Abstract
An observational study of chemical abundances in the galactic planetary nebulae NGC 1535, NGC 2438, NGC 2440, NGC 3132, NGC 3242, NGC6302, and NGC 7009 based on long-slit spectra of high signal-to-noise ratio in the 3100 to 6900 A range is presented. We determined the N, O, Ne, S, and Cl abundances from collisionally excited lines and the He and O ++ abundances from recombination lines. The O ++ /H + estimates derived from recombination lines are about a factor of four and two higher than those derived from forbidden lines for NGC 7009 and NGC 3242, respectively. Spatial profiles of O ++ /H + abundance from OII permitted lines and from [OIII] forbidden lines were obtained for the planetary nebula NGC 7009. The differences between O ++ /H + derived from recombination and from forbidden lines present smooth variations along the nebular surface of NGC 7009, with the differences decreasing from the center to the edges of the nebula. If these abundance differences are explained by the presence of electron temperature fluctuations, quantified by the parameter t 2 , a value of about t 2 = 0.09 is required for NGC 3242 and NGC 7009.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
