1. Birla Institute of Technology and Science-Pilani, Hyderabad Campus , Hyderabad 500078 , India
2. Department of Mathematical and Physical Sciences, College of Arts and Sciences, University of Nizwa ,Nizwa 616, Oman
3. Department of Physics, National Defence Academy , Khadakwasla, Pune 411023 , India
4. Astrophysics Research Centre, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal , Private Bag X54001, Durban 4000 , South Africa