Upsilon Carinae

---

title: "Upsilon Carinae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["a-type-supergiants", "b-type-subgiants", "double-stars", "carina-(constellation)", "bayer-objects", "bright-star-catalogue-objects", "durchmusterung-objects", "hipparcos-objects", "henry-draper-catalogue-objects"] description: "Binary star in the constellation Carina" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Upsilon_Carinae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Binary star in the constellation Carina ::

| name = υ Carinae | image = |image=Carina constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=υ Carinae |x=322|y=442 | caption = Location of υ Carinae (circled) | epoch = J2000 | ra = | dec = | appmag_v = 2.97 (+3.08/+6.25) | constell = Carina | type = | class = A8 Ib + B7 III | b-v = +0.27 | u-b = +0.13 | variable = | radial_v = +13.6 | prop_mo_ra = −11.51 | prop_mo_dec = +4.71 | parallax = 2.27 | p_error = 0.28 | parallax_footnote = | absmag_v = −5.26 | component1 = υ Car A | mass = 10.88 | radius = 96.6100 | luminosity = | temperature = | metal_fe = | gravity = | rotational_velocity = | age_myr = 23.4 | component2 = υ Car B | mass2 = 8 | temperature2 = | gravity2 = | names = | component2 = A | names2 = | component3 = B | names3 = HD 85123, HR 3891, SAO 250695 | Simbad=ups+Car | sn=system | Simbad2=ups+Car+A | sn2=A | Simbad3=ups+Car+B | sn3=B Upsilon Carinae is a double star in the southern constellation of Carina. Its name is a Bayer designation that is Latinized from υ Carinae, and abbreviated Upsilon Car or υ Car. This pair is part of the Diamond Cross asterism in southern Carina. The Upsilon Carinae system has a combined apparent magnitude of +2.97 and is approximately 1,400 light years (440 parsecs) from Earth. It is drifting further away with a line of sight velocity of +14 km/s.

In Chinese, 海石 (Hǎi Dàn), meaning Sea Rock, refers to an asterism consisting of υ Carinae, ε Carinae, ι Carinae, HD 83183 and HD 84810. Consequently, υ Carinae itself is known as 海石五 (Hǎi Dàn wǔ, .)

In the next 7500 years, the south Celestial pole will pass close to these stars and Iota Carinae (8100 CE).

Properties

The primary component, υ Carinae A, has a stellar classification of A8 Ib, making it a supergiant star that has exhausted the hydrogen at its core and evolved away from its brief main sequence lifetime as an B-type star. With an apparent magnitude of +3.08, it has an effective temperature of about 7,500 K, giving it a white hue. The companion, υ Carinae B, is a giant star with a classification of B7 III, although Mandrini and Niemela (1986) suggested it may be a subgiant star with a classification of B4–5 IV. The outer envelope of this star has an effective temperature of around 23,000 K, resulting in the blue-white hue of a B-type star.

The two stars have an angular separation of 5.030 arcseconds. As a binary star system, they would have an estimated orbital period of at least 19,500 years and a present-day separation of around 2,000 Astronomical Units. This system is roughly 12 million years old.

References

References

1. {{in lang. zh ''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.
2. {{in lang. zh [http://aeea.nmns.edu.tw/2006/0607/ap060728.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 28 日] {{Webarchive. link. (2013-05-13)
3. "Precession".
4. van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
5. (October 2017). "Discovery of magnetic A supergiants: the descendants of magnetic main-sequence B stars". Monthly Notices of the Royal Astronomical Society.
6. Samedov, Z. A.. (1988). "On the visual binary υ Car and the chemical composition of its brighter component". Izvestiya Krymskoj Astronomicheskoj Observatorii.
7. (November 1986). "On the visual binary Upsilon Carinae". Monthly Notices of the Royal Astronomical Society.
8. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society.
9. Nicolet, B.. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System". Astronomy and Astrophysics Supplement Series.
10. "CCDM J09471-6504AB -- Double or multiple star". Centre de Données astronomiques de Strasbourg.

::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. ::