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Session 41 - Jets and Outflows from YSOs.
Display session, Tuesday, June 11
A self-consistent procedure is outlined for determining the thermal structure of gas inflowing along magnetic field lines of a young stellar object. A young pre--main- sequence star (e.g., classical T Tauri star or Herbig Ae/Be star) is assumed to possess a dipole magnetic field which disrupts a geometrically thin accretion disk and channels the incoming gas toward the stellar surface, leading to the formation of an accretion funnel which terminates in a shock at a high stellar latitude. By solving the heat equation coupled to rate equations for hydrogen, the main physical processes which heat and cool the gas are identified. The aforementioned model of accretion has recently become quite attractive for classical T Tauri stars. Using fiducial parameters for these low-mass stars, the thermal structure is calculated and it is shown that the principle heat source in the accretion funnel is adiabatic compression; whereas the main coolants include bremsstrahlung radiation and line emission from the Ca II and Mg II ions. The observational consequences of this model as applied to classical T Tauri stars are presented. Finally, the calculational procedure is applied to Herbig Ae/Be stars, where the radiation field from the central star is considerably stronger than for the previous case. The results of these calculations are discussed and contrasted with the lower luminosity case.
Program listing for Tuesday