Epoch J2000 Equinox J2000
|Right ascension||17h 23m 16.07715s|
|Declination||–47° 28′ 05.5073″|
|Apparent magnitude (V)||5.245|
|Spectral type||B2 IIIne|
|U−B color index||–0.82|
|B−V color index||–0.11|
|R−I color index||–0.08|
|Variable type||γ Cas|
|Radial velocity (Rv)||–19 km/s|
|Proper motion (μ)||RA: –4.35 mas/yr
Dec.: –17.59 mas/yr
|Parallax (π)||3.49 ± 0.26 mas|
|Distance||930 ± 70 ly
(290 ± 20 pc)
|Mass||8.3 ± 0.4 M☉|
|Luminosity (bolometric)||5,740 L☉|
|Surface gravity (log g)||4.10 cgs|
|Rotational velocity (v sin i)||375 km/s|
|Age||30.0 ± 7.4 Myr|
Iota Arae (ι Ara, ι Arae) is the Bayer designation for a star in the southern constellation of Ara. It is approximately 930 light-years (290 parsecs) from Earth, give or take a 70 light-year margin of error, and has an apparent visual magnitude of 5.25. Based upon the Bortle Dark-Sky Scale, this means the star is visible to the naked eye from suburban skies.
This is an evolved giant star with a stellar classification of B2 IIIne. The 'e' notation indicates the spectrum displays emission lines, which means this is a Be star that is surrounded by hot, circumstellar gas. It is spinning rapidly with a projected rotational velocity of 375 km/s. The Doppler effect from this rotation is causing the absorption lines to widen and become nebulous, as indicated by the 'n' notation in the stellar class.
Iota Arae has around 8.3 times the mass of the Sun and is shining brightly with 5,740 times the Sun's luminosity. This energy is being radiated into space from the outer atmosphere at an effective temperature of 21,380 K, giving it the characteristic blue-white hue of a B-type star. It is classified as a Gamma Cassiopeiae-type variable star and its brightness varies by 0.054 in magnitude.
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