Mu Ceti (μ Ceti) is a

binary star A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Cetus Cetus () is a constellation, sometimes called 'the whale' in English. The Cetus (mythology), 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- ...

, the whale, close to

Pisces Pisces may refer to: *Pisces (astrology), an astrological sign Astronomy *Pisces (constellation), a constellation ** Pisces Overdensity, an overdensity of stars in the Milky Way's halo that is situated in the Pisces constellation ** Pisces II, a ...

. The combined

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of the system is +4.27, making it visible as a faint star from skies with low or no luminous pollution. Based upon

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements taken by the Gaia spacecraft, it is located 87

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s away. The location of Mu Ceti next to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

make it succeptible to lunar occultations.

Nomenclature

Mu Ceti is the system's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

. It has no official proper name. In Chinese, (), 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 Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for Mu Ceti itself is "the Fourth Star of Circular Celestial Granary".AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日

Characteristics

Mu Ceti is a

spectroscopic binary A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

. These systems have binarity inferred from variations in their

spectral line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission (electromagnetic radiation), emission or absorption (electromagnetic radiation), absorption of light in a narrow frequency ...

s, which shift from redder to bluer (

gravitational redshift In physics and general relativity, gravitational redshift (known as Einstein shift in older literature) is the phenomenon that electromagnetic waves or photons travelling out of a gravitational well lose energy. This loss of energy correspo ...

) across the orbit. It has also been resolved by

speckle interferometry Speckle imaging comprises a range of high-resolution Astrophotography, astronomical imaging techniques based on the analysis of large numbers of short Exposure (photography), exposures that freeze the variation of Astronomical seeing, atmospheri ...

. The energy output is dominated by the main star, which is 25 times brighter than the companion. They share a highly

eccentric orbit In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless quantity, dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circu ...

, are viewed orbiting nearly edge-on, and take 34 years to complete an orbit. The main component (

4.30) has an

spectral class 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 ...

A9IIIp, suggesting it is a late-type

giant star A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...

and is chemically peculiar. Its physical properties, however, do not support this evolutionary stage and the peculiar class, Mu Ceti is instead in the late

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

, about to become a

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

. This star is 67% more massive than the Sun and two times larger. Its

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

is , giving it the white hue typical of late A/early F stars. It has been suspected to be a

δ Scuti variable A Delta Scuti variable (sometimes termed dwarf cepheid when the V-band amplitude is larger than 0.3 mag.) is a class of pulsating star, comprising several sub-classes of object with A- or F-type spectra. The variables follow a period-luminosity ...

, and found to be of constant brightness by some studies, but a more recent analysis with the

Transiting Exoplanet Survey Satellite Transiting Exoplanet Survey Satellite (TESS) is a space telescope for NASA's Explorer program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission. It was launched on ...

confirm this star is a Gamma Doradus variable. The secondary (apparent magnitude 7.80) is a K0.5V star, indicating it is a

dwarf star A dwarf star is a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. The meaning of the word "dwarf" was later extended to some star-sized objects that are not stars, and compact stellar remnants that are ...

cooler than the Sun. Mu Ceti B has an

of and has a mass and radius measuring 80% solar units. Its effective temperature give it an orange hue typical of

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 ...

s. Three companions were all discovered during

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks f ...

s of Mu Ceti by the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

. An orbit was derived for the brightest with a period of 1,202 days. Later studies have failed to find any evidence of these companions.

Notes

References

{{DEFAULTSORT:Mu Ceti Cetus Cetus, Mu Cetus, Mu Ceti, 87 012828 0123 017094 Durchmusterung objects Gamma Doradus variables A-type main-sequence stars K-type main-sequence stars Spectroscopic binaries Binary stars