THE INFRARED REFLECTION NEBULA AROUND THE EMBEDDED SOURCES IN S-140

We have observed the protostellar system in S 140 at 2.2, 3.1 and 3.45 mu m using a 128x128 InSb array camera with the Lick Observatory 3m t elescope. We have developed a simple model of this region which has be en used to derive the physical conditions of the dust and gas. IRS 1 i s surrounded by a dense dusty disk viewed almost edge-on. Photons leak ing out through the poles of the disk illuminate the inner edge of a s urrounding shell of molecular gas as seen at locations NW and VLA4. Th e optical depth at K through the poles of the disk is about 0.22, whil e A(V)=30 towards IRS1. Analysis of the observed colors and intensitie s of the NIR light, using Mie scattering theory, reveals that the dust grains in the molecular cloud are somewhat larger than in the general diffuse interstellar medium. Moreover, the incident light has a ''coo l'' color temperature, similar or equal to 850-900K, and likely origin ates from a dust photosphere close to the protostar. There is little H 2O ice associated with the dusty disk around IRS1. Most of the 3.1 mu m ice extinction arises instead from cool intervening molecular cloud material. We have also compared our infrared dust observations with mi llimeter and radio observations of molecular gas associated with this region. The large scale structure observable in the molecular gas is i ndicative of the interaction between the protostellar wind and the sur rounding molecular cloud rather than the geometry of the protostellar disk, We conclude that S 140 is a young blister formed by this outflow on the side of a molecular cloud and viewed edge-on.