A high-accuracy synthetic H2O line list : computation and applications
The subject matter of this Ph.D. thesis is the production and application of the Barber-Tennyson line list, BT2, a computed list of H2160 transition frequencies and intensities. BT2 was produced using a discrete variable representation two-step approach for solving the rotation-vibration nuclear motions (Tennyson et al., 2004, Comp. Phys. Comm., 163, 85). It is the most complete water line list in existence, comprising over 500 million transitions ( 65% more than any other list) and it is also the most accurate (over 90% of all known experimental energy levels are within 0.3 cm-1 of the BT2 values). Its accuracy has been confirmed by extensive testing against astronomical and laboratory data. The line list has already found application in a wide range of astrophysical en vironments. It has been used to identify individual water lines in: the spectra of comets, sunspots, cool stars, brown dwarfs and the enigmatic object V838 Mon, and in a number of cases physical parameters have been derived from the intensities of the lines. The line list has also been used to model the atmospheres of cool stars and brown dwarfs and the chemistry of the circumstellar molecular shell ejected by V838 Mon. In addition to our own work with BT2, we have supplied various data, de rived from BT2, to other astrophysical research groups including: N. Dello Russo and co-workers for cometary applications J.M.C. Rawlings for modelling the time- dependent chemistry of the shell ejected by V838 Mon and P. Hauschildt's stellar atmospheric modelling group, which has included the complete BT2 line list in its 'PHOENIX' database. Practical applications of BT2 are not confined to the field of astronomy. The line list is now the preferred reference tool for many groups engaged in the identification of water lines in high temperature laboratory torch spectra, and we have been pleased to supply them with appropriate BT2 spectral data. The final chapter of the thesis looks to the future, which includes further appli cations of BT2 and the production of an NH3 line list.