | |
Spectral type | B9 V + B9.5 V[3] |
U−B color index | −0.23[2] |
B−V color index | −0.04[2] |
Astrometry | |
Radial velocity (Rv) | −4.3[4] km/s |
Proper motion (μ) | RA: −1.844 ± 0.266[5] mas/yr Dec.: −10.811 ± 0.303[5] mas/yr |
Parallax (π) | 3.1403 ± 0.1782 mas[5] |
Distance | 1,040 ± 60 ly (320 ± 20 pc) |
Orbit[6] | |
Period (P) | 59.32±3.0 yr |
Semi-major axis (a) | 0.115±0.005″ |
Eccentricity (e) | 0.172±0.050 |
Inclination (i) | 69.4±3.0° |
Longitude of the node (Ω) | 119.6±4.0° |
Argument of periastron (ω) (secondary) | 270.5±7.0° |
Details | |
ι Aps A | |
Mass | 3.89±1.02[6] M☉ |
ι Aps B | |
Mass | 3.45±0.90[6] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
Both stars are B-type main sequence stars, which indicates they shine with a blue-white hue.[8] 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 an estimated orbital period of 59.32 years. They are about 3.89 and 3.45 times as massive as the Sun.[6]
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]
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