Hertzsprung-Russell diagram. A plot of luminosity (absolute magnitude) against the colour of the stars ranging from the high-temperature blue-white stars on the left side of the diagram to the low temperature red stars on the right side. "This diagram below is a plot of 22000 stars from the Hipparcos Catalogue together with 1000 low-luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. The ordinary hydrogen-burning dwarf stars like the Sun are found in a band running from top-left to bottom-right called the Main Sequence. Giant stars form their own clump on the upper-right side of the diagram. Above them lie the much rarer bright giants and supergiants. At the lower-left is the band of white dwarfs - these are the dead cores of old stars which have no internal energy source and over billions of years slowly cool down towards the bottom-right of the diagram." Converted to png and compressed with pngcrush.
<ul><li><a href="//commons.wikimedia.org/wiki/File:HRDiagram.png" title="File:HRDiagram.png">HRDiagram.png</a>: <a rel="nofollow" class="external text" href="http://www.atlasoftheuniverse.com/me.html">Richard Powell</a></li>
<li>derivative work: <a href="//commons.wikimedia.org/wiki/User:Leovilok" title="User:Leovilok">Leovilok</a> (<a href="//commons.wikimedia.org/wiki/User_talk:Leovilok" title="User talk:Leovilok"><span class="signature-talk">talk</span></a>)</li></ul>
CC BY-SA 2.5
<ul><li><a href="//commons.wikimedia.org/wiki/File:HRDiagram.png" title="File:HRDiagram.png">HRDiagram.png</a></li></ul>