Castor B (Alpha Geminorum B) is a blue star that can be located in the constellation of Gemini. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
Alpha Geminorum B is the Bayer Classification for the star.
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 Castor B, the location is 07h 34m 36.10 and +31 d 53` 18.57 .
Castor B has a spectral type of Am. This means the star is a blue star.
Castor B has an apparent magnitude of 2.97 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. 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.
|Traditional/Proper Name||Castor B|
|Bayer Designation||Alpha Geminorum B|
|Visual / Apparent Magnitude||2.97|
|Naked Eye Visible||Yes - Magnitudes|
|Right Ascension (R.A.)||07h 34m 36.10|
|Declination (Dec.)||+31 d 53` 18.57|
|Associated / Clustered Stars||Castor|
The map was generated using Night Vision, an awesome free application by Brian Simpson.