Flow of Planets Raises Short Period Fall Off

TL;DR

This paper investigates the distribution of short-period planets, proposing a planetary 'flow' model involving large planets evolving through a 'hot Jupiter' stage, and links stellar metallicity to planetary eccentricity and orbital disruptions.

Contribution

It introduces a planetary flow hypothesis to explain short-period planet distribution and highlights differences in tidal dissipation for different planet sizes.

Findings

Discrepancy in tidal dissipation for giant vs. medium planets.

Correlation between stellar Fe/H and giant planet eccentricity.

Large planets migrating can disrupt smaller planets' orbits.

Abstract

After finding more planets than expected at the shortest period, there has been an effort to explain their numbers by weak tidal friction. However, we find that the strength of tidal dissipation that would produce the occurence distribution found from Kepler planet candidates is different for giant versus medium radii planets. This discrepancy can be resolved if there is a "flow" of the largest planets regularly arriving such that they go through a "hot Jupiter" stage. We also show a correlation of higher stellar Fe/H with higher eccentricity of giant planets that may be from smaller planets having been sent into the star by the migration of the larger planet. This disruption of the orbits of medium and smaller planets could account for the lower occurrence of "hot Neptune" medium radius planets.