Abstract
Aluminium monoxide (AlO) is widely known for its astrophysical significance. An analysis of the prominent lines of the (2,3;3,2;3,4;4,5;4,3;5,6;6,7) bands of the B 2Σ+−X 2Σ+ transition with those of sunspot umbral spectral lines suggests that the AlO molecule appears to be a non-negligible component of sunspot umbrae. Results of a recent (2008) rotational analysis were used to carry out the study. The effective rotational temperature determined for the above lines in the sunspot umbral spectrum is found to be of the order of 2900 K. The radiative-transition parameters that include Franck–Condon (FC) factors, r-centroids, electronic-transition moment, Einstein coefficient, absorption–band oscillator strength, and radiative lifetime have been estimated for the experimentally known vibrational levels using the Rydberg–Klein–Rees (RKR) potential.
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Acknowledgements
The authors express deep gratitude to their mentors N. Rajamanickam, Former Head, Physics Research Centre, VHNSN College, Virudhunagar and S.P. Bagare, Indian Institute of Astrophysics, Bangalore. We thank G. Baskaran, Research Centre in English, Gandhigram Rural Institute [Deemed University], Dindigul, for his help with language corrections. The sunspot spectra used in this study are taken from the technical reports of the National Solar Observatory, operated by the Association of Universities in Astronomy, Inc. (AURA), under a cooperative agreement with the National Science Foundation.
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Sriramachandran, P., Viswanathan, B. & Shanmugavel, R. Occurrence of AlO Molecular Lines in Sunspot Umbral Spectra. Sol Phys 286, 315–326 (2013). https://doi.org/10.1007/s11207-013-0264-1
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DOI: https://doi.org/10.1007/s11207-013-0264-1