A First Comparison of Kepler Planet Candidates in Single and Multiple Systems

TL;DR

This paper analyzes the first four months of Kepler data, revealing that multiple transiting planet systems are common, tend to have smaller planets, and are less likely to contain giant planets, providing insights into planetary system architectures.

Contribution

It provides the first comparative overview of single and multiple transiting planet candidates from Kepler data, highlighting differences in system characteristics and planet sizes.

Findings

Multiple systems account for 17% of Kepler candidates.

Systems with multiple planets are less likely to include giant planets.

Most planets in both singles and multiples are smaller than Neptune.

Abstract

In this letter we present an overview of the rich population of systems with multiple candidate transiting planets found in the first four months of Kepler data. The census of multiples includes 115 targets that show 2 candidate planets, 45 with 3, 8 with 4, and 1 each with 5 and 6, for a total of 170 systems with 408 candidates. When compared to the 827 systems with only one candidate, the multiples account for 17 percent of the total number of systems, and a third of all the planet candidates. We compare the characteristics of candidates found in multiples with those found in singles. False positives due to eclipsing binaries are much less common for the multiples, as expected. Singles and multiples are both dominated by planets smaller than Neptune; 69 +2/-3 percent for singles and 86 +2/-5 percent for multiples. This result, that systems with multiple transiting planets are less likely to include a transiting giant planet, suggests that close-in giant planets tend to disrupt the orbital inclinations of small planets in flat systems, or maybe even to prevent the formation of such systems in the first place.