AAS 201st Meeting, January, 2003
Session 77. The Interstellar Medium II
Poster, Wednesday, January 8, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[77.07] CN/HCN: A Global Indicator of Star Formation?

T.A.D. Paglione (York College, CUNY), J.M. Jackson (Boston Univ.), E.A. Bergin (CfA)

We present a high resolution map of the CN N=1-0, J=3/2-1/2 emission from the nearby starburst galaxy NGC 253. Our goal is to study how the global characteristics of galaxies, such as, in this case, the ambient radiation field, affect their large-scale molecular emission. We compare the CN map to our existing HCN and CO images of NGC 253. The ratio of CN and HCN intensities, which can change by orders of magnitude from cloud core to edge, is a sensitive probe of optical depth, the radiation field and photochemical processes. Using models of cloud chemistry and molecular excitation, we estimate the properties of the clouds and the effect of the unusual stellar population in the starburst nucleus of NGC 253. We also compare these data to our maps of CN, HCN and CO over the same spatial scales in the Milky Way. The median value of I(CN)/I(HCN) in NGC 253 is ~0.8, compared to the median value of ~0.3 in the Galaxy. The effect of the starburst and/or the active nucleus of NGC 253 is apparent in this elevated ratio.

The author(s) of this abstract have provided an email address for comments about the abstract: paglione@york.cuny.edu

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