High Spatial Resolution Near-Infrared Images of Taurus Protostars

We analyze near-infrared K- and L-band images of six embedded Class I objects in the Taurus-Auriga molecular cloud. Three of these sources were observed in both bands and three were observed only at L. The L- and K-band images were obtained with the Cryogenic Optical Bench at the KPNO 4 m telescope in the diffraction-limited mode. With the high spatial resolution L-band data, we identify IRAS 04239+2436 as a close pair with a projected separation of 0.29''. We use a radiative transfer code to model the images and derive physical and geometrical parameters for each source. Because the projected positions of the six analyzed sources on the cloud coincide with the densest zones in the complex (A_V ∼ 10-30 mag), we use two models for the optical properties of dust grains in the envelopes: a diffuse ISM model and a grain model with ratio of total to selective extinction R_V = 4.3 corresponding to the measured R values in the densest regions of the Taurus molecular cloud. Although the two grain models have different opacities, we can match the observed images with either model by selecting the appropriate envelope infall rate. Thus we cannot distinguish between the two grain models over this narrow wavelength range (K and L bands).