.oh / Ir Source Oh Maser Infrared Radiation Pumped Absorption Lines

The bright OH masers are excellent probes of different kinds of astronomical objects in the Galaxy and even of distant galaxies, but the difficulties in identifying the pumping mechanisms of these OH masers and modeling them have hindered the application of this excellent probe. One of the critical point for solving this problem is to effectively identify the pumping mechanisms of known OH masers and find out the physical connections between the masers and the objects bearing these masers. This thesis has utilized the high-quality and high-resolution infrared spectra obtained by Infrared Space Observatory (ISO) to study the disciplinarian of the presence of the radiative pumping lines of the OH 1612MHz masers and the characteristics of their spectral profiles. A phenomenological method was also invoked to compare among the radiative pumping lines in infrared, the maser emission in microwave and other physical properties of the maser sources. Such analysis shows that: (1) Some OH masers are confirmed of their radiative pumping mechanism while some other OH masers might be pumped by other mechanisms, and for another set of OH masers whose radiative pumping lines which is expected by our estimation based on modeling work are not detected, which may be due to other reasons such as clumpy OH shell and limb filling emission effect. (2) Red supergiants and AGB stars show a blue-shifted filling emission feature in their 53.3μm absorption line profile while H II regions show a red-shifted filling emission feature. The explanation preferred by this thesis is as this: The 53.3um absorption line is a doublet, and hence the blue- or red-shifted filling emission feature might be the manifestation of a weaker absorption or even emission in one component of the doublet (blue or red). The main conclusions from the works presented in this thesis can be as this: for the Galactic OH 1612MHz masers, the radiative pumping mechanism coexists with other mechanisms while some other unresolved problems need to be solved after the launch of more advanced space infrared spectrometer and the more reliable identification of the evolutionary status of the maser bearing infrared sources; the asymmetrical 53.3μm absorption line profile could become a powerful tool to assist us to observationally discriminate the radiative pumping mechanism from other pumping mechanisms in the OH masers.This is the English version of my PhD thesis. There is another Chinese version for the convenience of Chinese speaking readers to read.