PI: Patrick Hartigan, Rice University, firstname.lastname@example.org
Address: Physics Department, 6100 S. Main, Houston, TX 77005, USA
Title: Dynamics Within the Collimation Region of the HH 444 Stellar Jet
Abstract: How accretion disks drive supersonic jets is one of the major unsolved problems in astrophysics. Stellar jets are ideal subjects for studying this phenomenon because they radiate optically thin forbidden emission lines that are resolved both spatially and spectrally, and these jets have measurable proper motions within a few years. When enough emission lines are observed with good S/N, new analysis techniques that make use of the strong charge exchange coupling between hydrogen, oxygen, and nitrogen make it possible to determine the ionization fractions, densities, and temperatures in jets as a function of both position and radial velocity everywhere the jet radiates. Probing physical conditions in jets throughout phase space in this manner is an extremely powerful technique, but it has not been brought to bear on this problem because the few existing observations with enough sensitvity and resolution lack the wavelength coverage needed for a complete analysis. This proposal seeks to remedy this deficit by obtaining a deep position-velocity diagram that will measure all the important optical transitions within HH 444, a jet previously observed with HIRES but over a limited spectral range. The proposed observations will provide the missing dynamical information needed to diagnose entrainment, shock heating, and possibly even reconnection in the critical zone where jets emerge from disks. In addition, enough time has now passed since the previous observations to allow us to track proper motions, and thereby learn which features in the position- velocity map of the jet evolve dynamically, and which are static.
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