|Observation data (Epoch J2000)|
|Right ascension||02h 22m 36.2s|
|Declination||+86° 19′ 08″|
|Distance||~ 740 Mpc|
|Apparent magnitude (V)||18.95|
|LEDA 2832137 , 3C 61.1, 8C 0210+860|
|See also: Quasar, List of quasars|
Epsilon Cephei, Latinized from ε Cephei, is a star in the northern constellation of Cepheus. Based upon an annual parallax shift of 38.17 mas as seen from the Earth, it is located about 85 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 4.18.This is a yellow-white hued, F-type star with a stellar classification of F0 V (Sr II) or F0 IV. Thus it may either be an F-type main sequence star showing an abundance excess of strontium, or it could be a more evolved subgiant star. It is a Delta Scuti variable star that cycles between magnitudes 4.15 and 4.21 every 59.388 minutes. The star displays an infrared excess, indicating the presence of a debris disk with a temperature of 65 K orbiting at a radius of 62 AU. This dust has a combined mass equal to 6.6% of the Earth's mass.There is a faint companion star at an angular separation of 330±50 mas along a position angle of 90°±10°. This corresponds to a projected physical separation of 8.6±1.4 AU. The probability of a random star being situated this close to Epsilon Cephei is about one in a million, so it is most likely physically associated. If so, then the debris disk is probably circumbinary. The fact that this companion was not detected during the Hipparcos mission may indicate its orbit has a high eccentricity. The companion star has a K-band magnitude of 7.8 and is probably of class K8–M2.Iota Cephei
Iota Cephei (ι Cephei, ι Cep) is a solitary star in the northern constellation Cepheus. Based upon an annual parallax shift of 15.83 mas as seen from the Earth, it is located about 206 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 3.5.This is a K-type giant star with a stellar classification of K0 III. It is currently at an evolutionary stage known as a red clump, indicating that it is generating energy through the fusion of helium at its core. This star has 11 times the Sun's radius and about 2.15 times the mass of the Sun. It is emitting 57 times as much luminosity as the Sun, which is being radiated from its photosphere at an effective temperature of 4,768 K.Rho1 Cephei
Rho1 Cephei (ρ1 Cephei) is a double star located in the northern constellation of Cepheus. As of 2014, the pair had an angular separation of 0.29 arc seconds along a position angle of 211.1°. This corresponds to a projected separation of 18.1 AU. Rho1 Cephei is faintly visible to the naked eye with an apparent visual magnitude of 5.84, and it forms an optical pair with the brighter star Rho2 Cephei. Based upon an annual parallax shift of 15.83 mas as seen from the Earth, Rho1 Cephei is located about 206 light years from the Sun.
The primary component is a chemically peculiar Am star with a stellar classification of A2m. It has twice the mass of the Sun and is around 320 million years old. The smaller companion may be the source of the X-ray emission from this location, as stars similar to the primary component do not generally produce detectable levels of X-rays.Rho2 Cephei
Rho2 Cephei, Latinized from ρ2 Cephei, or simply ρ Cephei, is a solitary star in the northern constellation of Cepheus. With an apparent visual magnitude of 5.50, it is faintly visible to the naked eye, forming an optical pair with Rho1 Cephei. Based upon an annual parallax shift of 13.31 mas as seen from the Earth, it is located about 245 light years from the Sun.
Rho2 Cephei is an A-type main sequence star with a stellar classification of A3 V, estimated to be 85 million years old. It has a high rate of rotation, showing a projected rotational velocity of 133 km/s. The effective temperature of its photosphere is 8,511 K and its bolometric luminosity, the total amount of radiation it emits at all wavelengths, is 32 L☉.Theta Cephei
Theta Cephei, Latinized from θ Cephei, is a stellar class A7, fourth-magnitude star in the constellation Cepheus. It is a white-hued, single-lined spectroscopic binary system, located about 206 light-years from Earth. The pair have an orbital period of 840.6 days with a low eccentricity of 0.03. Shared with η Cep, this star system has the title Al Kidr.In Chinese, 天鈎 (Tiān Gōu), meaning Celestial Hook, refers to an asterism consisting of 4 Cephei, HD 194298, η Cephei, α Cephei, ξ Cephei, 26 Cephei, ι Cephei and ο Cephei. Consequently, θ Cephei itself is known as 天鈎三 (Tiān Gōu sān, English: the Third Star of Celestial Hook.).