MolecularHydrogen

class msaexp.utils.MolecularHydrogen(**kwargs)

Bases: object

Tools for working with molecular hydrogen lines using the helpful relations from Aditya Togi and J. D. T. Smith 2016 ApJ, 830, 18

Optically thin flux:

\[F_j = h \nu A N_{j+2} \Omega / 4\pi\]

Line flux F as a function of temperature, T (excitation diagram):

\[ \begin{align}\begin{aligned}N_{j+2} = \frac{g_{j+2}}{Z(T)} e^{-E_\mathrm{upper} / kT}\\Z(T) = \sum g_j e^{-E_j / kT}\\F_j \propto \frac{N_{j+2} A}{\lambda}\end{aligned}\end{align} \]

Line data from the Gemini compilation at https://www.gemini.edu/observing/resources/near-ir-resources/spectroscopy/important-h2-lines

Attributes Summary

N	Length of data table
h_nu_A	precompute \(h \cdot \nu \cdot A\) (erg / second)
ix	Index of the reference transition (usually "1-0 S(1)") in the data table
nu	Transition frequency
reference
separate_ZT

Methods Summary

Nj([T])	Compute number density: \(N_j = \frac{g_j}{Z(T)}~e^{-E_j / kT}\)
ZT([T])	Compute \(Z(T) = \sum g_j e^{-E_j / kT}\)
h2_mass([line_flux, transition, z])	Still figuring out unit conversions....
initialize_flux_table()	Initialize flux table
line_flux([T])	Line flux \(F_j = h \nu A N_{j+2} \Omega / 4\pi\)
line_names([prefix])	LaTeX line names
load_data()	Read the data table and set the units on some columns
spec_model(spec[, z, update_flux, ...])	Make an MSAEXP model
temperature_powerlaw([n, Tl, Tu, nsteps])	Generate a powerlaw temperature distribution \(dN = T^{-n} dT\)
to_linelist()	Reformat into a LineList object
update_flux_table([T, min_line_fraction, ...])	Get a list of lines and ratios

Attributes Documentation

N

Length of data table

h_nu_A

precompute \(h \cdot \nu \cdot A\) (erg / second)

ix

Index of the reference transition (usually “1-0 S(1)”) in the data table

nu

Transition frequency

reference = ('1-0', 'S(1)')

separate_ZT = False

Methods Documentation

Nj(T=1000.0)

Compute number density: \(N_j = \frac{g_j}{Z(T)}~e^{-E_j / kT}\)

ZT(T=1000.0)

Compute \(Z(T) = \sum g_j e^{-E_j / kT}\)

h2_mass(line_flux=<Quantity 1.e-20 erg / (s cm2)>, transition=('1-0', 'S(1)'), z=1.01, **kwargs)

Still figuring out unit conversions….

initialize_flux_table()

Initialize flux table

line_flux(T=1000.0, **kwargs)

Line flux \(F_j = h \nu A N_{j+2} \Omega / 4\pi\)

line_names(prefix='H$_2$')

LaTeX line names

load_data()

Read the data table and set the units on some columns

spec_model(spec, z=0.0, update_flux=True, wave_range=None, fnu=True, single=True, **kwargs)

Make an MSAEXP model

static temperature_powerlaw(n=4.5, Tl=50, Tu=2000, nsteps=16)

Generate a powerlaw temperature distribution \(dN = T^{-n} dT\)

to_linelist()

Reformat into a LineList object

update_flux_table(T=1000.0, min_line_fraction=0.05, wave_range=(1.6, 2.6), **kwargs)

Get a list of lines and ratios