Detection of vibrationally excited methyl formate in W51 e2

Abstract

Context. Hot cores in molecular clouds, such as Orion KL, Sgr B2, W51 e1/e2, are characterized by the presence of molecules at sufficiently high temperatures to populate their low-frequency vibrationally excited states significantly. Complex organic molecules, such as methyl formate, ethyl cyanide or dimethyl ether, are characterized by a dense spectrum both in the ground state and in the excited states and lines from vibrationally excited states certainly participate to the spectral confusion.