We present 2-D radiation transfer models of Class I Protostars and show theeffect of including more realistic geometries on the resulting spectral energydistributions and images. We begin with a rotationally flattened infallingenvelope as our comparison model, and add a flared disk and bipolar cavity. Thedisk affects the spectral energy distribution most strongly at edge-oninclinations, causing a broad dip at about 10 um (independent of the silicatefeature) due to high extinction and low scattering albedo in this wavelengthregion. The bipolar cavities allow more direct stellar+disk radiation to emergeinto polar directions, and more scattering radiation to emerge into alldirections. The wavelength-integrated flux, often interpreted as luminosity,varies with viewing angle, with pole-on viewing angles seeing 2-4 times as muchflux as edge-on, depending on geometry. Thus, observational estimates ofluminosity should take into account the inclination of a source. The envelopeswith cavities are significantly bluer in near-IR and mid-IR color-color plotsthan those without cavities. Using 1-D models to interpret Class I sources withbipolar cavities would lead to an underestimate of envelope mass and anoverestimate of the implied evolutionary state. We compute images at near-,mid-, and far-IR wavelengths. We find that the mid-IR colors and images aresensitive to scattering albedo, and that the flared disk shadows the midplaneon large size scales at all wavelengths plotted. Finally, our models producepolarization spectra which can be used to diagnose dust properties, such asalbedo variations due to grain growth. Our results of polarization across the3.1 um ice feature agree well with observations for ice mantles covering 5% ofthe radius of the grains.
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