STARS

<p class="default">Dec 9, 2009 7:27 PM &#160;<b>HR Diagrams: </b>&#160;the X axis is supposed to be (and is) <b>spectrum/color .</b>..

it uses the UBV or ultraviolet, blue, visible system &#160;(Note: &#160;V means VISIBLE not violet)

So &#160;Shorter wavelengths are on the Left (violet or blue) and &#160;Longer wavelengths are on the right

(redder colors). &#160;The Sun is Yellow and is in the middle of the main sequence.

and is Luminosity 1. &#160;Hot stars give off more blue light than red; cool stars give off more red light than blue. &#160;The main sequence is a reflection of MASS (I think).</p>