| MadSci Network: Astronomy |
A star's colour reveals its surface temperature. Rukbat's (B-V) index is -0.10. This colour index indicates how much brighter or dimmer a star is in one wavelength band (blue, B) over the cental region of the coloured spectrum (visual, V). Since the value is negative, it means that Rukbat is brighter in the blue.
Once you have that value, you can check it against a graph of temperature versus (B-V) and you get about 15000 K for Rukbat, which is more or less 15000 C. (To get Celsius degrees from Kelvin, you have to subtract 273.) Such a surface temperature is considered very high.
To learn more about astronomy, read Kaufmann's book "Universe", or get the cd-rom "Redshift". These sources may challenge your mind a little more than astrology.
[Also see Chris Dolan's entry of Rukbat.]
Try the links in the MadSci Library for more information on Astronomy.