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BH Draconis

BH Draconis Facts

BH Draconis's Alternative Names

HIP93595 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD178001.

BH Draconis has alternative name(s) :- BH Dra, BH Dra.

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+57 1942.

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

Location of BH Draconis

The location of the main sequence 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 object is compared to the celestial equator and is expressed in degrees. For BH Draconis, the location is 19h 03m 39.54 and +57° 27` 25.8 .

Radial Velocity and Proper Motion of BH Draconis

Proper Motion

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 1.38 ± 1.61 milliarcseconds/year towards the north and 5.03 ± 1.65 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -36.40 km/s with an error of about 7.40 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties (Colour, Temperature) of BH Draconis

BH Draconis Colour and Temperature

BH Draconis has a spectral type of A2Vp+.... This means the star is a blue main sequence star. The star has a B-V Colour Index of 0.04 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,025 Kelvin.

BH Draconis Radius

Radius has been calculated as being 1.41 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 978,300.12.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 1.67. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

BH Draconis Apparent and Absolute Magnitudes

BH Draconis has an apparent magnitude of 8.42 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 2.17 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.79. 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 BH Draconis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.63 which gave the calculated distance to BH Draconis as 579.33 light years away from Earth or 177.62 parsecs. It would take a spaceship travelling at the speed of light, 579.33 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 4.73 which put BH Draconis at a distance of 689.56 light years or 211.42 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.

Using the 2007 distance, the star is roughly 43,608,201.47 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

Variable Type of BH Draconis

The star is a eclipsing Beta Persei (Algol)/ 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. BH Draconis brightness ranges from a magnitude of 8.900 to a magnitude of 8.430 over its variable period. The smaller the magnitude, the brighter the star.

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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Additional BH Draconis Facts and Figures

Visual Facts


Primary / Proper / Traditional NameBH Draconis
Alternative NamesBH Dra, HD 178001, HIP 93595, BD+57 1942, BH Dra
Spectral TypeA2Vp+...
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
ColourBlue
GalaxyMilky Way
ConstellationDraco
Absolute Magnitude 2.17 / 1.79
Visual / Apparent Magnitude8.42
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)19h 03m 39.54
Declination (Dec.)+57° 27` 25.8
Galactic Latitude21.03 degrees
Galactic Longitude87.80 degrees
1997 Distance from Earth5.63 Parallax (milliarcseconds)
 579.33 Light Years
 177.62 Parsecs
2007 Distance from Earth4.73 Parallax (milliarcseconds)
 689.56 Light Years
 211.42 Parsecs
 43,608,201.47 Astronomical Units
Proper Motion Dec.1.38 ± 1.61 milliarcseconds/year
Proper Motion RA.5.03 ± 1.65 milliarcseconds/year
B-V Index0.04
Radial Velocity-36.40 ± 7.40 km/s

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassEclipsing
Variable Star TypeBeta Persei (Algol)/
Variable Magnitude Range (Brighter - Dimmer)8.430 - 8.900

Estimated Calculated Facts


Radius (x the Sun)1.67
Effective Temperature9,025 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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