# $^{12}C/^{13}C$ RATIOS IN MOLECULAR CLOUDS AND AGB STARS FROM MILLIMETER TRANSITIONS OF CN

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 dc.creator Milam, Stefanie N. en_US dc.creator Savage, Chandra en_US dc.creator Ziurys, L. M. en_US dc.creator Apponi, A. J. en_US dc.creator Wyckoff, S. en_US dc.date.accessioned 2006-06-15T20:50:12Z dc.date.available 2006-06-15T20:50:12Z dc.date.issued 2004 en_US dc.identifier 2004-RD-07 en_US dc.identifier.uri http://hdl.handle.net/1811/21280 dc.description Author Institution: Department of Chemistry, Department of Astronomy, Steward Observatory, University of Arizona; Department of Physics and Astronomy, Arizona State University en_US dc.description.abstract Observations of the $^{12}CN$ and $^{13}CN N=1\rightarrow 0$ (113 and 109 GHz) and $N=2\rightarrow 1$ (227 and 217 GHz) transitions have been conducted towards both molecular clouds and circumstellar envelopes of AGB stars, using the ARO 12m telescope on Kitt Peak, AZ. These measurements are being used to establish $^{12}C/^{13}C$ ratios, and are an extension of previous work done by Savage et al. in molecular clouds (2002, ApJ, 578, 211). Unlike CO and $H_{2}CO, ^{14}N$ and $^{13}C$ hyperfine structure of CN can be used to establish optical depths and hence accurate isotope ratios. Observations towards various clouds such as S156, G35.2 and G29.9 in both the $N=1\rightarrow 0$ and the $N=2\rightarrow 1$ transitions are consistent with a linear increase in the $^{12}C/^{13}C$ ratio as a function of distance from the galactic center. The AGB study is currently underway and will be used to test models of stellar nucleosynthesis and examine possible correlations between the ratios in clouds vs. stellar envelopes. en_US dc.format.extent 300482 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title $^{12}C/^{13}C$ RATIOS IN MOLECULAR CLOUDS AND AGB STARS FROM MILLIMETER TRANSITIONS OF CN en_US dc.type article en_US