Radiative transition probabilities, lifetimes and the vibrational temperature for the astrophysical molecule CaF

With the purpose of providing the spectroscopic parameters that can contribute to future identification of calcium fluoride (CaF) molecule in sunspot, interstellar and circumstellar environments, the present work by focusing mainly on the astrophysically significant molecule CaF, provides the qualitative study of i) the transition probability parameters like Franck-Condon factors and r-centroids for the electronic transitions C-X, D-X, E-X, C-B, C-B' and E'-A and ii) the transition moment, oscillator strength, Einstein coefficients, vibrational temperature and radiative lifetimes of the higher electronic state E, using the derived transition probability parameters for E-X transition. The evaluated transition probability parameters reveal the astrophysical importance of CaF molecular transitions and they are discussed elaborately using the spectroscopic technique. Based on the present calculations, radiative lifetimes for the vibrational levels from 1 to 5 for the state E are predicted to be 14.0, 21.9, 36.1, 82.8, 97.0 ns respectively and it is found that the calculated values are in excellent agreement with the experimental results reported earlier. The observed vibrational temperature of 1451 ± 134 K for the electronic transition E-X also favors the prediction of the existence of CaF molecule in cold sunspot.