Astrometric signatures of giant-planet formation

摘要: The discovery1,2,3,4,5,6 of giant planets orbiting nearby solar-type stars raises anew the question how they formed. Two very different mechanisms have been proposed. Gravitational instability7,8 is process by which form directly from gas in accrection disk around young star. other alternative core accretion9,10, where rocky cores about 10 Earth masses form, followed hydrodynamical accretion gas. Here I show that these processes astrometric signatures, and it observationally possible to distinguish between them. Planets through gravitational instabilities do so rapidly, within just a few hundred years onset instability nascent planet making stellar object wobble its orbit. This can be seen youngest objects, with ages as little 0.1 Myr. If accretion, an observable will not visible for 10–20 Myr. Observations suitable ensemble optically objects (such those Taurus molecular cloud) over period several decades should able determine two responsible giant-planet formation.