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Astron. Astrophys. 315, L189-L192 (1996)

Detection of an absorption feature at the position of the 4.27-img1.gifm band of solid CO tex2html_wrap_inline114 *

J. Gürtler1, Th. Henning2, C. Kömpe1, W. Pfau1, W. Krätschmer3, and D. Lemke4

1 Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergäßchen 2, D-07745 Jena, Germany
2 Max-Planck-Gesellschaft, Arbeitsgruppe ``Staub in Sternentstehungsgebieten'', Schillergäßchen 2-3, D-07745 Jena, Germany
3 Max-Planck-Institut für Kernphysik, Postfach 103980, D-69029 Heidelberg, Germany
4 Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany

Received 8 July 1996 / Accepted 2 August 1996

Abstract. We report observations of 13 young infrared sources associated with molecular clouds with ISO's spectrophotometer ISOPHOT-S in the wavelength range from 2.5 to 11.6 img1.gifm. In addition to a number of well-known interstellar bands due to various molecular ices, a new band at 4.27 img1.gifm was detected, which is very likely attributed to C=O stretching vibrations of solid CO2. This new band is seen in all our sources. Thus, CO2 seems to be a common constituent of icy grain mantles in molecular clouds. The strength of the band increases with the strengths of the CO and H2O bands. We estimate that CO2 and CO may be present in comparable amounts in the mantles. The implications for the models of interstellar chemistry are briefly discussed.

Key words: ISM: dust, extinction - infrared: ISM: lines and bands

* ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

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Last change: December 16, 1996
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