The infrared band strengths of CH3OH, NH3 and CH4 in laboratory simulations of astrophysical ice mixtures
نویسنده
چکیده
Results from groundbased observations and the Infrared Space Observatory (ISO) indicate that CH3OH, NH3 and CH4 are important constituents of interstellar ice mantles. In order to accurately calculate the column densities of these molecules, it is important to have good measurements of their infrared band strength in astrophysical ice analogs. Band strength measurements of CH3OH and CH4 are presented showing that they depend only weakly on the composition of the ice matrix and the temperature. On the other hand, the umbrella mode of NH3 does show a significant decrease when dilluted in H2O ice. For this reason the original estimates of the abundance of NH3 in interstellar ice need to be revised upward by 30%.
منابع مشابه
Laboratory studies of thermally processed H2O-CH3OH-CO2 ice mixtures and their astrophysical implications
Data of the Infrared Space Observatory ISO have strongly influenced the current view of interstellar ice chemistry. ISO and ground-based results have confirmed that the most abundant ice species in warm regions close to massive protostars are H2O, CO2, and CH3OH. Ice segregation in those environments reflects the extensive thermal processing of grains over the lifetime of protostars. We present...
متن کاملUnraveling the 10 micron "silicate" feature of protostars: the detection of frozen interstellar ammonia.
We present infrared spectra of four embedded protostars in the 750-1230 cm-1 (13.3-8.1 microns) range. For NGC 7538 IRS 9, a new band is reported at 1110 cm-1 (9.01 microns, and several others may be present near 785, 820, 900, 1030, and 1075 cm-1 (12.7, 12.2, 11.1, 9.71, and 9.30 microns). The band 1110 cm-1 is attributed to frozen NH3. Its position and width imply that the NH3 is frozen in...
متن کاملVariations in the strength of the infrared forbidden 2328.2 cm-1 fundamental of solid N2 in binary mixtures.
We present the 2335-2325 cm-1 infrared spectra and band positions, profiles and strengths (A values) of solid nitrogen and binary mixtures of N2 with other molecules at 12 K. The data demonstrate that the strength of the infrared forbidden N2 fundamental near 2328 cm-1 is moderately enhanced in the presence of NH3, strongly enhanced in the presence of H2O and very strongly enhanced (by over a f...
متن کاملThe surface compositions of Pluto and Charon
The surface of Pluto as it is understood on the eve of the encounter of the New Horizons spacecraft (mid-2015) consists of a spatially heterogeneous mix of solid N2, CH4, CO, C2H6, and an additional component that imparts color, and may not be an ice. The known molecular ices are detected by near-infrared spectroscopy. The N2 ice occurs in the hexagonal crystalline b-phase, stable at T > 35.6 K...
متن کاملSpectroscopic constraints on CH3OH formation: CO mixed with CH3OH ices towards young stellar objects
The prominent infrared absorption band of solid CO – commonly observed towards young stellar objects (YSOs) – consists of three empirically determined components. The broad ‘red component’ (2136 cm−1, 4.681 μm) is generally attributed to solid CO mixed in a hydrogenbonded environment. Usually, CO embedded in the abundantly present water is considered. However, CO:H2O mixtures cannot reproduce t...
متن کامل