Formation of the hydrogen n=30 alpha line

Background

The solar chromosphere is very dynamic permeated by episodic heating events and propagating acoustic waves that steepen into shocks. It is difficult to observationally determine how the thermodynamic variables, like density and temperature, vary because most diagnostic spectral features formed there are formed outside Local Thermodynamic Equilibrium (LTE) and are very non-linearly and non-locally dependent on the conditions. ALMA provides diagnostics that are more linearly and locally dependent on the physical conditions, thus offering a complementary diagnostic opportunity. One spectral line that falls within the ALMA bands is the transition between n=30 and n=31 in neutral hydrogen.

Goal

The goal of this project is to study the formation of the hydrogen n=30 alpha line.

Method

 

1. Set up the radiative transfer problem using the code RH.

 

 

A 40-level hydrogen model atom in MULTI format: atom.h40. On the institute machines it can also be found at /mn/stornext/u3/matsc/multi/input/atom.h40. The RH package contains routines to convert from MULTI format to RH format. Start with using the VAL3C model atmosphere.

 

2. Compare the RH results with the MULTI results.

 

 

Pay special attention to background opacities and the Starck broadening.

 

3. Study the sensitivity to the Starck broadening.

 

 

Use several different model atmospheres, also with shocks present. Run with different values of the Starck broadening.