Theta Cephei is a Class A7

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...

, fourth-magnitude star

Star

A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

 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....

 Cepheus

Cepheus (constellation)

Cepheus is a constellation in the northern sky. It is named after Cepheus, King of Aethiopia in Greek mythology. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations.-Stars:...

. Theta Cephei is a white spectroscopic binary star, located about 135 light-year

Light-year

A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s 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...

. Shared with η Cep

Eta Cephei

Eta Cephei is a class K0 third-magnitude giant star in the constellation Cepheus. Eta Cephei is an orange giant star with a very high proper motion on the celestial sphere. It is about 45 light-years from Earth...

, this star have the title Al Kidr, meaning unknown

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 Celestial Hook

Rooftop (Chinese constellation)

The Rooftop 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 consisting of 4 Cephei, HD 194298, η Cephei

Eta Cephei

Eta Cephei is a class K0 third-magnitude giant star in the constellation Cepheus. Eta Cephei is an orange giant star with a very high proper motion on the celestial sphere. It is about 45 light-years from Earth...

, α Cephei

Alpha Cephei

Alpha Cephei is a second magnitude star in the constellation of Cepheus that is relatively close to Earth at only 49 light years...

, ξ Cephei

Xi Cephei

Xi Cephei is a star in the constellation Cepheus. It has the traditional name Kurhah or Alkirdah or Al Kirduh, and the name was from Al Ḳurḥaḥ , an Arabic word that translated as a white spot, or blaze, in the face of a horse and other suggestion was Al Ḳirdah , the Ape.Xi Cephei belongs to...

, 26 Cephei, ι Cephei

Iota Cephei

Iota Cephei is a Class K0, third-magnitude star in the constellation Cepheus. Iota Cephei is an orange giant star located about 115 light-years from Earth. Due to precession of the equinoxes, it will become the pole star some time around 5200 CE.-External links:...

 and ο Cephei

Omicron Cephei

Omicron Cephei is a binary star in the constellation of Cepheus. It consists of a less massive K-type main sequence star in orbit with a more massive G-type giant star. The overall apparent visual magnitude of the system is 4.75.The pair was first determined to be binary by F. G. W. Struve...

. Consequently, θ Cephei itself is known as .