Omicron1 Centauri

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Star in the constellation Centaurus

title: "Omicron1 Centauri" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["g-type-hypergiants", "semiregular-variable-stars", "centaurus", "bayer-objects", "bright-star-catalogue-objects", "durchmusterung-objects", "henry-draper-catalogue-objects", "hipparcos-objects"] description: "Star in the constellation Centaurus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Omicron1_Centauri" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star in the constellation Centaurus ::

| name = ο1 Centauri | image = |image=Centaurus constellation map.svg |float=center |alt= |label= |position=right |width=280 |mark=Red circle.svg |mark_width=10 |mark_link=ο1 Centauri |x=840|y=894 | caption = Location of ο1 Cen (circled) | epoch = J2000.0 | constell = Centaurus | ra = | dec = | appmag_v = +5.13 | class = G3 0-Ia | b-v = +1.08 | u-b = | variable = SRd | type = Yellow hypergiant | radial_v = −20.00 | prop_mo_ra = −4.491 | prop_mo_dec = +1.604 | pm_footnote = | parallax = 0.3254 | p_error = 0.0734 | parallax_footnote = | dist_ly = | dist_pc = | dist_footnote = | absmag_v = −9.0 | mass = | radius = | luminosity = 68,000 | temperature = 5,700 | metal_fe = | gravity = 0.19 | rotational_velocity = | age_myr = 10–12 | names = | Simbad = HD+100261

Omicron1 Centauri is a star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from ο1 Centauri, and abbreviated Omicron1 Cen or ο1 Cen. It is approximately 10,000 light years from Earth, though this is very uncertain.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/76/Omicron1CenLightCurve.png" caption="A [[light curve]] for Omicron1 Centauri, adapted from O'Connell (1961)<ref name="O'Connell"/>"] ::

ο1 Centauri is a yellow G-type supergiant or hypergiant with a mean apparent magnitude of +5.13. Daniel Joseph Kelly O'Connell discovered that the star is a variable star by studying photographic plates taken from 1934 to 1952, and announced his discovery in 1961. It is classified as a semiregular variable star and its brightness varies from magnitude +5.8 to +6.6 with a period of 200 days. Other studies have reported only small brightness variations. It is the MK spectral standard for class G3 O-Ia, indicating a highly luminous mass-losing hypergiant star. It has also be classified as F8 Ia0 and F7 Ia/ab. The size, luminosity, and distance are equally uncertain.

ο1 Cen forms a very close naked eye double star with ο2 Centauri, a hotter blue supergiant that may be physically associated. ο1 Cen also has an 11th magnitude companion only 13.5" distant, although it appears to be a foreground star unrelated to the other two. ο1 Cen is located very close to V382 Carinae, the brightest yellow hypergiant star in the night sky.

References

References

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  2. {{cite Gaia DR3. 5336490478704007936
  3. (2021). "Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3". The Astronomical Journal.
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  12. Gontcharov, G. A.. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters.
  13. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S.
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  15. (1997). "Quantitative spectral classification based on photoelectric spectrum scanner measurements of F-K stars". Astronomy and Astrophysics.
  16. Kaler, James B.. "Omicron 1,2 Centauri". University of Illinois.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::

g-type-hypergiantssemiregular-variable-starscentaurusbayer-objectsbright-star-catalogue-objectsdurchmusterung-objectshenry-draper-catalogue-objectshipparcos-objects