Nearly simultaneous optical and infrared photometry of T Tauri stars

Abstract

Nearly simultaneous UBVri and JHKL photometry is presented for 17 T Tauri and related young stars in the Taurus and NGC 2264 regions. The seven stars in our sample with extremely weak line emission have B - V colors which average about 0.1 bluer than expected from their V - i colors, assuming luminosity class V intrinsic colors and normal reddening. The intrinsic locus of our program stars in the (J - H,H - K) infrared two-color diagram is quite well defined and supports the dust-shell model for the infrared excess. Maximum dust temperatures in the approximate range 1000-1500 K are inferred from the intrinsic locus of our stars in the (H - K,K - L) diagram. Infrared excesses similar to those found in typical T Tauri stars are clearly present in several late-type young stars which have extremely weak emission-line spectra. Some BVri photometry for known T Tauri stars in the southern part of the Taurus complex is also presented.