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Near-Infrared echelle spectroscopy of Proto-Planetary Nebulae: probing the fast wind in H2

C. J. Davis·M. D. Smith·T. M. Gledhill·W. P. Varricatt
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Abstract

Echelle spectroscopy of H2, [FeII] and Br-gamma line emission from a very young planetary nebula, IRAS 21282+5050, and from four proto-planetary nebulae, IRAS 19343+2926 (M 1-92), IRAS 17150-3224 (AFGL 6815), IRAS 17423-1755 (Hen 3-1475), and IRAS 17441-2411 is presented. H2 line emission is detected in discrete shock fronts in the lobes of each nebula, regardless of source spectral type. In IRAS 17150-3224 we also uncover possible signs of rotation, as would be expected if the H2 features were excited in a magneto-centrifugal disk wind. [FeII] emission was detected in only one source, M 1-92. The H2 and [FeII] observations of M 1-92, and the complex H2 profiles in IRAS 21282+5050, are explained using the shock models of Smith and collaborators. J-type bow models are adequate in each case, i.e. a strongly-magnetised wind is not required. Finally, Br-gamma is detected in each of the five targets; in absorption in the G-type PPN though in emission in the O and B-type sources. Br-gamma emission is detected predominantly toward the near-IR continuum peak in each PPN. Low peak velocities, though very broad profile widths, are measured in each target. The emission must therefore derive from ionised regions in a fast wind very close to the central star, or, in the late-type sources, from absorption in an equatorial torus.

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C. J. Davis, M. D. Smith, T. M. Gledhill, W. P. Varricatt. 2005-03-15. Near-Infrared echelle spectroscopy of Proto-Planetary Nebulae: probing the fast wind in H2. https://doi.org/10.1111/j.1365-2966.2005.09018.x

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