Measuring Optical Extinction Towards Young Stellar Objects Using Diffuse Interstellar Bands

TL;DR

This study introduces a novel method using diffuse interstellar bands to estimate line-of-sight extinction towards young stellar objects, addressing inconsistencies in previous measurements and providing a more reliable approach.

Contribution

The paper develops a new calibration linking DIB equivalent widths to extinction specifically for young stellar objects, improving accuracy over prior methods.

Findings

DIBs correlate with extinction in young stars.

New calibration accounts for measurement scatter.

Comparison shows improved extinction estimates.

Abstract

Line-of-sight extinction estimates to well-studied young T Tauri and Herbig Ae/Be stars are based on many different measurements and analysis methods. This has resulted in wide scatter among the published $A_V$ values for the same star. In this work, we discuss the challenges in measuring extinction to actively accreting and especially outbursting young stellar objects (YSOs). We then explore a method not previously applied to young stars utilizing diffuse interstellar bands (DIBs). In early-type stars, narrow correlations exist between DIB equivalent widths and the column density of interstellar material, and therefore the line-of-sight extinction. Here, we measure equivalent widths of the 5780 \AA\ and 6614 \AA\ DIB features in a sample of actively accreting YSOs, and apply a DIB-reddening calibration to estimate reddening and subsequently extinction. Our calibration is newly derived from a composite of available literature data and fully accounts for the scatter in these measurements. We also compare the DIBs-inferred optical line-of-sight extinction values with previous extinction estimates for our sample stars.