juliaroquette / av_functions

Package with tools related to the use of Interestellar Extinction Laws for the Milky Way

@juliaroquette - 20 December 2023 This repository concentrates on functions related to the extinction law.

The extinction Law itself

In ExtinctionLaw.ipynb I am testing a few different extinction laws and choosing a combination of literature extinction laws as default. These are basically development notes behind the class ExtinctionLaw, which can be used to interpolate values of $\frac{A_\lambda}{A_V}$ for any $\lambda$ from 0.0001 -- 10000$\mu$m.

This is done employing the dust_extinction package from AstroPy. My current default extinction curve has the following assumptions:

1. $R_V=3.1$ - although in the future I may want to escalate this for other values of $R_V$.
2. For the range 0.2-12$\mu$m, I am adopting the Gordon et al. 2023 extinction law.
3. Outside this range, I am adopting an extinction law from dust-models by Draine (2003, ARA&A, 41, 241; 2003, ApJ, 598, 1017), who used the distribution of grains sizes from Weingartner & Draine (2001, ApJ, 548, 296).
4. The truncation limits in 2. are chosen by eye based on the comparison between the extinction curves in 2. and 3..
5. The upper and lower limit is defined by the availability of 3.
6. This extinction law is valid for the Milky Way.

TO DO:

• Include a function to provide A_lambda for given lambda.
• In the future this package will also allow deriving $A_\lambda$ for a given photometric system given a transmission curve.

Extinction derivations using the T-Tauri Locus

The jupyter-notebook get_Av_from_JHK_TTauriLocus.ipynb contains notes of the development of a code to estimate $A_V$ values for Young Stellar Objects (YSO) based on the JHKs-colour space using the Classical TTauri Locus as a reference.