0.8-13 Micron Spectroscopy of V838 Monocerotis and a Model for Its Emission
AEROSPACE CORP LOS ANGELES CA
Pagination or Media Count:
We report on the results of a number of infrared spectra 0.8-2.5, 2.1-4.6, and 3-14 microns of V838 Monocerotis, taken from a short time after discovery in 2002 January to about 14 months later, in early 2003. The spectrum evolved dramatically, changing from a quasi-photospheric stellar spectrum with weak atomic emission lines some with P Cygni profiles to one showing a wide range of deep absorption features indicative of a cool, extended atmosphere with a circumstellar dust shell. The early spectra showed lines of s-process elements, such as Sr II and Ba I. The later spectra showed absorption by gaseous H2O, CO, AlO, TiO, SiO, SO2, OH, VO, and SH, as well as a complex of emission near 10 microns reminiscent of silicate emission, with a central absorbing feature at 103 microns. Thus, V838 Mon appears to be oxygen-rich. A simple, spherically symmetric model of the system involving a central star with a two-component expanding circumstellar shell is presented that is able to explain the major molecular features and spectral energy distribution in the objects late stages. The derived shell mass and distance are 0.04 Mcircle dot solar and 9.2 kpc, respectively.
- Atomic and Molecular Physics and Spectroscopy