Iota1 Normae

Iota1 Normae (ι1 Normae) is a triple star[2] system in the southern constellation of Norma. With a combined apparent visual magnitude of 4.69,[2] it is faintly visible to the naked eye. Based upon an annual parallax shift of 25.39 mas as seen from Earth,[1] this system is located about 128 light years from the Sun. At that distance, the visual magnitude of these stars is diminished by an extinction factor of 0.062 due to interstellar dust.[3]

For other star systems with this Bayer designation, see ι Normae.
Iota1 Normae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Norma
Right ascension 16h 03m 32.08942s[1]
Declination −57° 46′ 30.2641″[1]
Apparent magnitude (V) 4.69 (5.20 + 5.76 + 8.1)[2]
Characteristics
Spectral type A7 IV[3] (A4 V + A6 V)[4]
Astrometry
Radial velocity (Rv)−14.4±3.7[5] km/s
Proper motion (μ) RA: −120.01[1] mas/yr
Dec.: −82.09[1] mas/yr
Parallax (π)25.39 ± 1.25 mas[1]
Distance128 ± 6 ly
(39 ± 2 pc)
Orbit[6]
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°
Details
ι1 Nor A
Mass1.94[7] M☉
Surface gravity (log g)4.25[8] cgs
Temperature7,842±267[8] K
Age731[8] Myr
ι1 Nor B
Mass1.65[7] M☉
Other designations
ι1 Nor, CPD−57° 7500, HD 143474, HIP 78662, HR 5961, SAO 243279, WDS J16035-5747AB[9]
Database references
SIMBADdata

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. They have a blended stellar classification of A7 IV,[3] matching a white-hued A-type subgiant star. Both stars are actual A-type main sequence stars. The brighter of the pair, magnitude 5.20[2] component A, has a spectral class of A4 V,[4] while its magnitude 5.76[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.[3] The tertiary member, component C, is a magnitude 8.1[2] star with 0.88 times the mass of the Sun.[7] It lies at an angular separation of 10.8 arc seconds from the other members.

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  3. Malkov, O. Yu.; et al. (2012), "Dynamical masses of a selected sample of orbital binaries", Astronomy & Astrophysics, 546: A69, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774.
  4. Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  6. Tokovinin, Andrei; et al. (August 2015), "Speckle Interferometry at SOAR in 2014", The Astronomical Journal, 150 (2): 17, arXiv:1506.05718, Bibcode:2015AJ....150...50T, doi:10.1088/0004-6256/150/2/50, S2CID 30737411, 50.
  7. Tokovinin, A. (September 2008), "Comparative statistics and origin of triple and quadruple stars", Monthly Notices of the Royal Astronomical Society, 389 (2): 925–938, arXiv:0806.3263, Bibcode:2008MNRAS.389..925T, doi:10.1111/j.1365-2966.2008.13613.x, S2CID 16452670.
  8. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  9. "iot01 Nor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-12.{{cite web}}: CS1 maint: postscript (link)
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