Formation of molecular lines in the solar atmosphere

Background

Molecular lines in the solar spectrum can be used to diagnose the coolest plasma. Observations indicated the presence of plasma cooler than exists in typical semi-empirical atmospheric models (like the FALC model), see e.g. discussion in Wedemeyer-B?hm et al (2005). On the other hand, 3D simulations often give very low temperature in the outer parts, so low that we do not know what mechanism stops the cooling (Leenaarts et al (2011). It is unclear how sensititve CO lines are to localized cool pockets in the solar lower chromosphere.

Goal

The goal of the project is to study the formation of the CO lines in a 3D simulation of the solar chromosphere to determine the diagnostic power of these lines for the coolest pockets of the atmosphere.

Method

The RH 1.5D code is used to solve the equations of statistical equilibrium for a given model atom and model atmosphere.

Procedure

  1. Set up an appropriate atomic model for CO.
  2. Use snapshot 385 from the simulation en024048_hion as model atmosphere (/mn/stornext/u3/matsc/rh/Atmos/en024048_hion_385.ncdf)
  3. Use RH to calculate the CO spectrum
  4. Look at the lines at different positions to determine the sensitivity to low temperatures