13C-methyl formate: observations of a sample of high mass star-forming regions including Orion-KL and spectroscopic characterization

Abstract : We have surveyed a sample of massive star-forming regions located over a range of distances from the Galactic centre for methyl formate, HCOOCH$_{3}$, and its isotopologues H$^{13}$COOCH$_{3}$ and HCOO$^{13}$CH$_{3}$. The observations were carried out with the APEX telescope in the frequency range 283.4--287.4~GHz. Based on the APEX observations, we report tentative detections of the $^{13}$C-methyl formate isotopologue HCOO$^{13}$CH$_{3}$ towards the following four massive star-forming regions: Sgr~B2(N-LMH), NGC~6334~IRS~1, W51 e2 and G19.61-0.23. In addition, we have used the 1~mm ALMA science verification observations of Orion-KL and confirm the detection of the $^{13}$C-methyl formate species in Orion-KL and image its spatial distribution. Our analysis shows that the $^{12}$C/$^{13}$C isotope ratio in methyl formate toward Orion-KL Compact Ridge and Hot Core-SW components (68.4$\pm$10.1 and 71.4$\pm$7.8, respectively) are, for both the $^{13}$C-methyl formate isotopologues, commensurate with the average $^{12}$C/$^{13}$C ratio of CO derived toward Orion-KL. Likewise, regarding the other sources, our results are consistent with the $^{12}$C/$^{13}$C in CO. We also report the spectroscopic characterization, which includes a complete partition function, of the complex H$^{13}$COOCH$_{3}$ and HCOO$^{13}$CH$_{3}$ species. New spectroscopic data for both isotopomers H$^{13}$COOCH$_{3}$ and HCOO$^{13}$CH$_{3}$, presented in this study, has made it possible to measure this fundamentally important isotope ratio in a large organic molecule for the first time.
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Astrophysical Journal Supplement, American Astronomical Society, 2014, 215 (2), pp.id. 25
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https://hal.archives-ouvertes.fr/hal-01076453
Contributeur : Marie-Paule Pomies <>
Soumis le : mercredi 22 octobre 2014 - 11:17:59
Dernière modification le : mercredi 12 octobre 2016 - 01:22:22

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C. Favre, Carvajal Miguel, Field David, Jorgensen Jes, Bisschop Suzanne, et al.. 13C-methyl formate: observations of a sample of high mass star-forming regions including Orion-KL and spectroscopic characterization. Astrophysical Journal Supplement, American Astronomical Society, 2014, 215 (2), pp.id. 25. <hal-01076453>

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