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J. Fuentes Lettura (Universidad de La Serena (ULS) and CTIO), H. Schwarz, H. Monteiro, A. Whiting (CTIO)
We present a study of five Planetary Nebulae (PNe) that maybe interacting with the Inter-Stellar Medium (ISM). Three of these nebulae clearly have their central star displaced from the center of the object, indicating interaction. Images from the CTIO 0.9m telescope and low resolution long slit spectra in the range 358-698nm taken with the RC spectrograph on the CTIO 1.5m telescope during February 2004 were obtained. From the spectra we extracted 37 emission lines which were then used to compute the reddening, electron temperatures and densities, some chemical abundances (O, N, Ne, S & Ar) for each of our PNe. We also made an attempt at calculating their distances using the method of comparing forbidden line fluxes with those of recombination lines taking into account some estimate of the filling factor by analysing the structure in the images, but we are forced to conclude that these distances are very uncertain.
The possible --and even likely in the case of ISM interaction-- presence of shocks would affect the abundance determinations, making their uncertainty larger.
Key words: Old Planetary Nebulae - Chemical abundances - Interaction with the ISM
Acknowledments. I would like to thank CTIO for the opportunity to develop this work as part of the Programa de Investigación en Astronom\'{i}a (PIA) for Chilean students. This research was supported in part by the National Science Foundation (NSF) through the CTIO REU/PIA program.
The author(s) of this abstract have provided an email address for comments about the abstract: jfuentes@dfuls.cl
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.