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Session 5 - Accretion and Outflows in YSOs.
Display session, Wednesday, January 07
The optical and near IR nebulae associated with protostars are believed to be formed by starlight scattering off dust particles in infalling circumstellar envelopes. Including cavities in these envelopes has enabled the modeling of scattered light images of many objects. The cavities are believed to be formed by the strong jets and outflows associated with young stellar objects. How the jet interacts with the envelope and sculpts the resulting cavities is uncertain. Motivated by recent observations, we present model scattered light images of three different cavity shapes --- bubbles, curved cavities, and streamline cavities. These different shapes occur at different ages of a protostar. The notion is that the jets initially produce bipolar bubbles in the envelope. Through time, and multiple jet outbursts, the jet bursts through the bubble leaving dust lined curved cavities. For older sources the cavity shapes are streamlines of the infalling particles in the envelope. We present optical and near IR model images of these three systems for various viewing angles. Applying this sequence to HL Tauri, we find that the bubble scenario best matches the scattered light images and polarization, indicating that HL Tauri is a very young protostar.
Program listing for Wednesday