Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey

Abstract

We report the detection of fulvenallene ($c$-C${}_5$H${}_4$CCH${}_2$) in the direction of TMC-1 with the QUIJOTE line survey. Thirty rotational transitions with $K_a$=0,1,2,3 and $J$=9-15 were detected. The best rotational temperature fitting of the data is 9\,K and a derived column density is (2.7$\pm$0.3)$\times$10${}^{12}$ cm${}^{-2}$, which is only a factor of 4.4 below that of its potential precursor cyclopentadiene ($c$-C${}_5$H${}_6$), and 1.4--1.9 times higher than that of the ethynyl derivatives of cyclopentadiene. We searched for fulvene ($c$-C${}_5$H${}_4$CH${}_2$), a CH${}_2$ derivative of cyclopentadiene, for which we derive a 3$\sigma$ upper limit to its column density of (3.5$\pm$0.5)$\times$10${}^{12}$ cm${}^{-2}$. Upper limits were also obtained for toluene (C${}_6$H${}_5$CH${}_3$) and styrene (C${}_6$H${}_5$C${}_2$H${}_3$), the methyl and vinyl derivatives of benzene. Fulvenallene and ethynyl cyclopentadiene are likely formed in the reaction between cyclopentadiene ($c$-C${}_5$H${}_6$) and the ehtynyl radical (CCH). However, the bottom-up gas-phase synthesis of cycles in TMC-1 underestimates the abundance of cyclopentadiene by two orders of magnitude, which strengthens the need to study all possible chemical pathways to cyclisation in cold dark cloud environments, such as TMC-1. However, the inclusion of the reaction between C${}_3$H${}_3^{+}$ and C${}_2$H${}_4$ produces a good agreement between model and observed abundances.

Accepted for publication in Astronomy and Astrophysics Letters

References in corpus (17)

• Detection of Two Interstellar Polycyclic Aromatic Hydrocarbons via Spectral Matched Filtering
• The 2014 KIDA network for interstellar chemistry
• 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
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• TMC-1, the starless core sulfur factory: Discovery of NCS, HCCS, H2CCS, H2CCCS, and C4S and detection of C5S
• Discovery of two isomers of ethynyl cyclopentadiene in TMC-1: Abundances of CCH and CN derivatives of hydrocarbon cycles
• The interstellar chemistry of C3H and C3H2 isomers
• Discovery of the propargyl radical (CH2CCH) in TMC-1: one of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds
• Space and laboratory discovery of HC3S+
• Discovery of CH2CHCCH and detection of HCCN, HC4N, CH3CH2CN, and, tentatively, CH3CH2CCH in TMC-1
• Cumulene carbenes in TMC-1: Astronomical discovery of $l$-H${}_2$C${}_5$
• Discovery of C5H+ and detection of C3H+ in TMC-1 with the QUIJOTE line survey
• Space and laboratory observation of the deuterated cyanomethyl radical HDCCN
• Detection of the propargyl radical at lambda 3 mm
• Detection of deuterated methylcyanoacetylene, CH${}_2$DC${}_3$N, in TMC-1
• New deuterated species in TMC-1: Detection of CH2DC4H with the QUIJOTE line survey

Cited by in corpus (14)

• Discovery of two cyano derivatives of acenaphthylene (C${}_{12}$H${}_8$) in TMC-1 with the QUIJOTE line survey
• Discovery of the C7N- anion in TMC-1 and IRC+10216
• The magnesium paradigm in IRC+10216: Discovery of MgC${}_4$H${}^{+}$, MgC${}_3$N${}^{+}$, MgC${}_6$H${}^{+}$, and MgC${}_5$N${}^{+}$
• Discovery of two new interstellar molecules with QUIJOTE: HCCCHCCC and HCCCCS
• Aromatic cycles are widespread in cold clouds
• The spatial distribution of an aromatic molecule, C6H5CN, in the cold dark cloud TMC-1
• Discovery of thiofulminic acid with the QUIJOTE line survey: A study of the isomers of HNCS and HNCO in TMC-1
• Detection of ethanol, acetone, and propanal in TMC-1: New O-bearing complex organics in cold sources
• Detection of Interstellar $E$-1-cyano-1,3-butadiene in GOTHAM Observations of TMC-1
• Discovery of two metallic cyanoacetylides in IRC+10216: HMgCCCN and NaCCCN
• Laboratory and astronomical discovery of cyanothioketene, NCCHCS, in the cold starless core TMC-1
• Discovery of CH3CHCO in TMC-1 with the QUIJOTE line survey
• 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