AAS 205th Meeting, 9-13 January 2005
Session 140 Cold Gas and Molecular Clouds
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[140.12] A Multifrequency Study of Molecular and Recombination Transitions Toward W49A

R.M. Flores, M. Lebron, A. Deshpande (NAIC)

Observations of the molecular cloud W49A with the 305-m Arecibo telescope were made across the frequency range 327 MHz to 10 GHz in order to identify molecular and recombination lines. In addition to the well-studied 1665.40 MHz and 1667.35 MHz OH masers and the 21-cm HI absorption line in the L-band, at higher frequencies (X and S-high bands) an abundance of Hydrogen and Helium recombination lines were observed. These included several high order (\Delta n > 4) transitions that were never detected before, for example, H167\eta, H157\zeta, and H172\theta. Estimates of the electron temperature (Te) from the various lines are compared to examine possible departures from local thermodynamic equilibrium. An apparent dependence of Te on \Delta n is understood as a result of systematic uncertainty in both, the line and the continuum intensities. This work was supported partly by the NAIC-REU program of NSF.

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