Iota Centauri

ι Centauri
Location of ι Centauri (circled)
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Centaurus
Right ascension 13h 20m 35.81737s
Declination −36° 42′ 44.2447″
Apparent magnitude (V) +2.73
Characteristics
Evolutionary stage main sequence
Spectral type A2 V (kA1.5hA3mA3va)
U−B color index +0.01
B−V color index +0.03
Astrometry
Radial velocity (Rv)+0.1 km/s
Proper motion (μ) RA: −341.11 mas/yr
Dec.: −86.14 mas/yr
Parallax (π)55.49±0.17 mas
Distance58.8 ± 0.2 ly
(18.02 ± 0.06 pc)
Absolute magnitude (MV)+1.47
Details
Mass2.03±0.03 M☉
Radius1.9 ± 0.05 R☉
Luminosity22.91+1.08
−1.03 L☉
Surface gravity (log g)4.11 cgs
Temperature9,160±70 K
Metallicity [Fe/H]–0.46 dex
Rotational velocity (v sin i)90.3 km/s
Age0.35 Gyr
Other designations
Kulou, ι Cen, CD−36°8497, FK5 496, GJ 508.1, GJ 9441, HD 115892, HIP 65109, HR 5028, SAO 204371
Database references
SIMBADdata

Iota Centauri is a star in the southern constellation of Centaurus. It has the proper name Kulou; Iota Centauri is its Bayer designation, which is Latinized from ι Centauri and is abbreviated Iota Cen or ι Cen. Based upon parallax measurements, it lies at a distance of approximately 58.6 light-years (18.0 parsecs) from Earth. Iota Centauri has an apparent visual magnitude of +2.73, making it easily visible to the naked eye.

The spectrum of ι Centauri matches a stellar classification of A2 V. It is an A-type main sequence star that is generating energy by the nuclear fusion of hydrogen in its core region. This energy is being radiated from the outer envelope of the star at an effective temperature of 9,160 K, giving the star a white hue. It has about 2 times the Sun's mass, 1.9 times the Sun's radius, and is roughly 350 million years old. The abundance of elements other than hydrogen and helium, what astronomers term the metallicity, is only 35% of the abundance in the Sun. A weak magnetic field has been tentatively identified with a strength of −77 ± 30 G.

This star has an excess emission of infrared indicating it is surrounded by a circumstellar disk of dust, known as a debris disk. The disk is located within an orbital radius of six Astronomical Units from the star. The dust is unusually luminous for a star this age, suggesting that some process may have recently increased the amount of debris, such as collisions between planetesimals. Alternatively, the planetesimals in this system may have unusual physical properties. As of 2011, a search for planets in this system has thus far been unsuccessful.

Iota Centauri appears to belong to the stellar kinematic group known as IC 2391. This is a group of around 16 co-moving stars that most likely originated in the same molecular cloud at least 45 million years ago.

Nomenclature

In Chinese, 柱 (Zhǔ), meaning Pillars, refers to an asterism consisting of ι Centauri, υ2 Centauri, υ1 Centauri, a Centauri, ψ Centauri, 4 Centauri, 3 Centauri and 1 Centauri. Consequently, the Chinese name for ι Centauri itself is 柱十一 (Zhǔ shíyī, English: the Eleventh Star of Pillars.)

In older Chinese sources, this star was a member of the ancient super-constellation Kulou (库楼, The Arsenal), in the area of modern Centaurus and Lupus, dating back to the 2nd century BCE. Later, ζ Centauri was identified as the main star of Kulou. The IAU Working Group on Star Names approved the name Kulou for this star on 17 February 2025 and it is now so entered in the IAU Catalog of Star Names.

Notes

  1. ↑ Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:

References

  1. 1 2 3 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. XHIP record for this object at VizieR.
  2. 1 2 3 4 5 6 van Leeuwen, F. (November 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.
  3. 1 2 3 4 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  4. ↑ Hardegree-Ullman, Kevin K.; et al. (2023), "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets", The Astronomical Journal, 165 (6): 267, arXiv:2304.12490, Bibcode:2023AJ....165..267H, doi:10.3847/1538-3881/acd1ec.
  5. ↑ Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
  6. ↑ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
  7. 1 2 3 4 5 6 Pearce, Tim D.; et al. (2022-03-01), "Planet populations inferred from debris discs. Insights from 178 debris systems in the ISPY, LEECH, and LIStEN planet-hunting surveys", Astronomy and Astrophysics, 659: A135, arXiv:2201.08369, Bibcode:2022A&A...659A.135P, doi:10.1051/0004-6361/202142720, ISSN 0004-6361.
  8. 1 2 3 Saffe, C.; et al. (October 2008), "Spectroscopic metallicities of Vega-like stars", Astronomy and Astrophysics, 490 (1): 297–305, arXiv:0805.3936, Bibcode:2008A&A...490..297S, doi:10.1051/0004-6361:200810260, S2CID 15059920.
  9. ↑ Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386, S2CID 119286673.
  10. 1 2 3 Quanz, Sascha P.; et al. (August 2011), "Searching for Gas Giant Planets on Solar System Scales: VLT NACO/APP Observations of the Debris Disk Host Stars HD172555 and HD115892", The Astrophysical Journal Letters, 736 (2): L32, arXiv:1106.4528, Bibcode:2011ApJ...736L..32Q, doi:10.1088/2041-8205/736/2/L32, S2CID 118506333.
  11. ↑ "iot Cen", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-02-02.
  12. 1 2 3 IAU Catalog of Star Names, retrieved 22 February 2025.
  13. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16.
  14. ↑ Hubrig, S.; et al. (February 2006), "Accurate magnetic field measurements of Vega-like stars and Herbig Ae/Be stars", Astronomy and Astrophysics, 446 (3): 1089–1094, arXiv:astro-ph/0510157, Bibcode:2006A&A...446.1089H, doi:10.1051/0004-6361:20053794, S2CID 14669402.
  15. ↑ Nakajima, Tadashi; et al. (September 2010), "Potential Members of Stellar Kinematical Groups within 20 pc of the Sun", The Astronomical Journal, 140 (3): 713–722, Bibcode:2010AJ....140..713N, doi:10.1088/0004-6256/140/3/713.
  16. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  17. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日 Archived 2011-05-22 at the Wayback Machine
  18. 1 2 "Kulou (库楼)", All Skies Encyclopaedia, IAU Working Group on Star Names, retrieved 6 May 2025.