Iota Trianguli

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Iota Trianguli
Triangulum IAU.svg
Red circle.svg
Location of ι Trianguli (circled)
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Triangulum
A
Right ascension 02h 12m 22.2797s [1]
Declination +30° 18′ 11.053″ [1]
Apparent magnitude  (V)5.32 [2]
B
Right ascension 02h 12m 22.5637s [3]
Declination +30° 18′ 12.342″ [3]
Apparent magnitude  (V)6.83 [2]
Characteristics
A
Spectral type G0 III + G5 III [4]
B−V color index +0.856 [5]
Variable type ellipsoidal + RS CVn [6]
B
Spectral type F5V + ? [2]
B−V color index +0.515 [5]
Astrometry
A
Proper motion (μ)RA: −64.350 [1] mas/yr
Dec.: −59.503 [1] mas/yr
Parallax (π)11.3011±0.1024  mas [1]
Distance 289 ± 3  ly
(88.5 ± 0.8  pc)
B
Proper motion (μ)RA: −64.414 [3] mas/yr
Dec.: −49.913 [3] mas/yr
Parallax (π)12.7375±0.5496  mas [3]
Distance 260 ± 10  ly
(79 ± 3  pc)
Absolute magnitude  (MV)+0.20 [7]
Orbit [8]
PrimaryAa
CompanionAb
Period (P)14.73018 days
Semi-major axis (a)0.002 [9] ″
Eccentricity (e)0.0035
Inclination (i)55 –58 [9] °
Semi-amplitude (K1)
(primary)		54.84 km/s
Semi-amplitude (K2)
(secondary)		56.39 km/s
Orbit [10]
PrimaryBa
CompanionBb
Period (P)2.2365 days
Eccentricity (e)0
Semi-amplitude (K1)
(primary)		95.4 km/s
Semi-amplitude (K2)
(secondary)		101.0 km/s
Details
Aa
Mass 2.50 [9]   M☉
Radius 4.0 [8]   R☉
Luminosity 61.7 [8]   L☉
Temperature 4,932 [8]   K
Rotational velocity (v sin i)32.9 [8]  km/s
Ab
Mass 2.43 [9]   M☉
Radius 1.5 [8]   R☉
Luminosity10.0 [8]   L☉
Temperature 6,486 [8]   K
Rotational velocity (v sin i)3.0 [8]  km/s
Ba
Mass 1.58 [9]   M☉
Bb
Mass 1.56 [9]   M☉
Other designations
Triminus, ι Tri, 6 Tri, TZ Tri, BD+29°371, HD 13480, HIP 10280, HR 642, SAO 55347, WDS J02124+3018 [11]
Database references
SIMBAD data

Iota Trianguli, also named Triminus, [12] is a quadruple [2] star system in constellation of Triangulum. The pair have a combined apparent magnitude of 4.95 [13] and are approximately 290 light-years from Earth.

Contents

A light curve for Iota Trianguli, plotted from Hipparcos data IotaTriLightCurve.png
A light curve for Iota Trianguli, plotted from Hipparcos data

Both components of ι Trianguli are spectroscopic binaries and the brighter pair is variable. It was discovered to be a variable star in 1980, by Douglas S. Hall et al. [15] It has been given the variable star designation TZ Trianguli. The variations are due to the ellipsoidal shape of the stars as they rotate, and also it is classified as an RS Canum Venaticorum variable. [16]

Nomenclature

Iota Trianguli, Latinized from ι Trianguli, is the star's Bayer designation; it is also known by the Flamsteed designation 6 Trianguli. Together with 10 Trianguli and 12 Trianguli, it formed part of the obsolete constellation Triangulum Minus.

The Latin name "Triminus" is composed of the IAU abbrevation of "Tri" for Triangulum and "Minus" for Triangulum Minus, or the lesser triangle made by Johannes Hevelius. The IAU Working Group on Star Names approved the name Triminus for this star on 25 August 2025 and it is now so entered in the IAU Catalog of Star Names. [12]

References

  1. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 4 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. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  4. ↑ Harlan, E. A. (September 1969), "MK classifications for F- and G-type stars. I", Astronomical Journal, 74: 916–919, Bibcode:1969AJ.....74..916H, doi:10.1086/110881.
  5. 1 2 Myers, J. R.; Sande, C. B.; Miller, A. C.; Warren, W. H.; Tracewell, D. A. (2015), "VizieR Online Data Catalog: SKY2000 Master Catalog, Version 5 (Myers+ 2006)", Vizier Online Data Catalog, Bibcode:2015yCat.5145....0M.
  6. ↑ Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports , 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  7. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID   119257644.
  8. 1 2 3 4 5 6 7 8 9 Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi: 10.1088/0004-6256/135/1/209 , S2CID   121883397.
  9. 1 2 3 4 5 6 Tokovinin, Andrei (23 February 2018), "The Updated Multiple Star Catalog", The Astrophysical Journal Supplement Series, 235 (1): 6, arXiv: 1712.04750 , Bibcode:2018ApJS..235....6T, doi: 10.3847/1538-4365/aaa1a5 , eISSN   1538-4365.
  10. ↑ Luyten, W. J. (July 1936), "A rediscussion of the orbits of seventy-seven spectroscopic binaries", Astrophysical Journal, 84: 85, Bibcode:1936ApJ....84...85L, doi: 10.1086/143751 .
  11. ↑ "iot Tri", SIMBAD , Centre de données astronomiques de Strasbourg , retrieved 2017-06-30.
  12. 1 2 "IAU Catalog of Star Names" . Retrieved 26 August 2025.
  13. ↑ Rakos, K. D.; et al. (February 1982), "Photometric and astrometric observations of close visual binaries", Astronomy and Astrophysics Supplement Series, 47: 221–235, Bibcode:1982A&AS...47..221R.
  14. ↑ "Light Curve", Hipparcos ESA, ESA, retrieved 13 September 2022.
  15. ↑ Hall, D. S.; Henry, G. W.; Louth, H.; Lovell, L. P.; Stephan, C. (March 1980). "6 iota Trianguli: a new variable star" (PDF). Information Bulletin on Variable Stars. 1764. Retrieved 27 August 2025.
  16. ↑ Hall, D. S.; et al. (1980), "6 iota Trianguli: A new variable star", Information Bulletin on Variable Stars, 1764: 1, Bibcode:1980IBVS.1764....1H.
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