HIP22234 is the reference name for the star in the Hipparcos Star Catalogue.
BC Eridani has alternative name(s) :- BC Eri, BC Eri.
More details on objects' alternative names can be found at Star Names .
The location of the variable 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 BC Eridani, the location is 04h 46m 59.00 and -14° 37` 23.3 .
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 -6.44 ± 1.01 milliarcseconds/year towards the north and 16.68 ± 1.91 milliarcseconds/year east if we saw them in the horizon.
The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 65.00 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.
BC Eridani has a spectral type of A6. This means the star is a blue variable star. The star has a B-V Colour Index of 0.49 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,140 Kelvin.
Radius has been calculated as being 2.33 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,618,169.79.km. If you need the diameter of the star, you just need to multiple the radius by 2. 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 -1.12 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.
BC Eridani has an apparent magnitude of 10.91 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 2.75 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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.33 which gave the calculated distance to BC Eridani as 1399.84 light years away from Earth or 429.18 parsecs. It would take a spaceship travelling at the speed of light, 1399.84 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is a eclipsing W Ursae Majoris/Cont 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. BC Eridani brightness ranges from a magnitude of 11.500 to a magnitude of 10.895 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 days (variability).
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.
|Primary / Proper / Traditional Name||BC Eridani|
|Alternative Names||BC Eri, HIP 22234, BC Eri|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Variable Star|
|Visual / Apparent Magnitude||10.91|
|Naked Eye Visible||Requires a 4.5 - 6 Inch Telescope - Magnitudes|
|Right Ascension (R.A.)||04h 46m 59.00|
|Declination (Dec.)||-14° 37` 23.3|
|Galactic Latitude||-34.06 degrees|
|Galactic Longitude||212.70 degrees|
|Distance from Earth||2.33 Parallax (milliarcseconds)|
|1399.84 Light Years|
|88,524,112.70 Astronomical Units|
|Proper Motion Dec.||-6.44 ± 1.01 milliarcseconds/year|
|Proper Motion RA.||16.68 ± 1.91 milliarcseconds/year|
|Radial Velocity||65.00 ± 7.40 km/s|
|Iron Abundance||-1.12 ± 9.99 Fe/H|
|Variable Star Class||Eclipsing|
|Variable Star Type||W Ursae Majoris/Cont|
|Mean Variability Period in Days||0.527|
|Variable Magnitude Range (Brighter - Dimmer)||10.895 - 11.500|
|Radius (x the Sun)||2.33|
|Effective Temperature||6,140 Kelvin|
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