Mu Ceti

Did You Know?

• In Chinese, Mu Ceti is part of the Circular Celestial Granary asterism, which includes 13 stars.
• The Chinese name for Mu Ceti itself is 'the Fourth Star of Circular Celestial Granary'.
• Mu Ceti has no official proper name.

Characteristics

Mu Ceti is a spectroscopic binary, with binarity inferred from variations in its spectral lines that shift across the orbit due to gravitational redshift; it has also been resolved by speckle interferometry. The primary star dominates the energy output, being 25 times brighter than the companion. The two stars share a highly eccentric orbit viewed nearly edge-on and complete an orbit every 34 years. The main component, of apparent magnitude 4.30, has a spectral class of A9IIIp, suggesting a late-type giant and chemically peculiar star, but its physical properties do not support that classification; it is instead in the late main sequence, about to become a subgiant. It is 67% more massive than the Sun and twice as large, with an effective temperature giving it a white hue typical of late A/early F stars. Although suspected to be a δ Scuti variable and found constant by some studies, more recent TESS data confirm it is a Gamma Doradus variable. The secondary, apparent magnitude 7.80, is a K0.5V dwarf star cooler than the Sun, with an effective temperature, mass, and radius each about 80% of solar values, giving it an orange hue. Three companions were discovered during lunar occultations, and an orbit with a period of 1,202 days was derived for the brightest, but later studies have found no evidence of these companions.