TY - JOUR

T1 - Interpreting the Atmospheric Composition of Exoplanets

T2 - Sensitivity to Planet Formation Assumptions

AU - Molliere, Paul

AU - Molyarova, Tamara

AU - Bitsch, Bertram

AU - Henning, Thomas

AU - Schneider, Aaron

AU - Kreidberg, Laura

AU - Eistrup, Christian

AU - Burn, Remo

AU - Nasedkin, Evert

AU - Semenov, Dmitry

AU - Mordasini, Christoph

AU - Schlecker, Martin

AU - Schwarz, Kamber R.

AU - Lacour, Sylvestre

AU - Nowak, Mathias

AU - Schulik, Matthaus

PY - 2022/7/26

Y1 - 2022/7/26

N2 - Constraining planet formation based on the atmospheric composition of exoplanets is a fundamental goal of the exoplanet community. Existing studies commonly try to constrain atmospheric abundances, or to analyze what abundance patterns a given description of planet formation predicts. However, there is also a pressing need to develop methodologies that investigate how to transform atmospheric compositions into planetary formation inferences. In this study we summarize the complexities and uncertainties of state-of-the-art planet formation models and how they influence planetary atmospheric compositions. We introduce a methodology that explores the effect of different formation model assumptions when interpreting atmospheric compositions. We apply this framework to the directly imaged planet HR 8799e. Based on its atmospheric composition, this planet may have migrated significantly during its formation. We show that including the chemical evolution of the protoplanetary disk leads to a reduced need for migration. Moreover, we find that pebble accretion can reproduce the planet's composition, but some of our tested setups lead to too low atmospheric metallicities, even when considering that evaporating pebbles may enrich the disk gas. We conclude that the definitive inversion from atmospheric abundances to planet formation for a given planet may be challenging, but a qualitative understanding of the effects of different formation models is possible, opening up pathways for new investigations.

AB - Constraining planet formation based on the atmospheric composition of exoplanets is a fundamental goal of the exoplanet community. Existing studies commonly try to constrain atmospheric abundances, or to analyze what abundance patterns a given description of planet formation predicts. However, there is also a pressing need to develop methodologies that investigate how to transform atmospheric compositions into planetary formation inferences. In this study we summarize the complexities and uncertainties of state-of-the-art planet formation models and how they influence planetary atmospheric compositions. We introduce a methodology that explores the effect of different formation model assumptions when interpreting atmospheric compositions. We apply this framework to the directly imaged planet HR 8799e. Based on its atmospheric composition, this planet may have migrated significantly during its formation. We show that including the chemical evolution of the protoplanetary disk leads to a reduced need for migration. Moreover, we find that pebble accretion can reproduce the planet's composition, but some of our tested setups lead to too low atmospheric metallicities, even when considering that evaporating pebbles may enrich the disk gas. We conclude that the definitive inversion from atmospheric abundances to planet formation for a given planet may be challenging, but a qualitative understanding of the effects of different formation models is possible, opening up pathways for new investigations.

KW - IRRADIATED GASEOUS EXOPLANETS

KW - GIANT PLANETS

KW - BROWN DWARFS

KW - TRANSMISSION SPECTRUM

KW - THERMAL INVERSIONS

KW - RETRIEVAL ANALYSIS

KW - ORBITAL MIGRATION

KW - GAS ACCRETION

KW - HR 8799

KW - MASS

U2 - 10.3847/1538-4357/ac6a56

DO - 10.3847/1538-4357/ac6a56

M3 - Journal article

VL - 934

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 74

ER -