On the requirement for a high resolution spectrograph to investigate the multiplicity of massive stars with the 3.6-m Devasthal Optical Telescope

The investigation of the multiplicity of massive stars constitutes a key aspect of their understanding. On the one hand, the evolution of short period systems can be tremendously influenced by the companion, for instance through mass exchange or common envelope evolution. On the other hand, the wind-wind interaction region in massive multiple systems is the seat of a high level physics, including strong thermal X-ray emission, particle acceleration and non-thermal emission processes. The description and understanding of these processes require the accurate determination of orbital parameters, notably through spectroscopic studies. In this context, it is timely to anticipate some relevant applications of a high resolution spectrograph (HRS) to be mounted on the Devasthal Optical Telescope, emphasizing its potential complementarity with other Indian facilities such as the GMRT and Astrosat.