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BW Draconis

BW Draconis Facts

BW Draconis's Alternative Names

HIP74368 is the reference name for the star in the Hipparcos Star Catalogue.

BW Draconis has alternative name(s) :- BW Dra.

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

Location of BW Draconis

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 object is compared to the celestial equator and is expressed in degrees. For BW Draconis, the location is 15h 11m 50.30 and +61° 51` 40.4 .

Radial Velocity and Proper Motion of BW 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 88.71 ± 4.73 milliarcseconds/year towards the north and -165.87 ± 4.75 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 -60.80 km/s with an error of about 1.15 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 BW Draconis

BW Draconis Colour and Temperature

BW Draconis has a spectral type of B0. This means the star is a blue star. The star has a B-V Colour Index of 0.69 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,671 Kelvin.

BW Draconis Radius

Radius has been calculated as being 1.08 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 751,660.63.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 1.25. 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 -0.54 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

BW Draconis Apparent and Absolute Magnitudes

BW Draconis has an apparent magnitude of 8.83 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 4.76 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.44. 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 BW Draconis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 15.32 which gave the calculated distance to BW Draconis as 212.90 light years away from Earth or 65.27 parsecs. It would take a spaceship travelling at the speed of light, 212.90 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 13.24 which put BW Draconis at a distance of 246.35 light years or 75.53 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 15,579,072.26 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.

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 BW Draconis Facts and Figures

Visual Facts


Primary / Proper / Traditional NameBW Draconis
Alternative NamesBW Dra, HIP 74368
Spectral TypeB0
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeStar
ColourBlue
GalaxyMilky Way
ConstellationDraco
Absolute Magnitude 4.76 / 4.44
Visual / Apparent Magnitude8.83
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)15h 11m 50.30
Declination (Dec.)+61° 51` 40.4
Galactic Latitude48.20 degrees
Galactic Longitude98.92 degrees
1997 Distance from Earth15.32 Parallax (milliarcseconds)
 212.90 Light Years
 65.27 Parsecs
2007 Distance from Earth13.24 Parallax (milliarcseconds)
 246.35 Light Years
 75.53 Parsecs
 15,579,072.26 Astronomical Units
Proper Motion Dec.88.71 ± 4.73 milliarcseconds/year
Proper Motion RA.-165.87 ± 4.75 milliarcseconds/year
B-V Index0.69
Radial Velocity-60.80 ± 1.15 km/s
Iron Abundance-0.54 ± 9.99 Fe/H

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)1.25
Effective Temperature5,671 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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