IRAC Observations of Taurus Pre–Main‐Sequence Stars

We present infrared photometry obtained with the IRAC camera on the SpitzerSpace Telescope of a sample of 82 pre-main sequence stars and brown dwarfs inthe Taurus star-forming region. We find a clear separation in some IRACcolor-color diagrams between objects with and without disks. A few``transition'' objects are noted, which correspond to systems in which theinner disk has been evacuated of small dust. Separating pure disk systems fromobjects with remnant protostellar envelopes is more difficult at IRACwavelengths, especially for objects with infall at low rates and large angularmomenta. Our results generally confirm the IRAC color classification schemeused in previous papers by Allen et al. and Megeath et al. to distinguishbetween protostars, T Tauri stars with disks, and young stars without (inner)disks. The observed IRAC colors are in good agreement with recent improved diskmodels, and in general accord with models for protostellar envelopes derivedfrom analyzing a larger wavelength region. We also comment on a few Taurusobjects of special interest. Our results should be useful for interpreting IRACresults in other, less well-studied star-forming regions.Comment: 29 pages 10 figures, to appear in Ap