Castor B (Alpha Geminorum B) is a blue Multiple Star System that can be located in the constellation of Gemini. 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.
Alpha Geminorum B is the Bayer Classification for the star.
More details on star alternative names can be found at Star Names .
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 Castor B, the location is 07h 34m 36.10 and +31 ° 53` 18.57 .
Castor B has a spectral type of Am. This means the star is a blue Multiple Star System.
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.
|Alternative Names||Alpha Geminorum B|
|Multiple Star System||Yes|
|Star Type||Multiple Star System|
|Visual / Apparent Magnitude||2.97|
|Naked Eye Visible||Yes - Magnitudes|
|Right Ascension (R.A.)||07h 34m 36.10|
|Declination (Dec.)||+31 ° 53` 18.57|
|Associated / Clustered Stars||Castor|
The map was generated using Night Vision, an awesome free application by Brian Simpson.