All Tables

Table 1: Transitions, frequencies, upper level energies ( $E_{\rm up}$ ) and Einstein A coefficients ( $A_{\rm ul}$ ) of the observed lines.
Table 2: Sample of sources.
Table 3: Observed line fluxes ( $W=\int T_{\rm MB}~ {\rm d}V$ in K km s^-1), line widths ( $\Delta V$ in km s^-1) and opacities for the CN 3 $5\over 2$ -2 $3\over 2$ transitions. The frequencies are given in GHz. Upper limits are at $3\sigma$ in line flux. Numbers in brackets are uncertainties in units of the the last decimal place. The line width was taken to be fixed with an estimated error of $\lesssim$ 30%.
Table 4: Observed line fluxes ( $W=\int T_{\rm MB}~ {\rm d}V$ in K km s^-1), line widths ( $\Delta V$ in km s^-1) and opacities for the CN 3 $7\over 2$ -2 $5\over 2$ transitions. The frequencies are given in GHz. Upper limits are at $3\sigma$ in line flux. Numbers in brackets are uncertainties in units of the the last decimal place. The hyperfine line widths were taken to be fixed with an estimated error of $\lesssim$ 30%.
Table 5: Observed line fluxes ( $W=\int T_{\rm MB}~ {\rm d}V$ in K km s^-1) and line widths ( $\Delta V$ in km s^-1) for the NO, CO⁺ and SO⁺ transitions. The frequencies are given in GHz. Upper limits are at $3\sigma$ in line flux. Numbers in brackets are uncertainties in units of the the last decimal place. The hyperfine line widths of NO were taken to be fixed with an estimated error of $\lesssim$ 30%.
Table 6: Inferred abundances from radiative transfer models assuming constant radial abundances.
Table 7: Inferred inner abundances $x_{\rm 100~K}$ from jump models assuming the emission to come from the region with $T\gtrsim 100$ K. The average temperature $T_{\rm av}$ , hydrogen density $n_{\rm H,~ av}$ and size (radius) of the inner 100 K region are also given.
Table 8: Inferred inner abundances $x_{\rm XDR}$ from jump models assuming the emission to come from the X-ray dominated inner 1000 AU envelope. The average temperature $T_{\rm av}$ and hydrogen density $n_{\rm H,~ av}$ of the inner 1000 AU region are also given.
Table 9: Observed abundance ratios assuming constant abundances.
Table 10: Observed fractional abundances from literature.
Table 11: Summary of processes predicted to be involved in the formation of each molecule.
Table 12: Estimates of the X-ray luminosity in low-mass objects from the observed CN abundances.
Table A.1: Column densities $N({\rm CO^+})$ and fractional abundances $x({\rm CO^+})$ calculated with Eq. (A.1) assuming $T_{\rm ex}({\rm CO^+}) = 20$ K. The upper limits correspond to $3\sigma$ in line flux.
Table B.1: Assumed initial abundances and cosmic-ray ionization rate for the chemical models (Figs. B.1-10).
Table B.2: Summary of the results from the general parameter study*.