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17 Comae Berenices B, 17 Comae Berenices, HD108662, HIP60904, HR4752

17 Comae Berenices B is a blue rotating variable star that can be located in the constellation of Coma Berenices. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

17 Comae Berenices B's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR4752. HIP60904 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD108662.

17 Comae Berenices B has alternative name(s) :- , AI Com.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 17 Comae Berenices with it shortened to 17 Com.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+26 2354.

More details on star alternative names can be found at Star Names .

Location of 17 Comae Berenices B

The location of the star in the night sky 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 17 Comae Berenices B, the location is 12h 28m 54.72 and +25° 54` 46.4 .

Proper Motion of 17 Comae Berenices B

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 -15.46 ± 0.17 miliarcseconds/year towards the north and -21.94 ± 0.25 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 -1.40000 km/s with an error of about 0.50 km/s .

17 Comae Berenices B 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 49.36 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of 17 Comae Berenices B

17 Comae Berenices B has a spectral type of A0p. This means the star is a blue variable star. The star is 7,405.00 Parsecs from the Galactic Centre or terms of Light Years is 24,152.40 s. The star has a B-V Colour Index of -0.05 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 11,775 Kelvin.

17 Comae Berenices B Radius has been calculated as being 1.63 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,130,990.94.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.43. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

17 Comae Berenices B Apparent and Absolute Magnitudes

17 Comae Berenices B has an apparent magnitude of 5.29 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 0.70 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.98. 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 17 Comae Berenices B

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 12.06 which gave the calculated distance to 17 Comae Berenices B as 270.45 light years away from Earth or 82.92 parsecs. It would take a spaceship travelling at the speed of light, 270.45 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 13.72 which put 17 Comae Berenices B at a distance of 237.73 light years or 72.89 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.

The star's Galacto-Centric Distance is 7,405.00 Parsecs or 24,152.40 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of 17 Comae Berenices B

The star is a rotating Alpha2 Canum Venaticorum 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. 17 Comae Berenices B brightness ranges from a magnitude of 5.253 to a magnitude of 5.231 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 5.1 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.

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17 Comae Berenices B Facts

Visual Facts


Primary / Proper / Traditional Name17 Comae Berenices B
Alternative NamesHD 108662, HIP 60904, HR 4752, 17 Comae Berenices, 17 Com, BD+26 2354, AI Com
Spectral TypeA0p
Multiple Star SystemYes
Star TypeVariable Star
Colour blue
GalaxyMilky Way
ConstellationComa Berenices
Absolute Magnitude0.70 / 0.98
Visual / Apparent Magnitude5.29
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)12h 28m 54.72
Declination (Dec.)+25° 54` 46.4
Galactic Latitude84.82 degrees
Galactic Longitude225.22 degrees
1997 Distance from Earth12.06 Parallax (milliarcseconds)
 270.45 Light Years
 82.92 Parsecs
2007 Distance from Earth13.72 Parallax (milliarcseconds)
 237.73 Light Years
 72.89 Parsecs
Galacto-Centric Distance24,152.40 Light Years / 7,405.00 Parsecs
Proper Motion Dec.-15.46 ± 0.17 milliarcseconds/year
Proper Motion RA.-21.94 ± 0.25 milliarcseconds/year
B-V Index-0.05
Radial Velocity-1.40 ± 0.50 km/s
Eccentricity0.08
Semi-Major Axis7869.00
Stellar Luminosity (Lsun)49.36
Associated / Clustered Stars17 Comae Berenices

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassRotating
Variable Star TypeAlpha2 Canum Venaticorum
Mean Variability Period in Days5.079
Variable Magnitude Range (Brighter - Dimmer)5.231 - 5.253

Estimated Facts


Calculated Effective Temperature11,775 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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