Ehsan Gharib Nezhad - School of Chemistry, College of Science, University of Tehran, Tehran۱۴۱۷۶, Iran
Alireza Shayesteh - School of Chemistry, College of Science, University of Tehran, Tehran۱۴۱۷۶, Iran

Stars having remarkable emission lines in the optical spectra are called emission-line stars and widely distributed on the Hertzsprung-Russell diagram including various stellar types.۱ In addition to line positions, knowledge of Einstein A coefficients for rovibronic transitions has important applications in astrophysics.۲ Experimentally, Einstein A coefficients can be determined indirectly via lifetime measurement; however, this lifetime is related to the rate of radiative decay ofan excited state to all lower energy levels. Magnesium hydride is an important molecule in different astrophysicallyenvironments. Lines of the A۲Ȇ X۲Ȉ+transition have been detected in different stellar regions such as the solar photosphere,۳ the spectra of sunspot,۴ nearby L dwarfs,۵ and late-type stars.۶ In addition,theBƍ۲Ȉ+ X ۲Ȉ+bands have been detected in sunspot umbral spectra.۷

Line Intensities, Einstein A coefficient, MgH, Astrochemistry