Alpha Ceti

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Red giant star in the constellation Cetus

title: "Alpha Ceti" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["m-type-giants", "asymptotic-giant-branch-stars", "cetus", "bayer-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects", "stars-with-proper-names"] description: "Red giant star in the constellation Cetus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Alpha_Ceti" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Red giant star in the constellation Cetus ::

| name = α Ceti | image= |image=Cetus constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=12|mark_link=α Ceti |x=124|y=200 |caption=Location of α Ceti (circled) | epoch = J2000 | constell = Cetus | ra = | dec = | appmag_v = 2.53 | type = AGB | class = M1.5 IIIa | b-v = +1.64 | u-b = +1.93 | variable = | radial_v = | prop_mo_ra = | prop_mo_dec = | parallax = 13.09 | p_error = 0.44 | parallax_footnote = | absmag_bol = | mass = ; 1.465–1.933 | radius = | luminosity = | temperature = | metal_fe = | gravity = | rotational_velocity = 6.9 | age = | names = Menkar, 92 Ceti, HR 911, BD+03°419, HD 18884, SAO 110920, FK5 107, HIP 14135 | Simbad = Menkar Alpha Ceti (α Ceti, abbreviated Alpha Cet, α Cet), officially named Menkar ,{{cite book |last1=Kunitzsch |first1=Paul |last2=Smart |first2=Tim |date = 2006 |edition = 2nd rev. |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations |publisher = Sky Pub |location = Cambridge, Massachusetts |isbn = 978-1-931559-44-7

Nomenclature

Alpha Ceti is the star's Bayer designation. It has the traditional name Menkar, deriving from the Arabic word منخر manħar "nostril" (of Cetus). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Menkar for this star.

This star, along with γ Cet (Kaffaljidhma), δ Cet, λ Cet (also Menkar), μ Cet, ξ1 Cet and ξ2 Cet were Al Kaff al Jidhmah, "the Part of a Hand".

In Chinese, 天囷 (Tiān Qūn), meaning Circular Celestial Granary, refers to an asterism consisting of α Ceti, κ1 Ceti, λ Ceti, μ Ceti, ξ1 Ceti, ξ2 Ceti, ν Ceti, γ Ceti, δ Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for α Ceti itself is 天囷一 (Tiān Qūn yī, .)

Characteristics

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/fb/AlphaCetLightCurve.png" caption="A [[light curve]] for Alpha Ceti, plotted from ''[[Hipparcos]]'' data, folded with the period derived by Koen and Eyer (2002)"] ::

Despite having the Bayer designation α Ceti, at visual magnitude 2.54 this star is actually not the brightest star in the constellation Cetus. That honor goes instead to Beta Ceti at magnitude 2.04. Menkar is a red giant with a stellar classification of M1.5 IIIa. It has more than twice the mass of the Sun and, as a giant star, has expanded to about 100 times the Sun's radius. The large area of the photosphere means that it is emitting about 1,765 times as much energy as the Sun, even though the effective temperature is only (compared to on the Sun). The relatively low temperature gives Menkar the red hue of an M-type star.

Menkar has evolved from the main sequence after exhausting the hydrogen at its core. It has also exhausted its core helium, becoming an asymptotic giant branch star, and will probably become a highly unstable star like Mira before finally shedding its outer layers and forming a planetary nebula, leaving a relatively large white dwarf remnant. It has been observed to periodically vary in brightness, but only with an amplitude of about one hundredth of a magnitude.

Namesakes

Menkar (AK-123) was a United States Navy Crater class cargo ship named after the star.

References

"IAU Catalog of Star Names".
"IAU Working Group on Star Names (WGSN)".
"Bulletin of the IAU Working Group on Star Names, No. 1".
[https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cetus*.html Star Name - R.H. Allen p.160]
{{in lang. zh [http://aeea.nmns.edu.tw/2006/0607/ap060711.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日] {{Webarchive. link. (2012-02-04)
(1992). "Asymptotic giant branch stars near the sun". The Astronomical Journal.
(2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society.
van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
(January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics.
(January 2008). "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity". The Astronomical Journal.
(1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory.
(October 2008). "Cool luminous stars: the hybrid nature of their infrared spectra". Astronomy and Astrophysics.
(December 2006). "Tests of stellar model atmospheres by optical interferometry. IV. VINCI interferometry and UVES spectroscopy of Menkar". Astronomy and Astrophysics.
"MENKAR (Alpha Ceti)". [[University of Illinois]].
(2024-02-01). "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version". Astronomy and Astrophysics.
(December 21, 2004). "The Colour of Stars". [[Commonwealth Scientific and Industrial Research Organisation]].

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