Universe Guide


9 Cephei, HD206165, HIP106801

9 Cephei is a blue pulsating very luminous supergiant star that can be located in the constellation of Cepheus. 9 Cephei is the brightest star in Cepheus based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP106801 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD206165.

9 Cephei has alternative name(s), V337 Cep.

Location of 9 Cephei

The location of the star in the galaxy is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For 9 Cephei, the location is 21h 37m 55.23 and +62d04`55.0 .

9 Cephei Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 220000.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of 9 Cephei

9 Cephei has a spectral type of B2Ib. This means the star is a blue supergiant star. The star has a B-V Colour Index of 0.24 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,120 Kelvin.

9 Cephei Radius has been calculated as being 95.06 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 66,143,360.69.km. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.28 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

9 Cephei Apparent and Absolute Magnitudes

9 Cephei has an apparent magnitude of 4.76 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of -5.95 Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to 9 Cephei

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.72 which gave the calculated distance to 9 Cephei as 4530.05 light years away from Earth or 1388.89 parsecs. It would take a spaceship travelling at the speed of light, 4530.05 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

Variable Type of 9 Cephei

The star is a pulsating Alpha Cygnus variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. 9 Cephei brightness ranges from a magnitude of 4.874 to a magnitude of 4.821 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 days (variability).

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

9 Cephei Facts

Alternative Names

Traditional/Proper Name9 Cephei
Flamsteed Name9 Cephei
Flamsteed Short Name9 Cep
Short NameV337 Cep
Hipparcos Library I.D.106801
Bonner DurchmusterungBD+61 2169
Henry Draper Designation206165

Visual Facts

Star Typesupergiant star
Visual / Apparent Magnitude4.76
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 37m 55.23
Declination (Dec.)+62d04`55.0
Galactic Latitude7.25 degrees
Galactic Longitude102.27 degrees
1997 Distance from Earth0.72 Parallax (milliarcseconds)
 4530.05 Light Years
 1388.89 Parsecs
B-V Index0.24
Radial Velocity-13.50 ± 0.80 km/s
Iron Abundance-0.28 ± 9.99 Fe/H
Spectral TypeB2Ib
Colour(B) blue

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeAlpha Cygnus
Mean Variability Period in Days0.050
Variable Magnitude Range (Brighter - Dimmer)4.821 - 4.874

Estimated Facts

Luminosity (x the Sun)220,000.0000000
Calculated Effective Temperature7,120 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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