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Session 121 - Molecular Clouds/Star Formation.
Oral session, Saturday, January 10
Georgetown,
We construct synthetic images and long-slit spectra of protostellar jets modeled as steady-state x-winds. Assuming uniform ionization fractions and electron temperatures, we calculate non-LTE level populations for five-level atoms. Synthetic images in the [S II]\lambda6716/6731 and [O I]\lambda6300/6364 lines have approximately the same surface brightness distribution as observed jets. Thus, observed jets may be optical illusions at their base, since x-winds become highly focused only at large distances from the source. Long-slit spectra taken with the slit placed along the central axis of the jet, or slightly diplaced from it, provide strong evidence in support of the x-wind theory. In both the models and the actual objects, wide line-profiles, containing both large positive and negative velocities, are often seen at the base of the flow, indicative of a wide-angle wind. As one progresses uo the length of the slit, the line profiles narrow to straddle the projected velocity of a well-collimated jet.
