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1. Stephen Sekula (steve@chirp.cooleysekula.net)'s status on Sunday, 18-Sep-2016 19:43:22 UTC Stephen Sekula
   For the record, the Hertzsprung-Russel (HR) diagram is one of the coolest things ever. Get to know a star today. https://chirp.cooleysekula.net/attachment/15611
   • @mcscx@quitter.se likes this.
   • Former Bob Jonkman -- Please use the new server at https://gs.jonkman.ca (bobjonkmanformer@sn.jonkman.ca)'s status on Monday, 19-Sep-2016 00:01:31 UTC Former Bob Jonkman -- Please use the new server at https://gs.jonkman.ca

     in reply to
     Just the sort of poster I'd like to have framed in my office! https://chirp.cooleysekula.net/file/db3cd0aba109f1da7660256c60cfebacaf3198c488b299dbd7af79c946dc6680.png
     solariiknight(ஆனந்த்) likes this.
   • Former Bob Jonkman -- Please use the new server at https://gs.jonkman.ca (bobjonkmanformer@sn.jonkman.ca)'s status on Monday, 19-Sep-2016 00:04:15 UTC Former Bob Jonkman -- Please use the new server at https://gs.jonkman.ca

     in reply to
     @steve I'm curious how the age of the stars would appear on this diagram. Would there be regular iso lines for age, as there are iso lines for radius?
   • Stephen Sekula (steve@chirp.cooleysekula.net)'s status on Tuesday, 20-Sep-2016 21:22:15 UTC Stephen Sekula

     in reply to

     • Former Bob Jonkman -- Please use the new server at https://gs.jonkman.ca
     @bobjonkman Age is a separate axis. For instance, stars (once nuclear burning begins) spend 90% of their lives at a fixed location on "main sequence". Once they end hydrogen fusion, they leave the main sequence and begin a process of zig-zagging back and forth above and to the right of the main sequence, fusing heavier and heavier elements. What happens after that depends on the mass of the original Star. But the absolute amount of time spent on the main sequence depends on the mass. If a blue giant star is formed, it leaves the main sequence after about 10 million years. If a sun-like star is formed, it leaves the main sequence after 10 billion years. Red-orange stars take even longer. So 90% translates into a very different actual length of time, and that time is a function of the original mass of the star when it formed. You need one more axis for this.