[ 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.[6]]This is a yellow-white hued, F-type star with a stellar classification of {{nowrap|F0 V (Sr II)}}[4] or F0 IV.[5] 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.[3] 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.[15]
There is a faint companion star at an angular separation of {{Val|330|50|u=mas}} along a position angle of {{Val|90|10|u=°}}. This corresponds to a projected physical separation of {{Val|8.6|1.4|u=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.[5]
Naming
In Chinese, {{lang|zh|螣蛇}} ({{lang|zh-Latn|Téng Shé}}), meaning Flying Serpent, refers to an asterism consisting of ε Cephei, α Lacertae, 4 Lacertae, π2 Cygni, π1 Cygni, HD 206267, β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, λ Andromedae, κ Andromedae, ι Andromedae, and ψ Andromedae. Consequently, ε Cephei itself is known as {{lang|zh|螣蛇九}} ({{lang|zh-Latn|Téng Shé jiǔ}}, {{lang-en|the Ninth Star of Flying Serpent}})[1]
References
1. ^{{zh icon}} AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日
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