Iota Gruis
Star in the constellation Grus
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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.
 | |
| 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]