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Sense larger T range using many atoms
•Different
atoms hold on to electrons with different force
–Use tightly held electrons to sense high
temperatures (He, ionized He)
•Below 10,000K most He electrons in ground
state – just like H, no visible absorption lines
•Above 15,000K most H has lost one
electron, but still has a second one to cause absorptions
From our text: Horizons, by Seeds
