Iota1 Normae
Star in the constellation Norma
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Iota1 Normae (ι1 Normae) is a quadruple star system[7] in the southern constellation of Norma. With a combined apparent visual magnitude of 4.63,[2] it is faintly visible to the naked eye. Stellar parallax measurements give distances varying between 132.2 and 134.1 light-years. At that distance, the visual magnitude of these stars is diminished by an extinction of 0.062 magnitudes due to interstellar dust.[10]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Norma |
| ι1 Nor AB | |
| Right ascension | 16h 03m 32.08942s[1] |
| Declination | −57° 46′ 30.2641″[1] |
| Apparent magnitude (V) | 5.14 + 5.70[2] |
| ι1 Nor C | |
| Right ascension | 16h 03m 30.86534s[3] |
| Declination | −57° 46′ 35.2404″[3] |
| Apparent magnitude (V) | 8.02 (8.75 + 8.75)[2] |
| Characteristics | |
| ι1 Nor AB | |
| Spectral type | A4 V + A6 V[4] |
| ι1 Nor C | |
| Spectral type | G8V + K4V[5] |
| Variable type | suspected RS CVn[5] |
| Astrometry | |
| ι1 Nor AB | |
| Radial velocity (Rv) | −14.4±3.7[6] km/s |
| Proper motion (μ) | RA: −120.01[1] mas/yr Dec.: −82.09[1] mas/yr |
| Parallax (π) | 24.67 mas[7] |
| Distance | 132.2 ly (40.54 pc)[7] |
| ι1 Nor C | |
| Radial velocity (Rv) | −10.0±0.7[7] km/s |
| Proper motion (μ) | RA: −117.271 mas/yr[3] Dec.: −85.238 mas/yr[3] |
| Parallax (π) | 24.3136±0.0220 mas[3] |
| Distance | 134.1 ± 0.1 ly (41.13 ± 0.04 pc) |
| Orbit[8] | |
| Primary | ι1 Nor A |
| Name | ι1 Nor B |
| Period (P) | 26.84±0.09 yr |
| Semi-major axis (a) | 0.328±0.006″ |
| Eccentricity (e) | 0.515±0.012 |
| Inclination (i) | 168.7±9.9° |
| Longitude of the node (Ω) | 42.0±43.2° |
| Periastron epoch (T) | 1990.87±0.21 |
| Argument of periastron (ω) (secondary) | 320.0±44.1° |
| Orbit[7] | |
| Primary | ι1 Nor Ca |
| Name | ι1 Nor Cb |
| Period (P) | 0.82346(1) days |
| Semi-major axis (a) | 0.512 mas[2] |
| Eccentricity (e) | 0 (assumed) |
| Inclination (i) | ~45° |
| Argument of periastron (ω) (secondary) | 0 (assumed)° |
| Semi-amplitude (K1) (primary) | 107.0±1.2 km/s |
| Semi-amplitude (K2) (secondary) | 124.7±2.1 km/s |
| Details | |
| ι1 Nor A | |
| Mass | 1.75[2] M☉ |
| ι1 Nor B | |
| Mass | 1.54[2] M☉ |
| ι1 Nor Ca | |
| Mass | 0.88[2] M☉ |
| ι1 Nor Cb | |
| Mass | 0.88[2] M☉ |
| Other designations | |
| ι1 Nor, CPD−57°7500, HR 5961, WDS J16035-5747[9] | |
| AB: HD 143474, HIP 78662, SAO 243279 | |
| C: SAO 243278 | |
| Database references | |
| SIMBAD | data |
| C | |
The inner pair orbit each other with a period of 26.8 years, a semimajor axis of 0.33 arc seconds, and an eccentricity of 0.515. Both stars are A-type main sequence stars. The brighter of the pair, magnitude 5.14[2] component A, has a spectral class of A4 V,[4] while its magnitude 5.70[2] companion, component B, is of class A6 V.[4] The two are 1.94 and 1.65 times as massive as the Sun, respectively.[10] The tertiary member, component C, lies at an angular separation of 11.0 arc seconds from the other members.[2] It has an apparent magnitude of 8.02[2] and is itself a close binary, comprising two stars with an orbital period around 0.82 days,[7] each with an apparent magnitude of 8.75.[2]