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DH Cephei, HD215835, HIP112470

DH Cephei is a blue rotating star that can be located in the constellation of Cepheus. The star can not be seen by the naked eye, you need a telescope to see it.

HIP112470 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD215835.

DH Cephei has alternative name(s), DH Cep.

Location of DH 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 DH Cephei, the location is 22h 46m 54.11 and +58 d 05` 03.6 .

Proper Motion of DH Cephei

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -2.39 ± 0.63 miliarcseconds/year towards the north and -1.77 ± 0.87 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is -33.40000 km/s with an error of about 3.20 km/s .

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

DH Cephei has a spectral type of O5.5. This means the star is a blue star. The star has a B-V Colour Index of 0.33 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,656 Kelvin. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

DH Cephei Apparent and Absolute Magnitudes

DH Cephei has an apparent magnitude of 8.59 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 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.35. 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 DH Cephei

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -1.00 which gave the calculated distance to DH Cephei as -3261.63 light years away from Earth or -1000 parsecs. It would take a spaceship travelling at the speed of light, -3261.63 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 0.65 which put DH Cephei at a distance of 5017.90 light years or 1538.46 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Variable Type of DH Cephei

The star is a rotating Rotating ellipsoidal 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. DH Cephei brightness ranges from a magnitude of 8.698 to a magnitude of 8.645 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 2.1 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.

DH Cephei Facts

Alternative Names

Traditional/Proper NameDH Cephei
Short NameDH Cep
Hipparcos Library I.D.112470
Bonner DurchmusterungBD+57 2607
Henry Draper Designation215835

Visual Facts

Star Type star
Visual / Apparent Magnitude8.59
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)22h 46m 54.11
Declination (Dec.)+58 d 05` 03.6
Galactic Latitude-0.90 degrees
Galactic Longitude107.07 degrees
1997 Distance from Earth-1.00 Parallax (milliarcseconds)
 -3261.63 Light Years
 -1000 Parsecs
2007 Revised Distance from Earth0.65 Parallax (milliarcseconds)
 5017.90 Light Years
 1538.46 Parsecs
Proper Motion Dec.-2.39 ± 0.63 milliarcseconds/year
Proper Motion RA.-1.77 ± 0.87 milliarcseconds/year
B-V Index0.33
Radial Velocity-33.40 ± 3.20 km/s
Spectral TypeO5.5
Colour(O) blue

Variable Star Details

Variable Star ClassRotating
Variable Star TypeRotating ellipsoidal
Mean Variability Period in Days2.111
Variable Magnitude Range (Brighter - Dimmer)8.645 - 8.698

Estimated Facts

Calculated Effective Temperature6,656 Kelvin

Sources and Links

SIMBAD SourceLink

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