The Influence of Alpha-Element Abundance on Planet Populations and Composition
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Date
2024-05
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The Ohio State University
Abstract
The exact mechanisms of planetary formation remains one of the dominant areas of research in planetary astronomy. Though there are extant prevailing theories (e.g., pebble accretion, core accretion, etc.) for different planets, degeneracies between these theories can make it difficult to resolve how exactly a particular planet formed, or to make predictions on what conditions might be favorable for planet formation. Though the effect of host star metallicity on planet occurrence rates and the correlation between metallicity and planet mass have been well-established, the effect of stellar elemental abundances, particularly that of α-elements, remains comparatively less studied. The goal of this study is to examine planetary compositions, particularly those of rocky planets, through the lens of elemental abundances of their host stars. We determine a functional form [α/Fe]= AeB·[Fe/H]+C + D with fitting parameters A = 0.083, B = -2.025, C = -0.140, and D = -0.046 that describes the value of α-element abundance as a function of metallicity and determine an overall negative correlation between α-element abundance and metallicity for all planet populations except Sub-Saturns due to lack of available metallicity data. Using the planetary interior modeling software ExoPlex, we determine a strong positive correlation between core mass fraction (CMF) and surface gravity, with planetary mass correlating to a combination of these variables.