Fix the definition of hydrogenic and helium-like ions

[jwreep]

Fixes #251

Please review.

I don't think that this line

fiasco/fiasco/ions.py

Line 975 in 282b819

B = 1 if self.hydrogenic else 2

needs to be changed since the function it's embedded in is only called for heavier elements.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (282b819) 90.56% compared to head (180fdc6) 90.56%.

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #252   +/-   ##
=======================================
  Coverage   90.56%   90.56%           
=======================================
  Files          36       36           
  Lines        2670     2670           
=======================================
  Hits         2418     2418           
  Misses        252      252           

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[wtbarnes]

Suggested change

	if (self.hydrogenic and self.atomic_number >= 6) or
	(self.helium_like and self.atomic_number >= 10):
	if ((self.hydrogenic and self.atomic_number >= 6) or
	(self.helium_like and self.atomic_number >= 10)):

[jwreep]

Yeah, just noticed the tests failed. Fixing it now...

[jwreep]

Too much C++ in my brain.

[jwreep]

I'm not sure I understand that last check that's failing. Any idea what the issue is?

[wtbarnes]

The pre-commit job runs several style checks on the changes to ensure consistent code style across the package. I can fix that easily. You can also install the pre-commit hooks locally using these instructions: https://docs.sunpy.org/en/latest/dev_guide/contents/code_standards.html#formatting and it will fix the files for you.

[jwreep]

Thank you! I didn't know about that. I'll make sure to use it going forward.

[wtbarnes]

@pryoung also pointed out to me that the Fontes and Dere papers note that the fits to the Fontes cross-sections should be accurate for $Z\ge4$, but then there's an additional note that Li III and B V are better fit with the BT scaled cross-section data and that the Be IV cross-sections are fit using the B V cross-sections appropriately scaled by the ionization potential. Thus, the $Z\ge6$ requirement is presumably to ensure those three ions are not fit using Fontes and instead use the .diparams values.

Interestingly, .diparams values are available for C VI, despite the fact that that cross-section is fit using Fontes. A plot of these two cross-sections is shown below,