Alpha Ceti
Red giant star in the constellation Cetus
Alpha Ceti (α Ceti , abbreviated Alpha Cet , α Cet ), officially named Menkar ,[ 9] [ 10] is the second-brightest star in the constellation of Cetus . It is a cool luminous red giant estimated to be about 250 light years away based on parallax .
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)[ 11] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[ 12] 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".[ 13]
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 , English: the First Star of Circular Celestial Granary .)[ 14]
Characteristics
A light curve for Alpha Ceti, plotted from Hipparcos data,[ 15] folded with the period derived by Koen and Eyer (2002)[ 16]
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.[ 4] It has more than twice the mass of the Sun [ 6] and, as a giant star , has expanded to about 100 times the Sun's radius .[ 7] 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 3,738 K (compared to 5,778 K on the Sun ).[ 7] The relatively low temperature gives Menkar the red hue of an M-type star.[ 17]
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 ,[ 3] 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.[ 18] It has been observed to periodically vary in brightness, but only with an amplitude of about one hundredth of a magnitude.[ 16]
Namesakes
Menkar (AK-123) was a United States Navy Crater class cargo ship named after the star.
References
^ a b c d e 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
^ a b c 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
^ a b Eggen, Olin J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal , 104 : 275, Bibcode :1992AJ....104..275E , doi :10.1086/116239
^ a b c Tsuji, T. (October 2008), "Cool luminous stars: the hybrid nature of their infrared spectra", Astronomy and Astrophysics , 489 (3): 1271–1289, arXiv :0807.4387 , Bibcode :2008A&A...489.1271T , doi :10.1051/0004-6361:200809869 , S2CID 19007399
^ Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics , 430 (1): 165–186, arXiv :astro-ph/0409579 , Bibcode :2005A&A...430..165F , doi :10.1051/0004-6361:20041272 , S2CID 17804304
^ a b Wittkowski, M.; et al. (December 2006), "Tests of stellar model atmospheres by optical interferometry. IV. VINCI interferometry and UVES spectroscopy of Menkar", Astronomy and Astrophysics , 460 (3): 855–864, arXiv :astro-ph/0610150 , Bibcode :2006A&A...460..855W , doi :10.1051/0004-6361:20066032 , S2CID 16525827
^ a b c d e f g h Soubiran, C.; Creevey, O. L.; Lagarde, N.; Brouillet, N.; Jofré, P.; Casamiquela, L.; Heiter, U.; Aguilera-Gómez, C.; Vitali, S.; Worley, C.; de Brito Silva, D. (2024-02-01). "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version" . Astronomy and Astrophysics . 682 : A145. arXiv :2310.11302 . Bibcode :2024A&A...682A.145S . doi :10.1051/0004-6361/202347136 . ISSN 0004-6361 . Menkar's database entry at VizieR .
^ Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal , 135 (1): 209–231, Bibcode :2008AJ....135..209M , doi :10.1088/0004-6256/135/1/209 , S2CID 121883397
^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7 .
^ "IAU Catalog of Star Names" . Retrieved 28 July 2016 .
^ "IAU Working Group on Star Names (WGSN)" . Retrieved 22 May 2016 .
^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF) . Retrieved 28 July 2016 .
^ Star Name - R.H. Allen p.160
^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日 Archived 2012-02-04 at the Wayback Machine
^ "/ftp/cats/more/HIP/cdroms/cats" . Centre de Données astronomiques de Strasbourg . Strasbourg astronomical Data Center. Retrieved 15 October 2022 .
^ a b Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society , 331 (1): 45, arXiv :astro-ph/0112194 , Bibcode :2002MNRAS.331...45K , doi :10.1046/j.1365-8711.2002.05150.x
^ "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
^ Kaler, James B., "MENKAR (Alpha Ceti)" , Stars , University of Illinois , retrieved 2011-12-24
External links