Discovery of C5H+ and detection of C3H+ in TMC-1 with the QUIJOTE line survey

Abstract

We report the discovery of the C5H+ cation toward TMC-1 with the QUIJOTE line survey. Four lines from J=7-6 up to J=10-9 have been identified in perfect harmonic frequency relation that can be fit with B=2411.94397 +/-0.00055 MHz and D=138+/-3 Hz. The standard deviation of the fit is 4.4 kHz. After discarding potential candidates, C5H- among them, we conclude that the carrier is C5H+, for which accurate ab initio calculations provide B=2410.3 MHz. We also report for the first time in a cold starless core the detection of the C3H+ cation. The column densities we derive for C5H+ and C3H+ are (8.8+/-0.5)e10 cm-2 and (2.4+/-0.2)e10 cm-2, respectively. Hence, the C5H+/C3H+ abundance ratio is 3.7+/-0.5. The fact that C5H+ is more abundant than C3H+ is well explained by dedicated chemical models and is due to the slow reactivity of C5H+ with H2, while C3H+ reacts with H2.

Accepted for publication in A&A Letters on January 5th

References in corpus (18)

• Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene and indene
• Detection of C5N- and vibrationally excited C6H in IRC +10216
• Discovery of benzyne, o-C6H4, in TMC-1 with the QUIJOTE line survey
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• The chemistry and spatial distribution of small hydrocarbons in UV-irradiated molecular clouds: the Orion Bar PDR
• The interstellar chemistry of C3H and C3H2 isomers
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• Spatially resolved l-c3h+ emission in the horsehead photodissociation region: Further evidence for a top-down hydrocarbon chemistry
• Space and laboratory discovery of HC3S+
• Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1
• Interstellar nitrile anions: Detection of C3N- and C5N- in TMC-1
• The sulphur saga in TMC-1: Discovery of HCSCN and HCSCCH
• Tentative detection of HC5NH+ in TMC-1
• Discovery of the elusive thioketenylium, HCCS+, in TMC-1
• Discovery of the acetyl cation, CH3CO+, in space and in the laboratory
• New molecular species at redshift z=0.89
• Interstellar detection of the simplest aminocarbyne, H2NC: an ignored but abundant molecule
• A CSO Search for $l$-C${}_3$H${}^{+}$: Detection in the Orion Bar PDR

Cited by in corpus (12)

• Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
• Carbon-Chain Chemistry in the Interstellar Medium
• Astronomical Detection of the Interstellar Anion C10H- towards TMC-1 from the GOTHAM Large Program on the GBT
• Discovery of H${}_2$CCCH${}^{+}$ 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
• A search for the three isomers of cyano-1,3-butadiene in TMC-1: Implications for bottom-up routes involving 1,3-butadiene
• 3 mm Spectroscopic Observations of Massive Star-Forming Regions with IRAM 30-m
• Spectral survey of the diffuse gas toward BL Lac in the Q band
• Chemistry of Dark Molecular Clouds