load_chianti_lines_lite#
- sunkit_spex.io.load_chianti_lines_lite()[source]#
Read X-ray emission line info from an IDL sav file produced by CHIANTI.
This function does not read all data in the file, but only that required to calculate the observed X-ray spectrum.
- Returns:
line_intensities_at_source – Intensities of each of each line as a function of temperature and associated metadata and coordinates.
- Return type:
xarray.DataArray
Notes
CHIANTI File
By default, this function uses the file located at https://hesperia.gsfc.nasa.gov/ssw/packages/xray/dbase/chianti/chianti_lines_1_10_v71.sav. To use a different file (created by CHIANTI and saved as a sav file) call this function in the following way: >>> from sunpy.data import manager # doctest: +SKIP >>> with manager.override_file(“chianti_lines”, uri=filename): # doctest: +SKIP … line_info = load_chianti_lines_light() # doctest: +SKIP
where filename is the location of the file to be read.
Intensity Units
The line intensities read from the CHIANTI file are in units of ph / cm**2 / s / sr. Therefore they are specific intensities, i.e. per steradian, or solid angle. Here, let us call these intensities, intensity_per_solid_angle. The solid angle is given by flare_area / observer_distance**2. Total integrated intensity can be rewritten in terms of volume EM and solid angle:
intensity = intensity_per_solid_angle_per_volEM * volEM * solid_angle intensity = intensity_per_solid_angle / (colEM * flare_area) * (flare_area / observer_dist**2) * volEM intensity = intensity_per_solid_angle / colEM / observer_dist**2 * volEM
i.e. flare area cancels. Therefore:
intensity = intensity_per_solid_angle / colEM / observer_dist**2 * volEM,
or, dividing both sides by volEM,
intensity_per_EM = intensity_per_solid_angle / colEM / observer_dist**2
In this function, we normalize the intensity by colEM and scale it to the source, i.e. intensity_out = intensity_per_solid_angle / colEM * 4 * pi Therefore the intensity values output by this function must be multiplied by EM and divided by 4 pi observer_dist**2 to get physical values at the observer.