NWU academic: listening to the sounds of the stars

Prof Thebe Rodney Medupe, an academic from the North-West University (NWU) campus in Mahikeng, presented his inaugural lecture, titled: "Listening to the sounds of the stars: Molodi wa di naledi", on 4 May 2017, to the Mahikeng community and astronomers alike.

Prof Medupe, a South African astrophysicist and astrophysics professor, recalled how his first encounter with astronomy at the age of 13 - the 1986 sighting of Halley's Comet - inspired him to build a crude telescope using a cardboard tube with lenses donated by a school lab technician.

Based on his field of expertise, asteroseismology, Prof Medupe's lecture was about how you study the interior physics of stars by analysing seismic waves that travel inside the stars. Detecting and measuring the many waves of different frequencies in the sun gives astronomers access to information and a better understanding of how stars work, said Prof Medupe.

"We do not detect and measure the sound waves directly, but we detect them through their effect on starlight. The waves that are generated deep inside a star may travel through to the surface, and as the wave arrives on the surface, it compresses and rarefies the gases of a star," said Prof Medupe. "The compressed gas becomes slightly hotter, and the rarefied gas cools. It is this repetitive cooling and heating of the surface gases that makes the starlight to brighten and dim in a repetitive fashion."

Prof Medupe holds an undergraduate degree in physics and a master's and doctorate in astrophysics. He initially served as a research fellow at the University of Cape Town, but returned to his home town to inspire young black South Africans to get involved in the science and study of astronomy.

"Part of my reason for doing that was to prove that the perception that black South Africans are not interested in astronomy is wrong," said Prof Medupe.

Prof Medupe has written and published numerous research papers on astronomy and, in particular, asteroseismology, contributing to national and international journals aimed at advancing the study and research thereof.

He has also made research contributions to the book: "African cultural astronomy: Current archaeoastronomy and ethnoastronomy research in Africa".