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Media type:
E-Article
Title:
No Metallicity Correlation Associated with the Kepler Dichotomy
Contributor:
Munoz Romero, Carlos E.;
Kempton, Eliza M.-R.
imprint:
American Astronomical Society, 2018
Published in:The Astronomical Journal
Language:
Not determined
DOI:
10.3847/1538-3881/aaab5e
ISSN:
0004-6256;
1538-3881
Origination:
Footnote:
Description:
<jats:title>Abstract</jats:title>
<jats:p>NASA’s <jats:italic>Kepler</jats:italic> mission has discovered thousands of planetary systems, ∼20% of which are found to host multiple transiting planets. This relative paucity (compared to the high fraction of single transiting systems) is postulated to result from a distinction in the architecture between multi-transiting systems and those hosting a single transiting planet: a phenomenon usually referred to as the <jats:italic>Kepler</jats:italic> dichotomy. In this paper, we investigate the hypothesis that external giant planets are the main cause behind the over-abundance of single- relative to multi-transiting systems, which would be signaled by higher metallicities in the former sample. To this end, we perform a statistical analysis on the stellar metallicity distribution with respect to planet multiplicity in the <jats:italic>Kepler</jats:italic> data. We perform our analysis on a variety of samples taken from a population of 1166 <jats:italic>Kepler</jats:italic> main-sequence planetary hosts, using precisely determined metallicities from the California-<jats:italic>Kepler</jats:italic> survey and Swift et al. Contrary to some predictions, we do not find a significant difference between the stellar metallicities of the single- and multiple-transiting planet systems. However, we do find a 55% upper bound for systems with a single non-giant planet that could also host a hidden giant planet, based on metallicity considerations. While the presence of external giant planets might be one factor behind the <jats:italic>Kepler</jats:italic> dichotomy, our results also favor alternative explanations. We suggest that additional radial velocity and direct imaging measurements are necessary to constrain the presence of gas giants in systems with a single transiting planet.</jats:p>