INDIRECT SEARCHES: DOPPLER SPECTROSCOPY AND PULSAR TIMING

The search for planetary systems by monitoring the motion of stellar objects along the line-of-sight is, up to now, the most efficient and successful way to detect planets. For millisec-pulsars, the measurements of pulse chronometry is accurate enough to detect orbiting Earth-like planets. For Sun-like stars, with specific instrumentation and fine-tuned reduction techniques, giant planets can be detected. A general description of the io­ dine cell and the simultaneous thorium techniques are given as examples. The interpretation of the observed radial velocity changes as a gravity ef­ fect is not unique. Many other phenomena, intrinsic to stellar atmospheres, may mimic a planetary signature. Stellar activity and stellar pulsations effects are discussed in details in that context. Finally, a summary of the main planetary searches is presented. A prospective is made about expected results for the next millenium.