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The Distance and Morphology of V723 Cassiopeiae (NOVA CASSIOPEIA 1995)

We present spatially resolved infrared spectra of V723 Cas (Nova Cassiopeia 1995) obtained over four years with the integral field spectrograph OSIRIS on Keck II. Also presented are one epoch of spatially unresolved spectra from the long slit spectrograph NIRSPEC on Keck II. The OSIRIS observations made use of the laser guide star adaptive optics facility that produced diffraction-limited spatial resolution of the strong coronal emission features in the nova ejecta. We remove the point-like continuum from V723 Cas data cubes to reveal details of the extended nebula and find that emission due to [Si VI] and [Ca VIII] has an equatorial ring structure with polar nodules-a strikingly different morphology than emission due to [Al IX], which appears as a prolate spheroid. The contrast in structure may indicate separate ejection events. Using the angular expansion and Doppler velocities observed over four epochs spaced at one year intervals, we determine the distance to V723 Cas to be 3.85+0.23-0.21 kpc. We present the OSIRIS three-dimensional data here in many ways: as narrowband images, one- and two-dimensional spectra, and a volume rendering that reveals the true shape of the ejecta.