HIGH-RESOLUTION FAR-INFRARED OBSERVATIONS AND RADIATIVE-TRANSFER MODELS OF W3 IRS 4 AND IRS 5

摘要

Far-infrared continuum maps made with the Kuiper Airborne Observatory of W3 at 47 and 95 μm show peaks identified with the mid-infrared sources IRS 4 and IRS 5 and extended emission identified with the radio source W3(A). We have first taken the steepest radial scan profiles from the peaks at IRS 4 and IRS 5 to represent the objects as spherical clouds. Maximum entropy method deconvolutions indicate that these radial scan profiles contain both compact cores and diffuse pedestals of emission. Spherically symmetric radiative-transfer dust-cloud models were created in an attempt to match these observed profiles. Models heated by central protostars or stars that match the 95 μm data do not match extended emission in the 47 μm scan profile for any assumed density distribution for either source. After the pedestals of diffuse emission were removed from the original scans to form new " core " scans, models were found that approximately match the profiles at both wavelengths. Depending on the exact dust properties assumed for the cloud, the models have either uniform or power-law radial-density gradients with an exponent of - 1. The cloud outer radii are 0.3-0.5 pc. Models for IRS 5 have central stellar luminosities of 2.5-3.5 x 10~5 solar luminosity, depending on the dust, and models for IRS 4 have 9.3 x 10~4 solar luminosity for both dust types.