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 with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

in the constellation Cepheus. 9 Cephei was given the name V337 Cephei and classified as an

α Cygni variable Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant stars of spectral types B or A. Variations in ...

in 1967. It varies irregularly between magnitude 4.69 and 4.78. A study of the Hipparcos satellite

photometry Photometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electro ...

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 Cepheus, V337 8279 206165 BD+61 2169 J21375521+6204548 IRAS catalogue objects