Doubly substituted isotopologues of HCCCN in TMC-1: Detection of D13CCCN, DC13CCN, DCC13CN, DCCC15N, H13C13CCN, H13CC13CN, HC13C13CN, HCC13C15N, and HC13CC15N

Abstract

We report the first detection in space of a complete sample of nine doubly substituted isotopologues of HCCCN towards the cyanopolyyne peak of TMC-1 using observations of the QUIJOTE line survey taken with the Yebes 40 m telescope. We detected D13CCCN, DC13CCN, DCC13CN, DCCC15N, H13C13CCN, H13CC13CN, HC13C13CN, HCC13C15N, and HC13CC15N through their J=4-3 and J=5-4 lines in the 7 mm window. In addition, we present an extensive analysis of the emission of HCCCN and its singly substituted isotopologues through a large velocity gradient model of the lines detected at 7 mm and 3 mm using the Yebes 40 m and the IRAM 30 m telescopes, respectively. The derived column densities for all the isotopologues are consistent in the two spectral bands for an H2 volume density of 1e4 cm-3 and a kinetic temperature of 10 K. Whereas we observed a 13C fractionation for HCC13CN and other double isotopologues with a 13C atom adjacent to the nitrogen atom, we derived similar C/13C abundance ratios for the three 13C substituted species of DCCCN. This suggests additional chemical discrimination for deuterated isotopologues of HCCCN. Finally, we present the spatial distribution of the J=4-3 and J=5-4 lines from the singly substituted species observed with the Yebes 40 m telescope. The emission peak of the spatial distribution of DCCCN appears to be displaced by 40'' with respect to that of HCCCN and the 13C and 15N isotopologues. In addition to a different formation route for the deuterated species, we could also expect that this differentiation owing to the deuterium fractionation is more efficient at low temperatures, and therefore, that deuterated species trace a colder region of the cloud.

Accepted for publication in A&A

References in corpus (23)

• The importance of the ortho:para H2 ratio for the deuteration of molecules during pre-protostellar collapse
• Discovery of benzyne, o-C6H4, in TMC-1 with the QUIJOTE line survey
• Isotopic fractionation of carbon, deuterium and nitrogen : a full chemical study
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH${}_2$CN) in TMC-1
• TMC-1, the starless core sulfur factory: Discovery of NCS, HCCS, H2CCS, H2CCCS, and C4S and detection of C5S
• Discovery of HC4NC in TMC-1: A study of the isomers of HC3N, HC5N, and HC7N
• 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
• Interstellar nitrile anions: Detection of C3N- and C5N- in TMC-1
• Revised Models of Interstellar Nitrogen Isotopic Fractionation
• Discovery of the elusive thioketenylium, HCCS+, in TMC-1
• Space and laboratory observation of the deuterated cyanomethyl radical HDCCN
• Chemical nitrogen fractionation in dense molecular clouds
• Gas-grain model of carbon fractionation in dense molecular 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
• ${}^{13}$C isotopic fractionation of HC${}_3$N in two starless cores: L1521B and L134N (L183)
• Precise observations of the 12C/13C ratios of HC3N in the low-mass star-forming region L1527
• Evolutionary view through the starless cores in Taurus: deuteration in TMC 1-C and TMC 1-CP
• Detection of deuterated methylcyanoacetylene, CH${}_2$DC${}_3$N, in TMC-1
• First Detection of HC${}_5$${}^{15}$N in the Interstellar Medium
• Combined model for ${}^{15}\mathrm{N}$, ${}^{13}\mathrm{C}$, and spin-state chemistry in molecular clouds
• New deuterated species in TMC-1: Detection of CH2DC4H with the QUIJOTE line survey

Cited by in corpus (4)

• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• 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
• Isotopomer-Specific Carbon Isotope Ratio of Complex Organic Molecules in Star-Forming Cores