Mapping out the time-evolution of exoplanet processes

Abstract

There are many competing theories and models describing the formation, migration and evolution of exoplanet systems. As both the precision with which we can characterize exoplanets and their host stars, and the number of systems for which we can make such a characterization increase, we begin to see pathways forward for validating these theories. In this white paper we identify predicted, observable correlations that are accessible in the near future, particularly trends in exoplanet populations, radii, orbits and atmospheres with host star age. By compiling a statistically significant sample of well-characterized exoplanets with precisely measured ages, we should be able to begin identifying the dominant processes governing the time-evolution of exoplanet systems.

A Quick Guide to Nearby Young Associations

“…This is valuable not only to refine our understanding of stellar physics, but also to elucidate open questions about exoplanets and ultimately life in the Universe. For example, studying exoplanets around stars with accurately determined ages has the potential to answer some fundamental questions that are still open about the timescale of exoplanet formation (Chambers 2021), the orbital structures of exoplanets (Christiansen et al 2019;Safsten et al 2020) and how they evolve over time, the erosion of exoplanet atmospheres (David et al 2021), and how mantle degassing rates in rocky exoplanets can affect their atmospheres over time (Unterborn et al 2022). Answering these questions will be crucial to eventually identify systems where life as we know it could plausibly evolve, and to interpret potential biosignatures correctly.…”

Nature vs. nurture: a Bayesian framework for assessing apparent correlations between planetary orbital properties and stellar ages

“…It is debated whether the wide variation in system architecture is primarily due to differences in formation conditions (nature) or due to evolution over time (nurture). Identifying trends between planetary and stellar properties, including stellar age (see, e.g., Christiansen et al 2019), can help distinguish between these competing theories and offer insights as to how planets form and evolve. As our sample of known exoplanets have grown, some apparent correlations between planetary orbital properties and stellar age have started to emerge.…”