Iota1 Normae

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]

For other star systems with this Bayer designation, see ι Normae.

ι¹ Normae

Observation data Epoch J2000.0      Equinox J2000.0 (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
Companion	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
Companion	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]