Eta Capricorni is a binary star

Binary star

A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...

 in the constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 Capricornus

Capricornus

Capricornus is one of the constellations of the zodiac; it is often called Capricorn, especially when referring to the corresponding astrological sign. Its name is Latin for "horned male goat" or "goat horn", and it is commonly represented in the form of a sea-goat: a mythical creature that is half...

. It also has the traditional star name Arm. It is approximately 158 light years from Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.

The primary component, η Capricorni A, is a white A-type

Stellar classification

In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

 main sequence dwarf

Main sequence

The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...

 with an apparent magnitude

Apparent magnitude

The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 of +4.82. Its companion, η Capricorni B, has an apparent magnitude of +6.5 and is located 0.34 arcseconds from the primary.

Sometimes, this star is called by the name Armus.

Chinese Name

In Chinese

Chinese language

The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...

, , meaning Twelve States

Girl (Chinese constellation)

The Girl mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise.- Asterisms :...

, refers to an asterism which is represent twelve ancient states in the Spring and Autumn Period and the Warring States Period

Warring States Period

The Warring States Period , also known as the Era of Warring States, or the Warring Kingdoms period, covers the Iron Age period from about 475 BC to the reunification of China under the Qin Dynasty in 221 BC...

, consisting of η Capricorni, φ Capricorni

Phi Capricorni

Phi Capricorni is a star in the constellation Capricornus. φ Capricorni is an orange K-type bright giant with an apparent magnitude of +5.17...

, ι Capricorni

Iota Capricorni

Iota Capricorni is a star in the constellation Capricornus.ι Capricorni is a yellow G-type giant with a mean apparent magnitude of +4.28. It is approximately 216 light years from Earth...

, 38 Capricorni, 35 Capricorni, 36 Capricorni

36 Capricorni

36 Capricorni is a star in the constellation Capricornus. 36 Capricorni is a yellow G-type giant with an apparent magnitude of +4.50. It is approximately 179 light years from Earth.-Chinese Name:...

, χ Capricorni

Chi Capricorni

Chi Capricorni is a star in the constellation Capricornus. χ Capricorni is a white A-type main sequence dwarf with an apparent magnitude of +5.30...

, θ Capricorni

Theta Capricorni

Theta Capricorni is a star in the constellation Capricornus. θ Capricorni is a white A-type main sequence dwarf with an apparent magnitude of +4.08...

, 30 Capricorni, 33 Capricorni, ζ Capricorni

Zeta Capricorni

Zeta Capricorni, , is a fourth-magnitude star in the constellation Capricornus. ζ Capricorni is a binary star, with the primary component ζ Capricorni A being a yellow G-type supergiant with an apparent magnitude of +3.77...

, 19 Capricorni, 26 Capricorni, 27 Capricorni, 20 Capricorni and 21 Capricorni. . Consequently, η Capricorni itself is known as , meaning that this star (together with 21 Capricorni and β Serpentis

Beta Serpentis

Beta Serpentis is a star system in the constellation Serpens, in its head . It was a member of indigenous Arabic asterism al-Nasaq al-Sha'āmī, "the Northern Line" of al-Nasaqān "the Two Lines", along with β Her , γ Her and γ Ser .According to the catalogue of stars in the Technical Memorandum...

 in Right Wall of Heavenly Market Enclosure

Heavenly Market enclosure

Tian Shi Yuan, the Heavenly Market Enclosure , is one of the San Yuan or Three enclosures. Stars and constellations of this group are visible during late summer and early autumn in the Northern Hemisphere . The summer triangle lies directly to the northwest.-Asterisms:The asterisms are :...

(asterism)) represent Zhou

Zhou Dynasty

The Zhou Dynasty was a Chinese dynasty that followed the Shang Dynasty and preceded the Qin Dynasty. Although the Zhou Dynasty lasted longer than any other dynasty in Chinese history, the actual political and military control of China by the Ji family lasted only until 771 BC, a period known as...

(possibly Chow, the dynasty in China).