# Unexpected gap creating two peaks in the periods of planets of metal-rich sunlike single stars

## TL;DR

This study reveals a bimodal distribution with two peaks and a gap in the orbital periods of large, metal-rich, sun-like stars' planets, challenging previous assumptions about planet formation uniformity.

## Contribution

It uncovers a previously unrecognized bimodal period distribution with a significant gap, supported by statistical tests, indicating more complex planet formation processes.

## Key findings

- Two strong peaks in planet periods separated by a gap.
- The bimodal feature is unlikely due to observational biases.
- Features are most prominent in single-planet systems.

## Abstract

The pileup of planets at periods of roughly one year and beyond is actually a bimodal peak with a wide, sharp gap splitting the peak of the pileup in a major population of large planets. Consisting of nearly 40\% of planets with periods past 200 days, the periods of the planets of metal-rich stars like the sun in surface gravity which do not have a stellar companion show two strong peaks separated by a sparsely populated region. Monte Carlo tests show that this structure is unlikely to occur in random distributions, and a comparison with objects from all the other populations show that this feature is unlikely to be due to observational effects. The peaks have their highest density next to the gap. These two peaks are most strongly seen in single-planet systems, though the gap persists in multiple planet systems. These features are likely characteristic of planets with masses not too much lower than Jupiter, and perhaps not too much higher. The presence of well-defined features in the period distribution show that planet formation may be much more uniform than previously expected.