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

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 (τ ∼ 1–2 Myr) with measured luminosities, spectral types, and optical veiling. We combined the archival sample with the Two Micron All Sky Survey and Wide-field Infrared Survey Explorer 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.