barak.absorb.calc_tau_peak¶

barak.absorb.calc_tau_peak(logN, b, wa0, osc)[source]¶

Find the optical depth of a transition at line centre assuming we are on the linear part of the curve of growth.

Parameters :	logN : array_like log10 of column density in cm^-2 b : float b parameter in km/s. wa0 : float Rest wavelength of the transition in Angstroms. osc : float Transition oscillator strength.
Returns :	tau0 : ndarray or scalar if logN is scalar optical depth at the centre of the line

Notes

See Draine “Physics of the Interstellar and Intergalactic medium” for a description of how to calculate this quantity.