CAN THE PERTURBATION OF A STELLAR MOTION IN A TRIPLE SYSTEM MIMIC A PLANET?

摘要

The first extra-solar planets have been detected by the measurement of the wobble of the parent star. This wobble leads to the periodic modulation of three observables: radial velocity, position on the sky and time of arrival of periodic signals. I show that the same wobble, and therefore the same modulation of the three observables, can be due to the presence of a distant binary stellar companion. Thus, the observation of the wobble does not, by itself, constitute a proof of a planet detection; in particular, as-trometric confirmation of a wobble does not necessarily provide a sufficient proof of the existence of a planet candidate detected by radial velocity; additional conditions must be fulfilled. I investigate the observed wobble for the planet candidates detected up to now by radial velocity and find that, for each case, a wobble due to a binary stellar companion can be excluded.