Ionized Hydrogen models¶
Hydrogen Models¶
Hydrogen in HII regions is typically assumed to follow Case B recombination theory.
The values for the Case B recombination coefficients are given by Hummer & Storey (1987). They are also computed in Hummer (1994) and tabulated at a wiki. I had to OCR and pull out by hand some of the coefficients.
Module API¶
-
pyspeckit.spectrum.models.hydrogen.
add_to_registry
(sp)[source] [github] [bitbucket]¶ Add the Hydrogen model to the Spectrum’s fitter registry
-
pyspeckit.spectrum.models.hydrogen.
find_lines
(xarr)[source] [github] [bitbucket]¶ Given a
pyspeckit.units.SpectrosopicAxis
instance, finds all the lines that are in bounds. Returns a list of line names.
-
pyspeckit.spectrum.models.hydrogen.
hydrogen_fitter
(sp, temperature=10000, tiedwidth=False)[source] [github] [bitbucket]¶ Generate a set of parameters identifying the hydrogen lines in your spectrum. These come in groups of 3 assuming you’re fitting a gaussian to each. You can tie the widths or choose not to.
- temperature [ 5000, 10000, 20000 ]
- The case B coefficients are computed for 3 temperatures
- tiedwidth [ bool ]
- Should the widths be tied?
Returns a list of
tied
andguesses
in the xarr’s units
-
pyspeckit.spectrum.models.hydrogen.
hydrogen_model
(xarr, amplitude=1.0, width=0.0, velocity=0.0, a_k=0.0, temperature=10000)[source] [github] [bitbucket]¶ Generate a set of parameters identifying the hydrogen lines in your spectrum. These come in groups of 3 assuming you’re fitting a gaussian to each. You can tie the widths or choose not to.
Parameters: - sp : pyspeckit.Spectrum
The spectrum to fit
- temperature : [ 5000, 10000, 20000 ]
The case B coefficients are computed for 3 temperatures
- a_k : float
The K-band extinction normalized to 2.2 microns. Simple exponential.
- width : float
Line width in km/s
- velocity : float
Line center in km/s
- amplitude : float
arbitrary amplitude of the first line (all other lines will be scaled to this value)
Returns: - np.ndarray with same shape as sp.xarr
-
pyspeckit.spectrum.models.hydrogen.
rrl
(n, dn=1, amu=1.007825, Z=1)[source] [github] [bitbucket]¶ compute Radio Recomb Line freqs in GHz from Brown, Lockman & Knapp ARAA 1978 16 445
- UPDATED:
- Gordon & Sorochenko 2009, eqn A6
Parameters: - n : int
The number of the lower level of the recombination line (H1a is Lyman alpha, for example)
- dn : int
The delta-N of the transition. alpha=1, beta=2, etc.
- amu : float
The mass of the central atom
- Z : int
The ionization parameter for the atom. Z=1 is neutral, Z=2 is singly ionized, etc. For hydrogen, only z=1 makes sense, since ionized hydrogen has no electrons and therefore cannot have recombination lines.
Returns: - frequency in GHz