# A Flat Inner Disk Model as an Alternative to the Kepler Dichotomy in the Q1 to Q16 Planet Population

## TL;DR

This study demonstrates that assuming flat inner planetary disks can explain the observed distribution of transiting planets around Kepler stars without requiring a dichotomous planet formation ability, challenging previous models.

## Contribution

It introduces a flat inner disk model that reproduces Kepler planet multiplicity data without the Kepler dichotomy assumption.

## Key findings

- Flat disk model matches observed planet multiplicity.
- Average of about 2 planets per star in the specified period and radius range.
- Contrasts with Solar System planet distribution.

## Abstract

We use simulated planetary systems to model the planet multiplicity of Kepler stars. Previous studies have underproduced single planet systems and invoked the so called Kepler dichotomy, where the planet forming ability of a Kepler star is dichotomous, producing either few or many transiting planets. In this paper we show that the Kepler dichotomy is only required when the inner part of planetary disks are just assumed to be flared. When the inner part of planetary disks are flat, we reproduce the observed planet multiplicity of Kepler stars without the need to invoke a dichotomy. We find that independent of the disk model assumed, the mean number of planets per star is approximately 2 for orbital periods between 3 and 200 days, and for planetary radii between 1 and 5 Earth radii. This contrasts with the Solar System where no planets occupy the same parameter space.