DETECTION OF THE 2165 INVERSE CENTIMETER (4.619 MICRON) XCN BAND IN THE SPECTRUM OF L1551 IRS-5

We report the detection of a broad absorption band at 2165 cm-1 (4.619 mum) in the spectrum of L1551 IRS 5. New laboratory results over the 2200-2100 cm-1 wavenumber interval (4.55-4.76 mum), performed with rea listic interstellar ice analogs, suggest that this feature is due to a CN-containing compound. We will refer to this compound as XCN. We als o confirm the presence of frozen CO (both in nonpolar and polar matric es) through absorption bands at 2140 cm-1 (4.67 mum) and 2135 cm-1 (4. 68 mum). The relative abundance of solid-state CO to frozen H2O is app roximately 0.13 while the abundance of XCN seems comparable to that of frozen CO.