of HC$_3$N is traced by the emission of the $J=10-9$ line in a map with an angular resolution of $1{\mbox{\rlap{.}$''$}}08\times0{\mbox{\rlap{.}$''$}}81$ and a rms per 3 km s$^{-1}$ channel of 0.9 mJy beam$^{-1}$, while the distribution of HC$_5$N is illustrated by the emission of the $J=32-31$ line, with an angular resolution of $1{\mbox{\rlap{.}$''$}}11\times0{\mbox{\rlap{.}$''$}}99$ and a rms per 3 km s$^{-1}$ channel of 0.6 mJy beam$^{-1}$.

![image](fig_map_superimposed){width="78.00000%"}

**C$_6$H.** The radical hexatriynyl, C$_6$H, has a plethora of rotational transitions in the $\lambda~3$ mm spectrum of IRC+10216, consisting of two series of doublets arising from the $^2\Pi_{1/2}$ and $^2\Pi_{3/2}$ spin-orbit fine structure states, the former lying 21.6 K above the latter. Due to the lower sensitivity of the interferometric data of each individual line, we only considered ALMA data obtained with the compact configuration and stacked the maps of a selected list of 19 lines, all free of blending and observed with a sufficient quality, to obtain a more sensitive map of the spatial distribution of C$_6$H (see Fig. \[fig:map\_all\]). Because we have omitted the ALMA data obtained with the extended configuration, the angular resolution of the C$_6$H map is of the order of $\sim$3$''$, i.e., significantly poorer than in the rest of maps 