Towards radial velocity measurements with iodine absorption cell on VBT Echelle Spectrograph

Abstract

Essentially all information about astronomical objects outside the solar system reach us via light, i.e., the electromagnetic radiation. White light is composed of many wavelengths which are not resolved into their different colors. Monitoring white light gives the positions of objects in the night sky. It can be used to construct maps of stars and galaxies and also be used to plot the movements of heavenly bodies such as comets through the night sky. Using instruments with low resolving power, it is possible to separate the light arriving at Earth into broad band colors. Colors of celestial bodies give information about their temperature. For example, blue stars are hotter than red ones; objects that emit X-rays, such as the solar corona, are very hot, whereas cold objects may only emit light of very long wavelengths such as radio waves. The most detailed astrophysical information is only obtained from high- resolution studies which involve detecting the light arriving at the earth as a function of its component wavelengths.