Optical and Near-Infrared Excesses are Correlated in T Tauri Stars

TL;DR

This study demonstrates a correlation between optical and near-infrared excesses in T Tauri stars, indicating linked disk and accretion processes, with implications for understanding protoplanetary disk evolution.

Contribution

It provides the first comprehensive analysis of the relationship between NIR and optical excesses in both single and binary T Tauri stars using archival data.

Findings

NIR and optical excesses are correlated across multiple bands.

Higher disk mass correlates with increased accretion rates.

Multiplicity does not significantly affect disk or accretion properties in the studied sample.

Abstract

Accretion is one of the defining characteristics of classical T Tauri stars, fueled by the presence of a circumstellar disk comprised of dust and gas. Accretion produces a UV and optical excess, while re-radiated emission at the inner edge of the dust component of the disk produces a near-infrared (NIR) excess. The interplay between stars and their disks helps regulate protoplanetary disk evolution and dispersal, which is key to a full understanding of planet formation. To investigate the relations between NIR excess and optical excess in both single and binary stars, we used an archival sample of spectroscopically characterized members of the Taurus star-forming region ($\tau \sim$ 1-2 Myr) with measured luminosities, spectral types, and optical veiling. We combined the archival sample with 2MASS and WISE NIR photometry and high-resolution imaging surveys. We found that NIR and optical excesses are correlated in multiple NIR photometric bands, suggesting that they are closely related, likely because more massive disks have higher inner dust disk walls and are also associated with higher accretion rates. We also found that multiplicity has no impact on accretion or inner disk properties in a sample with a wide range of separations, but the sample was too small to specifically investigate close binaries, where the effects of multiplicity on disk properties should be most significant.