The Technique

  • In eclipse, the emission spectrum is integrated over the entire star.
  • Outside of eclipse, the emission flux is insignificant.
  • The absorption on the LoS selectively probes a beam about 8000 km in diameter.
  • The absorption line profiles yield
    • gas velocity
    • gas temperature
    • column density of each species
    • gas density
  • In principle, we can determine T(h) and P(h)

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