In collaboration with Wilson, Dr Vainu Bappu showed that there is a unique relationship between the width of the ionized calcium K emission line and the absolute luminosity of a star. More recently, he has made significant contributions towards a proper understanding of this phenomenon, which has now come to be known as the Wilson-Bappu effect. His other noteworthy results relate to topics such as the behaviour of sodium emission in comets near perihelion passage as influenced by solar wind effects and the nature and growth of magnetic fields associated with the appearance of sunspots in active regions of the sun.