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Astron. Astrophys. 317, L43-L46 (1997)

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Letter to the Editor

Further evidence for the [FORMULA] assignment to the XCN band
in astrophysical ice analogs

W.A. Schutte and J.M. Greenberg

Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands

Received 7 July 1995 / Accepted 22 October 1996


The well-known "XCN" feature near 2167 [FORMULA] observed towards various low- and high-mass embedded protostars can be well matched with a feature produced by photolysis of astrophysical ice analogs containing CO and [FORMULA]. An assignment of this laboratory XCN band to [FORMULA] was earlier proposed based on the correspondence in position and in the [FORMULA] and [FORMULA] isotopic shifts, We report here a further experimental study of this identification. First, the isotope shift of the XCN band obtained by irradiating [FORMULA] labelled ice samples equals 8.7 [FORMULA] 0.6 [FORMULA], in good agreement with [FORMULA]. Second, highly sensitive spectroscopy reveals three additional weak features which can be assigned to the [FORMULA] ion. Together with the earlier work, these results leave little doubt to the correctness of the identification of the laboratory XCN feature with [FORMULA].

Key words: ISM: clouds — ISM: dust, extinction — ISM: molecules — stars: pre-main-sequence

Send offprint requests to: W.A. SCHUTTE

© European Southern Observatory (ESO) 1997