Consistent system of oscillator strengths of A$^{2}\Delta$ -- X$^{2}\Pi$ (0, 0) and B$^{2}\Sigma^{-}$ -- X$^{2}\Pi$ (0, 0) bands of CH molecule

Abstract

Detailed analysis of intensity ratios of unsaturated methylidyne (CH) A--X and B--X bands suggests consistency of the recently published oscillator strengths of A$^{2}\Delta$ -- X$^{2}\Pi$ (0, 0) -- 4300 \AA\ and B$^{2}\Sigma^{-}$ -- X$^{2}\Pi$ (0, 0) -- (3878, 3886 and 3890 \AA) bands (ie. 506, 107, 320 and 213$\times$10$^{-5}$ respectively). This result is based on extremely high S/N ratio spectra of 45 stars, acquired with three high-resolution spectrographs, situated in Chile: ESO LaSilla (HARPS), ESO Paranal (UVES) and Las Campanas (MIKE) and MAESTRO instrument situated in Northern Caucasus (Russia). The calculated methylidyne column densities, obtained using the consistent system of the oscillator strengths toward the observed targets, are given as well. We verify oscillator strengths of the CH+ A-X (0, 0) and (0, 1) bands at 4232 \AA\ and 3957 \AA\ equal to 545 and 342$\times$10$^{-5}$ respectively. We also confirm the lack of correlation between abundances of neutral CH and CH$^{+}$ which the fact demonstrates that they are originated in different environments.