Origin and Ubiquity of Short-Period Earth-like Planets: Evidence for the Sequential-Accretion Theory of Planet Formation

The formation of gas giant planets is assumed to be preceded by the emergence of solid cores in the conventional sequential-accretion paradigm. This hypothesis implies that the presence of earth-like planets can be inferred from the detection of gas giants. A similar prediction cannot be made with the gravitational instability (hereafter GI) model which assumes that gas giants (hereafter giants) formed from the collapse of gas fragments analogous to their host stars. We propose an observational test for the determination of the dominant planetformation channel. Based on the sequential-accretion (hereafter SA) model, we identify several potential avenues which may lead to the prolific formation of a population of close-in earth-mass (M⊕) planets (hereafter close-in earths) around stars with 1) short-period or 2) solitary eccentric giants and 3) systems which contain intermediate-period resonant giants. In contrast, these close-in earths are not expected to form in systems where giants originated rapidly through GI. As a specific example, we suggest that the SA processes led to the formation of Corresponding should be addressed to D.L.([email protected])