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Fig. 22

image

Ratio of the brightness temperatures of 12CO(1–0) and 13CO(1–0), 12C/13C isotopic ratio, and optical depth of line 12CO(1–0) against the distance to the star (blue squares, red triangles and black circles, respectively). The continuous blue curve is the brightness temperature ratio calculated with MADEX and the kinetic temperature derived in Sect. 4.3.1. The 1σ uncertainties have been plotted as vertical bars, a grey region, or a hatched rectangle.

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