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T. C. Hillwig, R. K. Honeycutt (Indiana Univ. Bloomington), S. N. Shore (Indiana Univ. South Bend)
Observations of nova shells were made at the WIYN Observatory using the WIYN Imager, the ``naked'' DensePak fiber array, and a Barlow 4x magnifying assembly used with DensePak. DensePak was used to obtain spatially resolved spectra of several nova shells at wavelengths including the H\alpha, H\beta, [OIII], and [NII] emission lines.
The purpose is to derive true shapes and sizes of the nova shells, velocity structure, and abundance structure. The ability to spatially resolve the shell with spectroscopy, with the accuracy and resolution available to DensePak is a useful and unique tool.
The velocity structure of the shell provides data which can be compared to models of expected shell structure. Measuring abundances in different, spatially resolved portions of the shell can give indications of the cause of the structure. For example, in shaping by a fast wind, we may expect to see different abundances in the slowly moving ejected material than in the material comprising the fast wind (which becomes apparent in planetary nebulae with wind-blown bubbles). Imaging also provides, along with comparison to velocity structure, an additional constraint on the determination of parallax distances, and the narrow-band imaging can supply estimates of excitation levels in various regions of the shells. All of these are important contributors to the determination of the physical mechanism responsible for the nova shell structure. The first phase of this research is presented here.
The author(s) of this abstract have provided an email address for comments about the abstract: thillwig@astro.indiana.edu