feature longward of Balmer, Paschen, etc jumps due to finite levels in H atom
User inquired into origin of absorption feature visible longward of Balmer jump. Attached smoke.jpg shows emitted continuum for smoke test with feature marked. Produced with
test
save emitted continuum units Angstroms
Figure high_resolution.jpg shows origin of figure. This has continuum resolution increased by factor of ten and is hydrogen-only for simplicity. The emission with the default number of H I levels is black. The gap between the highest emission and the Balmer Jump is due to our finite number of levels. The strong emission in the highest level is due to our topoff of the model. This was done with
test
init "honly.ini"
set continuum resolution 0.1
save diffuse continuum units Angstroms "hemis.con"
The red line shows the effects of increasing the number of collapsed levels so that we go above n = 100. The gap is largely filled in, but the high-n lines do not smoothly join onto the peak of the BJ. Probably many more levels would increase the merged line emission to bring it up to continuously join onto the BJ. This plots was done with
test
init "honly.ini"
set continuum resolution 0.1
atom h-like collapsed levels 100
save diffuse continuum units Angstroms "large.con"
In nature there is no feature at the join between the highest line emission and the continuum emission in the BJ - the absorption oscillator strength (used to get emission) is continuous between high-n Balmer lines and the BJ. With enough levels we should be able to reproduce this.
We do have extra lyman lines in the iso sequences to get smoother behavior in the absorption spectra. These are not done for higher n and are not done for emission since the lines would need to be transferred and have good population data. LTE would be a good assumption for highly excited n levels.
Calculations done with trunk at r7798.