Discovery of the elusive thioketenylium, HCCS+, in TMC-1

Abstract

We report the detection in TMC-1 of the cation HCCS+ (3Sigma-), which is the protonated form of the widespread radical CCS. This is the first time that a protonated radical has been detected in a cold dark cloud. Twenty-six hyperfine components from twelve rotational transitions have been observed with the Yebes 40m and IRAM 30m radio telescopes. We confidently assign the characteristic rotational spectrum pattern to HCCS+ based on the good agreement between the astronomical and theoretical spectroscopic parameters. The column density of HCCS+ is (1.1+/-0.1)e12 cm-2, and the CCS/HCCS+ abundance ratio is 50+/-10, which is very similar to that of CS/HCS+ (35+/-8) and CCCS/HCCCS+ (65+/-20). From a state-of-the-art gas-phase chemical model, we conclude that HCCS+ is mostly formed by reactions of proton transfer from abundant cations such as HCO+, H3O+, and H3+ to the radical CCS.

Accepted for publication in A&A Letters on December 21st

References in corpus (13)

• The 2014 KIDA network for interstellar chemistry
• Detection of C5N- and vibrationally excited C6H in IRC +10216
• Discovery of Interstellar Propylene (CH_2CHCH_3): Missing Links in Interstellar Gas-Phase Chemistry
• Discovery of benzyne, o-C6H4, in TMC-1 with the QUIJOTE line survey
• TMC-1, the starless core sulfur factory: Discovery of NCS, HCCS, H2CCS, H2CCCS, and C4S and detection of C5S
• Space and laboratory discovery of HC3S+
• Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1
• The sulphur saga in TMC-1: Discovery of HCSCN and HCSCCH
• Tentative detection of HC5NH+ in TMC-1
• Discovery of the acetyl cation, CH3CO+, in space and in the laboratory
• Magnesium radicals MgC${}_5$N and MgC${}_6$H in IRC+10216
• Discovery of HCCCO and C5O in TMC-1 with the QUIJOTE line survey
• Interstellar detection of the simplest aminocarbyne, H2NC: an ignored but abundant molecule

Cited by in corpus (16)

• Discovery of H${}_2$CCCH${}^{+}$ in TMC-1
• Discovery of C5H+ and detection of C3H+ in TMC-1 with the QUIJOTE line survey
• Discovery of two new interstellar molecules with QUIJOTE: HCCCHCCC and HCCCCS
• The abundance and excitation of molecular anions in interstellar clouds
• Discovery of thiofulminic acid with the QUIJOTE line survey: A study of the isomers of HNCS and HNCO in TMC-1
• Discovery of a new molecular ion, HC7NH+, in TMC-1
• A new protonated molecule discovered in TMC-1: HCCNCH+
• Discovery of five cyano derivatives of propene with the QUIJOTE line survey
• Discovery of interstellar NC4NH+: dicyanopolyynes are indeed abundant in space
• Discovery of the cyclic C5H radical in TMC-1
• Laboratory and astronomical discovery of cyanothioketene, NCCHCS, in the cold starless core TMC-1
• Linking the dust and chemical evolution: Taurus and Perseus -- New collisional rates for HCN, HNC, and their C, N, and H isotopologues
• Doubly substituted isotopologues of HCCCN in TMC-1: Detection of D13CCCN, DC13CCN, DCC13CN, DCCC15N, H13C13CCN, H13CC13CN, HC13C13CN, HCC13C15N, and HC13CC15N
• Study of the HCCNC and HNCCC isotopologs in TMC-1
• CN and CCH derivatives of ethylene and ethane: Confirmation of the detection of CH${}_3$CH${}_2$CCH in TMC-1
• Synthesis and Spectroscopic Characterization of Interstellar Candidate Ethynyl Thiocyanate: HCCSCN