Gamma Ceti (γ Ceti, abbreviated Gamma Cet, γ Cet) is a

triple star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a ''star cluster'' or ''galaxy'', although, broadly speaking, ...

in the

equatorial Equatorial may refer to something related to: *Earth's equator **the tropics, the Earth's equatorial region **tropical climate *the Celestial equator ** equatorial orbit **equatorial coordinate system ** equatorial mount, of telescopes * equatorial ...

constellation of

Cetus Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellat ...

. It has a combined

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 3.47. Based upon parallax measurements, this star is located at a distance of about 80 light-years (24.4

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

s) from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. The three components are designated Gamma Ceti A (officially named Kaffaljidhma , the traditional name for the entire system), B and C.

Nomenclature

''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 A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a ''star cluster'' or ''galaxy'', although, broadly speaking, ...

(WMC) for multiple star systems, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

(IAU). 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 The ''Gliese Catalogue of Nearby Stars'' (, English ) is a star catalogue listing stars located within 25 parsecs (81.54 ly) of the Sun. First edition and supplements In 1957 German astronomer Wilhelm Gliese published his first star catalogue ...

. Gamma Ceti bore the traditional names of or , derived from ar, الكف الجذماء, rtl=yes ('the cut-short hand'). According to a 1971

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

memorandum, was originally the title for five stars: Gamma Ceti as , Xi¹ Ceti as , Xi² Ceti as , Delta Ceti as and Mu Ceti as (excluding Alpha Ceti and Lambda Ceti). The IAU Working Group on Star Names (WGSN) approved the name ''Kaffaljidhma'' for the component Gamma Ceti A on February 1, 2017. In

Chinese astronomy Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twe ...

, , 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 ν Ceti, Latinized as Nu Ceti, is a binary star system in the equatorial constellation of Cetus. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.86. The system is located approxim ...

, Delta Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are ofte ...

for Gamma Ceti itself is ('the Eighth Star of Circular Celestial Granary').

Triple system

Gamma Ceti appears to be a

. 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 An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...

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 An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables VI ...

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, 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 In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

with the designation . It shares a

common proper motion This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outsid ...

with A and is at a very similar distance, but is separated from the close pair by over . It has a

spectral classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

of K5V. There are several other stars brighter and closer to Gamma Ceti than – , HD 16985, and – but they are all more distant background stars.

Properties

The measured

angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...

of the primary star is . At the estimated distance of this system, this yields a physical size of about 1.9 times the

radius of the Sun Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3: :1\,R_ = 6.957\t ...

. The secondary component of this system is an X-ray source with a luminosity of . 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.

References

External links

Information about Kaffaljidhma on STARS

Gamma Ceti on AAS WorldWide Telescope
{{DEFAULTSORT:Gamma Ceti Cetus (constellation) Ceti, Gamma Kaffaljidhma Ceti, 86 A-type main-sequence stars F-type main-sequence stars K-type main-sequence stars 012706 016970 0804 Durchmusterung objects