Line strengths of rovibrational and rotational transitions in the X2Î ground state of OH

- A new line list with absolute intensities for the OH Meinel system is presented.
- Ab initio and experimental data are used to produce new dipole moment function.
- Good agreement with literature O abundances in the Sun and three stars is observed.
- New partition function up to 6000K is calculated.
- The absolute intensities are more accurate than those previously available.

A new line list including positions and absolute transition strengths (in the form of Einstein A values and oscillator strengths) has been produced for the OH ground X2Π state rovibrational (Meinel system) and pure rotational transitions. All possible transitions are included with v′ and v″ up to 13, and J up to between 9.5 and 59.5, depending on the band. An updated fit to determine molecular constants has been performed, which includes some new rotational data and a simultaneous fitting of all molecular constants. The absolute transition strengths are based on a new dipole moment function, which is a combination of two high level ab initio calculations. The calculations show good agreement with an experimental v=1 lifetime, experimental μv values, and Δv=2 line intensity ratios from an observed spectrum. To achieve this good agreement, an alteration in the method of converting matrix elements from Hund׳s case (b) to (a) was made. Partitions sums have been calculated using the new energy levels, for the temperature range 5-6000 K, which extends the previously available (in HITRAN) 70-3000 K range. The resulting absolute transition strengths have been used to calculate O abundances in the Sun, Arcturus, and two red giants in the Galactic open and globular clusters M67 and M71. Literature data based mainly on [O I] lines are available for the Sun and Arcturus, and excellent agreement is found.