Lunch talk on Apr. 20, 2020

The Optical to Mid-Infrared Extinction Law--An Adjustment to the Classic Rv=3.1 Extinction Law  

Speaker: Shu Wang (NAOC)

Venue: Video conference

Time: 12:30 PM, Monday, April 20, 2020

Abstract: 

A precise interstellar dust extinction law is critically important to interpret observations. There are two indicators of extinction: the color excess ratio (CER) and the relative extinction. Compared to the CER, the wavelength-dependent relative extinction is more challenging to be determined. In this talk, I will present the results of our high-precision CERs (reddening law) and extinction ratios (extinction law) from optical to mid-infrared (IR) bands. For the first time, we calibrate the curvature of CERs, hence, the precision of CERs is significantly improved. Given no bias toward any specific environment, our observed extinction law supports an adjustment in parameters of CCM Rv=3.1 curve together with the near-IR power law index alpha=2.07+-0.03. Based on the APOGEE sample, the extinction law is universal within 4 kpc and Av < 6 mag. As the observed reddening/extinction tracks are curved, the curvature correction needs to be considered when applying extinction correction.

Report PPT:  SWIFAR_Shu Wang.pdf