Iota Gruis

Iota Gruis, Latinized from ι Gruis, is a binary star^[6] system in the southern constellation of Grus. It has an apparent visual magnitude of 3.90,^[2] which is bright enough to be seen with the naked eye at night. The distance to this system, as determined using an annual parallax shift of 17.80 mas as seen from the Earth,^[1] is about 183 light years.

Iota Gruis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Grus
Right ascension	23h 10m 21.53755s[1]
Declination	−45° 14′ 48.1647″[1]
Apparent magnitude (V)	3.90[2]
Characteristics
Spectral type	K1 III[3]
U−B color index	+0.86[2]
B−V color index	+1.02[2]
Astrometry
Radial velocity (Rv)	−4.4[4] km/s
Proper motion (μ)	RA: +132.50[1] mas/yr Dec.: −26.66[1] mas/yr
Parallax (π)	17.80±0.33 mas[1]
Distance	183 ± 3 ly (56 ± 1 pc)
Absolute magnitude (MV)	+0.13[5]
Orbit[6][7]
Period (P)	409.614 d
Semi-major axis (a)	7.82±0.47 mas
Eccentricity (e)	0.66
Inclination (i)	114.3±5.2°
Periastron epoch (T)	2416115.569 JD
Argument of periastron (ω) (secondary)	240.8°
Semi-amplitude (K1) (primary)	13.6 km/s
Details[8]
ι Gru A
Mass	2.97±0.16 M☉
Radius	12.38±0.53 R☉
Luminosity	83.9±5.5 L☉
Surface gravity (log g)	2.709±0.143 cgs
Temperature	4,966±69 K
Metallicity [Fe/H]	+0.150±0.054 dex
Other designations
ι Gru, CD−45°14947, FK5 1605, HD 218670, HIP 114421, HR 8820, SAO 231468[9]
Database references
SIMBAD	data

This is a single-lined spectroscopic binary with an orbital period of 409.6 days (1.121 years) and an eccentricity of 0.66.^[6] The yellow-hued primary component is an evolved K-type giant star with a stellar classification of K1 III.^[3] It is an X-ray emitter with a flux of 441.31×10⁻¹⁷ W/m².^[10]