Iota2 Scorpii

For other stars with this Bayer designation, see ι Scorpii

ι² Scorpii, Latinised as Iota² Scorpii, is a single^[11] star in tail of the zodiac constellation of Scorpius. It has an apparent visual magnitude of +4.82,^[2] and is visible to the naked eye. Because of parallax measurement errors, the distance to this star is only approximately known: it lies around 2,500 light years away from the Sun. It has a visual companion, a magnitude 11.0 star at an angular separation of 31.60 arcseconds along a position angle of 36°, as of 2000.^[12]

ι² Scorpii

Observation data Epoch J2000      Equinox J2000
Constellation	Scorpius
Right ascension	17h 50m 11.11291s[1]
Declination	−40° 05′ 25.5629″[1]
Apparent magnitude (V)	+4.82[2]
Characteristics
Spectral type	A2 Ib[3] or A6 Ib[4]
U−B color index	+0.19[2]
B−V color index	+0.25[2]
Astrometry
Radial velocity (Rv)	−10.2[5] km/s
Proper motion (μ)	RA: +3.90[1] mas/yr Dec.: −2.42[1] mas/yr
Parallax (π)	1.28±0.24 mas[1]
Distance	approx. 2,500 ly (approx. 800 pc)
Absolute magnitude (MV)	−4.59[6]
Details
Mass	8.8±0.2[4] M☉
Radius	78[7] R☉
Luminosity	5,798[8] L☉
Surface gravity (log g)	1.68[9] cgs
Temperature	8,246[7] K
Metallicity [Fe/H]	−0.33[9] dex
Age	29.8±4.3[4] Myr
Other designations
ι2 Sco, CD−40°11886, HD 161912, HIP 87294, HR 6631, SAO 228466[10]
Database references
SIMBAD	data

In the literature, there are two different stellar classifications for this star: A2 Ib^[3] and A6 Ib.^[4] In either case it is an A-type supergiant star with an estimated age of 30^[4] million years and a mass 8.8 times that of the Sun.^[4] It shines with a luminosity 5,798 times the Sun's from an outer atmosphere that has an effective temperature of 8,246 K.^[7] As with other stars of its type, ι² Scorpii varies slightly in brightness, showing an amplitude of 0.05 in magnitude.^[13]