%0 Journal Article
%T First detection of [13C£¿II] in the Large Magellanic Cloud
%A Cristian Guevara
%A J¨¹rgen Stutzki
%A Marc Mertens
%A Ronan Higgins
%A Volker Ossenkopf-Okada
%A Yoko Okada
%J -
%D 2019
%R 10.1051/0004-6361/201936685
%X <i>Context.<i/> [<sup>13<sup/>C£¿II] observations in several Galactic sources show that the fine-structure [<sup>12<sup/>C£¿II] emission is often optically thick (the optical depths around 1 to a few).<i>Aims.<i/> Our goal was to test whether this also affects the [<sup>12<sup/>C£¿II] emission from nearby galaxies like the Large Magellanic Cloud (LMC).<i>Methods.<i/> We observed three star-forming regions in the LMC with upGREAT on board SOFIA at the frequency of the [C£¿II] line. The 4 GHz bandwidth covers all three hyperfine lines of [<sup>13<sup/>C£¿II] simultaneously. For the analysis, we combined the [<sup>13<sup/>C£¿II] F = 1£¿0 and F = 1£¿1 hyperfine components as they do not overlap with the [<sup>12<sup/>C£¿II] line in velocity.<i>Results.<i/> Three positions in N159 and N160 show an enhancement of [<sup>13<sup/>C£¿II] compared to the abundance-ratio-scaled [<sup>12<sup/>C£¿II] profile. This is likely due to the [<sup>12<sup/>C£¿II] line being optically thick, supported by the fact that the [<sup>13<sup/>C£¿II] line profile is narrower than [<sup>12<sup/>C£¿II], the enhancement varies with velocity, and the peak velocity of [<sup>13<sup/>C£¿II] matches the [O£¿I] 63 <i>¦Ì<i/>m self-absorption. The [<sup>12<sup/>C£¿II] line profile is broader than expected from a simple optical depth broadening of the [<sup>13<sup/>C£¿II] line, supporting the scenario of several PDR components in one beam having varying [<sup>12<sup/>C£¿II] optical depths. The derived [<sup>12<sup/>C£¿II] optical depth at three positions (beam size of 14¡å, corresponding to 3.4 pc) is 1£¿3, which is similar to values observed in several Galactic sources shown in previous studies. If this also applies to distant galaxies, the [C£¿II] intensity will be underestimated by a factor of approximately 2
%U https://www.aanda.org/articles/aa/full_html/2019/11/aa36685-19/aa36685-19.html