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Fig. 9


Calculated line brightness temperature ratios for DCO+ 5–4/3–2, N2H+ 6–5/1–0 and c-C3H2 10–9/5–4, and 9–8/5–4. Black lines show the modeled ratios assuming column densities of 2.5 × 1012, and 1.3 × 1013 cm−2 for DCO+ and N2H+, respectively, and 7 × 1013 for both c-C3H2 ratios. Colored regions indicate the observed line ratios drawn over the range of densities and temperatures that characterize the observed emission, for IRAS 16293−2422 with ALMA (hatched blue) and VLA 1623−2417 (solid orange) with single-dish (SD) and interferometric (I) observations. For c-C3 H2, the value for IRAS 16293−2422 is from the south position.

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