Gamma Ceti

γ Ceti (Latinised to Gamma Ceti) is the system's Bayer designation. The designations of the three components as Gamma Ceti A, B and C derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).{{cite arXiv|title=On the naming convention used for multiple star systems and extrasolar planets|date=3 December 2010|eprint=1012.0707|class=astro-ph.SR|last1=Hessman|first1=F. V.|last2=Dhillon|first2=V. S.|last3=Winget|first3=D. E.|last4=Schreiber|first4=M. R.|last5=Horne|first5=K.|last6=Marsh|first6=T. R.|last7=Guenther|first7=E.|last8=Schwope|first8=A.|last9=Heber|first9=U.}} The close pair AB is also designated HIP 12706, HD 16970, and HR 804. The system of A, B, and C is collectively designated GJ 106.1 in the Gliese Catalogue of Nearby Stars.

Gamma Ceti bore the traditional names of {{lang|ar-Latn|Al Kaff al Jidhmah}} or {{lang|ar-Latn|Kaffaljidhma}}, derived from {{langx|ar|الكف الجذماء|rtl=yes}} {{lang|ar-Latn|al-kaf al-jaðmāʾ}} ('the cut-short hand'). According to a 1971 NASA memorandum, {{lang|ar-Latn|Al Kaff al Jidhmah}} was originally the title for five stars: Gamma Ceti as {{lang|ar-Latn|Kafaljidma}}, Xi¹ Ceti as {{lang|ar-Latn|Al Kaff al Jidhmah I}}, Xi² Ceti as {{lang|ar-Latn|Al Kaff al Jidhmah II}}, Delta Ceti as {{lang|ar-Latn|Al Kaff al Jidhmah III}} and Mu Ceti as {{lang|ar-Latn|Al Kaff al Jidhmah IV}} (excluding Alpha Ceti and Lambda Ceti). The IAU Working Group on Star Names (WGSN){{Cite web|url=https://www.iau.org/science/scientific_bodies/working_groups/280/|title=Division C WG Star Names|publisher=International Astronomical Union|access-date=2017-04-01|url-status=live|archive-url=https://web.archive.org/web/20170802000632/https://www.iau.org/science/scientific_bodies/working_groups/280/|archive-date=2017-08-02}} approved the name Kaffaljidhma for the component Gamma Ceti A on February 1, 2017.

In Chinese astronomy, {{lang|zh|天囷}} {{lang|zh-Latn|Tiān Qūn}}, meaning 'Circular Celestial Granary', refers to an asterism consisting of Gamma Ceti, Alpha Ceti, Kappa¹ Ceti, Lambda Ceti, Mu Ceti, Xi¹ Ceti, Xi² Ceti, Nu Ceti, Delta Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for Gamma Ceti itself is {{lang|zh|天囷八}} {{lang|zh-Latn|Tiān Qūn bā}} ('the Eighth Star of Circular Celestial Granary').{{cite web|url=http://aeea.nmns.edu.tw/2006/0607/ap060711.html|title=中國古代的星象系統 (72): 胃宿天區|author1=陳冠中|author2=陳輝樺|website=AEEA 天文教育資訊網|trans-website=AEEA (Activities of Exhibition and Education in Astronomy)|date=11 July 2006|publisher=National Museum of Natural Science|language=zh|url-status=live|archive-url=https://web.archive.org/web/20201002232819/http://aeea.nmns.edu.tw/2006/0607/ap060711.html|archive-date=2020-10-02}}

Gamma Ceti appears to be a triple star system.{{cite web|url=http://ad.usno.navy.mil/wds/|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|title=Washington Double Star Catalog|publisher=United States Naval Observatory|date=2 October 2008|access-date=2 January 2018|archive-url=https://web.archive.org/web/20110214155533/http://ad.usno.navy.mil/wds/|archive-date=14 February 2011|url-status=dead}} The inner pair (A and B) have an angular separation of 2.6 arcseconds. The primary component of this pair (A) is an A-type main sequence star with a stellar classification of A3 V and a visual magnitude of 3.6. The fainter secondary component (B) is an F-type main sequence star that has a classification of F3 V and a magnitude of 6.6. The contrasting colors of these two stars makes them a popular target of amateur astronomers. The two can be resolved with a small, {{Convert|4|in|cm|abbr=on}} aperture telescope under ideal seeing conditions, although at times they can be a challenge to resolve even with a much larger scope.

At a wide separation of 840 arcseconds is component C, a dim, magnitude 10.2 K-type star with the designation {{nowrap|BD+02 418}}. It shares a common proper motion with A and is at a very similar distance, but is separated from the close pair by over {{val|20,000|ul=au|fmt=commas}}. It has a spectral classification of K5V. There are several other stars brighter and closer to Gamma Ceti than {{nowrap|BD+02 418}} – {{nowrap|BD+02 419}}, HD 16985, and {{nowrap|TYC 50-1274-1}} – but they are all more distant background stars.

The measured angular diameter of the primary star is {{nowrap|0.74 ± 0.08 mas}}. At the estimated distance of this system, this yields a physical size of about 1.9 times the radius of the Sun. The secondary component of this system is an X-ray source with a luminosity of {{nowrap|2.2 × 10²⁹ erg s⁻¹}}. Gamma Ceti is about 300 million years old, and it appears to be a member of the stream of stars loosely associated with the Ursa Major Moving Group. The primary has been examined for an excess of infrared emission that would suggest the presence of circumstellar matter, but none was found.

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The radius (R_*) is given by:

:$\backslash begin\{align\}\; 2\backslash cdot\; R\_*$

& = \frac{(24.4\cdot 0.74\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\

& \approx 3.88\cdot R_{\bigodot}

\end{align}

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}}

• [http://stars.astro.illinois.edu/sow/kaffaljidhma.html Information about Kaffaljidhma on STARS]
• [http://worldwidetelescope.org/webclient/#/place=20.739&ra=2.72170&dec=3.23580&fov=0.23438 Gamma Ceti on AAS WorldWide Telescope]

{{Stars of Cetus}}

{{DEFAULTSORT:Gamma Ceti}}

Category:Cetus

Ceti, Gamma

Kaffaljidhma

Ceti, 86

Category:A-type main-sequence stars

Category:F-type main-sequence stars

Category:K-type main-sequence stars

012706

016970

0804

Category:Durchmusterung objects