A python code to generate the extinction law between 0.8 -- 2.2 microns as described in Hosek+18. The law is derived using the Westerlund 1 (Wd1) main sequence (A_Ks ~ 0.6 mag) and Arches cluster field Red Clump at the Galactic Center (A_Ks ~ 2.7 mag). To derive the law a Wd1 cluster age of 5 Myr is assumed, though changing the cluster age between 4 Myr -- 7 Myr has no effect on the law.
This extinction law can be applied to highly reddened stellar populations that have similar foreground material as Wd1 and the Arches RC, namely dust from the spiral arms of the Milky Way in the Galactic Plane.
- python (either 2.7 or higher)
- numpy
- scipy
- pylab
extinction(AKs, wavelength): returns the total extinction A_lambda and corresponding error (1-sigma) at the specified wavelength(s) and overall A_Ks. The wavelengths must be in microns and A_Ks in magnitudes. Input wavelength(s) can either be a float or array of floats. The reported 1-sigma errors are statistical only. See Table 4 of Hosek+18 for estimates of the systematic error.
plot_extinction_law(): Plot the extinction law (with errors) between 0.8 -- 2.2 microns. Saves output plot as extlaw_H18.png in working directory.
To get the total extinction at 1.25 microns and A_Ks = 0.5 mags (in an ipython session):
import extlaw_H18 # Import code
result, err = extlaw_H18.extinction(0.5, 1.25)
print(result) # extinction at 1.25 microns
print(err) # 1-sigma err (statistical)