RASCAS Grid of Idealised Models

Numerical setup

The simulations have been performed with the RASCAS 3D Monte Carlo code (Michel-Dansac et al., 2020) on a regular 3D 256³ cartesian grid. The emission is assumed to be a point source located at the center of a spherical wind. The scattering medium, described as static or outflowing gas, extends from $R_{\rm in}$ to $R_{\rm out}$.

Wind parameters

• Integrated gas column density $N$ (atoms/cm²) from the $R_{\rm in}$ to $R_{\rm out}$.
• Density profile defined as: $\rho(r) = \rho_{\rm 0} {\large{\left(\frac{R_{\rm in}}{r}\right)}}^{\large{{\alpha}}_{\large{{\rm D}}}}$ where $\rho_{\rm 0}$ is the normalisation factor set by the chosen value of $N$ and ${\alpha}_{{\rm D}} = 0$ (uniform density) or $2$ (isothermal sphere).
• $V_{\rm max}$ is the maximum wind velocity (in km/s).
• Velocity profile defined as : $V(r) = V_{\rm max} {\large{\left(\frac{r}{R_{\rm out}}\right)}}^{\large{{\alpha}}_{\large{{\rm V}}}}$ for $\large{\alpha}_{\large{{\rm V}}}$ = 0 or 1, and $V(r)$ = $V_{\rm max} {\large{\left(\frac{R_{\rm out} - \: r}{R_{\rm out} - R_{\rm in}}\right)}}$ labelled as $\large{\alpha}_{\large{{\rm V}}}$ = -1 models.
• Doppler parameter $b_{\rm }$ (km/s) accounting for unresolved thermal/turbulent gas motions.
• Integrated dust opacity $\large{\tau_{\rm d}}$ from $R_{\rm in}$ to $R_{\rm out}$. Dust is assumed to be homogeneously mixed with the gas so the dust density profile follows that of $\rho(r)$.

Reading the data

import numpy as np
file = 'XXX.dat'
lbda,flux=np.loadtxt(file,skiprows=6,unpack=1) # lambda in A ; flux normalised to the continuum