Bands of solid CO_2 in the 2-3 µm spectrum of S 140:IRS1

Abstract

We investigate the 2-3 µm ISO-SWS spectrum of the luminous protostellar object S 140:IRS1. Two narrow absorption features are detected at 2.70 and 2.77 μm, which are well fitted with laboratory spectra of the ν_1 + ν_3 and the 2ν_2 + ν_3 combination modes of solid . The ice in this line of sight must have been subjected to significant heating, in agreement with previously studied CO_2 bands. A combined laboratory fit to all CO2 bands detected toward S 140:IRS1 shows, among others, the need for particle shape calculations for the CO_2 stretch mode. Finally, we discuss the absence of features of isolated H_2O and dangling OH groups in the spectrum of S 140:IRS1.

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