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R. Montez, Jr. (University of Texas at Austin), H. E. Schwarz (Cerro Tololo Inter-American Observatory), R. L. M. Corradi (Isaac Newton Group of Telescopes)
Bipolar planetary nebulae provide lasting and vivid images of the death throes of low mass stars. Their high expansion velocities, forbidden spectral emission lines and symmetric structure raise curiosity about their formation mechanism(s). Increasing the sample of definite bipolar planetary nebulae is crucial to advance the knowledge of the formation mechanism(s). The probable planetary nebula Sa2-237 has been observed with narrow-band filters to produce images and high-resolution spectra. The shape and kinematics are modeled to reveal that it is, in fact, a spectacular example of a bipolar planetary nebula. Comparisons with other bipolar planetary nebulae reveal striking similarities, which are used to infer a distance to Sa2-237 of 2.1kpc. Equipped with the distance, the kinematics and spatial modeling uncover the following properties: maximum expansion velocity of 308km/s, bolometric luminosity of 340L\sun, nebular age of 624yrs, and physical size of 0.37pc. The current data suggest that better resolution and longer exposures may yield faint and thus so far unseen high velocity material. A subsequent series of observations may result in a proper motion value due to the expansion that would give a more reliable distance and a test of the comparisons performed here. Obtaining a complete data set for Sa2-237 and similar objects is a large step toward the ultimate goal to understand the formation of this peculiar morphological class of planetary nebulae.
The author(s) of this abstract have provided an email address for comments about the abstract: rudy@astro.as.utexas.edu