http://arxiv.org/abs/2108.01480
After the previous discovery of MgC$_3$N and MgC$_4$H in IRC+10216, a deeper Q-band (31.0-50.3 GHz) integration on this source had revealed two additional series of harmonically related doublets that we assigned on the basis of quantum mechanical calculations to the larger radicals MgC$_5$N and MgC$_6$H. The results presented here extend and confirm previous results on magnesium-bearing molecules in IRC\,+10216. We derived column densities of (4.7$\pm$1.3)$\times$10$^{12}$ for MgC$_5$N and (2.0$\pm$0.9)$\times$10$^{13}$ for MgC$_6$H, which imply that MgC$_5$N/MgC$_3$N=0.5 and MgC$_6$H/MgC$_4$H = 0.9. Therefore, MgC$_5$N and MgC$_6$H are present with column densities not so different from those of the immediately shorter analogs. The synthesis of these large magnesium cyanides and acetylides in IRC+10216 can be explained for their shorter counterparts by a two-step process initiated by the radiative association of Mg$^+$ with large cyanopolyynes and polyynes, which are still quite abundant in this source, followed by the dissociative recombination of the ionic complexes.
J. Pardo, C. Cabezas, J. Fonfría, et. al.
Wed, 4 Aug 21
15/66
Comments: 5 pages, 3 figures