Iota Crucis

ι Crucis, Latinized as Iota Crucis, is a wide double star in the southern constellation of Crux.[6] It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4m.69.[2] This object is located 125 light-years from the Sun, based on parallax, and is drifting further away with a radial velocity of +7.5 km/s.[1]

Iota Crucis
Observation data
Epoch J2000      Equinox J2000
Constellation Crux
Right ascension  12h 45m 38.05019s[1]
Declination −60° 58′ 52.7536″[1]
Apparent magnitude (V) 4.69[2]
Characteristics
Spectral type K0 III[3]
U−B color index +0.93[4]
B−V color index +1.05[4]
Astrometry
Radial velocity (Rv)+7.45±0.12[1] km/s
Proper motion (μ) RA: 112.968[1] mas/yr
Dec.: −65.830[1] mas/yr
Parallax (π)26.0909 ± 0.2150[1] mas
Distance125 ± 1 ly
(38.3 ± 0.3 pc)
Absolute magnitude (MV)+1.86[2]
Details
ι Cru A
Radius7.26+0.23
−0.25[1] R☉
Luminosity24.0±0.2[1] L☉
Surface gravity (log g)2.79±0.22[5] cgs
Temperature4,824±44[5] K
Metallicity [Fe/H]+0.07±0.03[5] dex
Other designations
ι Cru, CPD–60°4273, HD 110829, HIP 62268, HR 4842, SAO 252016[6]
Database references
SIMBADdata

The primary component is an aging giant star with a stellar classification of K0 III.[3] Having exhausted the supply of hydrogen at its core, the star has cooled and expanded off the main sequence, and now has over seven times the girth of the Sun. It is radiating 24 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,824 K.[1]

The secondary is a magnitude 10.24 star at an angular separation of 29.7″ from the primary along a position angle of 2°, as of 2015. The Washington Double Star Catalog (2001) notes this is an "optical pair, based on study of relative motion of the components,"[7] whereas Eggleton and Tokovinin (2008) list it as a binary system.[8] Gaia Data Release 2 gives a parallax of 1.0868±0.0391 mas for the companion, implying a distance around 1,000 pc.[9]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H
  4. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  5. Alves, S.; et al. (April 2015), "Determination of the spectroscopic stellar parameters for 257 field giant stars", Monthly Notices of the Royal Astronomical Society, 448 (3): 2749–2765, arXiv:1503.02556, Bibcode:2015MNRAS.448.2749A, doi:10.1093/mnras/stv189.
  6. "iot Cru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-04.
  7. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  8. 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.
  9. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
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