9 Cephei (9 Cep), also known as V337 Cephei, is a

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Cepheus. It is visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

In 1967, Graham Hill announced his discovery that 9 Cephei is a variable star. 9 Cephei was given the name V337 Cephei and classified as an α Cygni variable in 1979. It varies irregularly between magnitude 4.69 and 4.78. A study of the Hipparcos satellite photometry showed an amplitude of 0.56 magnitudes, but could find no periodicity. 9 Cephei is considered to be a member of the Cepheus OB2 stellar association, a scattering of massive bright stars around a thousand parsecs away in the southern part of the constellation Cepheus. Calculations of the physical properties of 9 Cephei vary considerably even from broadly similar observational data. Modelling using the non-LTE line-blanketed CMFGEN atmospheric code gives a temperature of 18,000 K, radius of , luminosity of , and mass of . Calculations using the FASTWIND model give gives a temperature of 19,200 K, radius of , luminosity of , and mass of .

References

{{DEFAULTSORT:9 Cephei Cepheus (constellation) B-type supergiants Cephei, 09 Alpha Cygni variables 106801 Cephei, V337 8279 206165 BD+61 2169 J21375521+6204548 IRAS catalogue objects