Formation of the H-alpha line in spicules
Background
The Balmer-alpha line from atomic hydrogen is very much used as a diagnostic line of the solar chromosphere. Filtergrams taken with a narrow filter at line-center shows a very fibrilar structure. Dopplergrams formed by taking the difference of intensity between the red and blue wing show large velocities in thin structures.Goal
The goal of the project is to show how the H-alpha line is formed and how it can be used as diagnostics of the solar atmosphere. A specific goal is to investigate the conditions needed to get fibrilar structures similar to the ones observed.Method
MULTI is used to solve the equations of statistical equilibrium for a given model atom and model atmosphere.Procedure
As a first step you should study the formation in the semi-empirical atmosphere VAL3C. Use the following files from the distribution
atom.h6
dscale.h6_val3c
input.h6
Compile and run MULTI.
Study the frequency quadrature of all lines. Does the last frequency point extend to the continuum? If not, adjust the value of QMAX. NB! This should NOT be done for the Lyman lines - these have a truncated profile to mimic effects of partial distribution. Change the value of NQ so there are enough points across the line profile (around 100).
Get an atmosphere that extends into the corona. Use ~matsc/multi/input/atmos.282_000 and ~matsc/multi/input/dscale.282_000. You may need to increase the number of depth points.
Check the depth-discretization through the printout in the out file. Use the DSCAL2 procedure if needed.
Add a region of a given thickness similar to the thickness of spicules at a given height in the atmosphere. Make sure that dscale covers this region with enough points. Adjust the density in this layer - test various densities/temperature to see what is needed to get enough optical thickness over the slab. Use parameters that are reasonable given the observed characteristica of spicules.