• DOI:10.1051/0004-6361/202245018
• Corpus ID: 253018729

Discovery of two new interstellar molecules with QUIJOTE: HCCCHCCC and HCCCCS

@article{Fuentetaja2022DiscoveryOT,
  title={Discovery of two new interstellar molecules with QUIJOTE: HCCCHCCC and HCCCCS},
  author={Ra'ul Fuentetaja and Marcelino Ag'undez and Carlos Cabezas and Bel{\'e}n Tercero and N. Marcelino and Juan R. Pardo and Pablo de Vicente and Jos{\'e} Cernicharo},
  journal={Astronomy \& Astrophysics},
  year={2022}
}

• R. Fuentetaja, M. Ag'undez, +5 authors J. Cernicharo
• Published 20 October 2022
• Physics, Chemistry
• Astronomy & Astrophysics

We report on the discovery of two new molecules, HCCCHCCC and HCCCCS, towards the starless core TMC-1 in the Taurus region from the QUIJOTE line survey in the 31.1-50.2 GHz frequency range. We identify a total of twenty-nine lines of HCCCHCCC and six rotational transitions of HCCCCS. The rotational quantum numbers range from J u = 10 up to 15 and K a ≤ 2 for HCCCHCCC and J u = 21 / 2 up to 31 / 2 for HCCCCS. We derived a column density for HCCCHCCC of N = (1.3 ± 0.2) × 10 11 cm − 2 with a rotational temperature of 6 ± 1 K, while for HCCCCS we derived N = (9.5 ± 0.8) × 10 10 cm − 2 and T rot = 10 ± 1 K. The abundance of HCCCHCCC is higher than that of its recently discovered isomer, l-H 2 C 6 . If we compare HCCCCS with its related molecules, HCS and HCCS, we obtain abundance ratios HCS / HCCCCS = 58 and HCCS / HCCCCS = 7.2. We investigated the formation of these two molecules using chemical modelling calculations. The observed abundances can be accounted for by assuming standard gas-phase formation routes involving neutral-neutral reactions and ion-neutral reactions.