All Tables

Table 1: Calculated wavelengths, Einstein coefficients (A_ij) and line strengths (S_ij) for the low-lying transitions of CH₂ (ignoring hyperfine-structure in the ortho transitions). The estimated error corresponding to the last significant figure of the calculated wavelengths is given in parenthesis. The Einstein coefficients and line strengths calculated here are half those given by Sears et al. (1984). The detected lines towards Sgr B2 are shown in bold.
Table 2: Coordinates of observed sources.
Table 3: Results of our fit of the CH lines towards Sgr B2 are given in column (A). The velocities and line widths are taken from the H I data of Garwood & Dickey (1989). Column (B) gives the previous estimates of CH column densities from the KAO measurements of Stacey et al. (1987) and columns (C) and (D) give the results from the radio $\Lambda$ -doublet lines from Genzel et al. (1979) and Andrew et al. (1978).
Table 4: Comparison of model predictions for diffuse and dense clouds with the observed abundances (compared to $2N(\rm {H_{2}})+N(\rm {H})$ ) of CH and CH₂ (X(CH) and X(CH₂)). The diffuse cloud model is for the line of sight to $\zeta$ Per (van Dishoeck & Black 1986): vDB86. The quoted density and temperature are for the centre of the cloud in the model. The dense cloud models are steady state values corresponding to the gas phase "new standard model'' of Lee et al. (1996): L96 and the gas-grain model of Ruffle & Herbst (2001): RH01 including photochemistry (P1/A at 10⁸ yr). The PDR model is for a density of 10⁵ cm^-3 and radiation field $\sim$ 650-900 times the average interstellar value (Jansen et al. 1995): J95. The observational results derived from our ISO measurements are shown as well as previous results from Lyu et al. (2001) and Hollis et al. (1995).
Table A.1: Log of the observations used.