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•Continuous spectrum B-B radiation ® T*
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•Spectral classification ® T*
•tightly bound atoms (e.g. H and He) can survive to 20,000K
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• weakly bound
atoms are ionized above ~ 8000K
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• molecules survive
only up to ~3000K
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• e.g.
if O, Ca, Mg lines observed, but no molecules
• T ~ 5000-8000K
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