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Planet Evaporation as a Window into Exoplanetary Origins

Project description

Study on planetary atmosphere evaporation sheds light on planet formation

Notwithstanding research progress, an understanding of processes leading to planet formation remains limited. Many exoplanets, that is, planets orbiting around stars other than the Sun, have volatile atmospheres. Close proximity to stars makes exoplanets’ upper atmospheres vulnerable to mass-loss through evaporation caused by heating. PEVAP project partners have recently played a pivotal role in establishing that evaporation of planetary atmospheres drives the evolution of the observed exoplanet population. This research development renders evaporation understanding crucial to deciphering exoplanet formation. The EU-funded PEVAP project goal is to create the world’s first comprehensive models of exoplanet evaporation. Providing answers to key questions around evaporation processes and effects, the PEVAP project team will help explain how exoplanets are born.


Modern astronomy has truly entered the exoplanet era. Although our knowledge of what planet formation produces has grown immensely thanks to observational advances, our actual understanding of the physical processes that give rise to planets and planetary systems is limited. We now know most stars are unlike our own Sun, in that they host planets which orbit around their star with periods of months or shorter, yet many have volatile rich atmospheres. These planets must result from a dominant (if not the dominant) mode of planet formation, yet they were completely missing from our planet formation theories a decade ago.
Planets which are close to their parent star are extremely vulnerable to mass-loss through evaporation, where UV/X-ray photons can heat their upper atmospheres to close to the escape temperature, causing them to lose-mass. Recently, I have played a leading role in showing that evaporation drives the evolution of the observed exoplanet population. Thus, the observed exoplanet population is not representative of the one at birth; to use it as a probe of planet formation we must understand evaporation. However, the evaporation of highly-irradiated planetary atmospheres is not well understood. This especially true for terrestrial planets where the atmospheres are dominated by heavy elements.
My team will use a combination of theory, simulations and observations to build the first global and comprehensive models of exoplanet evaporation. In doing this, my team will use evaporation as a window into planet formation by answering the following key questions:
1 What are the mass-loss rates and evaporative flow structures for the full spectrum of observed planets?
2 How can we use observations of evaporating planets to learn about their compositions and histories?
3 How does evaporation affect and control the evolution of planets and their atmospheres?
By understanding how exoplanets evaporate and evolve, my team will unveil the exoplanet population at birth.

Host institution

Net EU contribution
€ 1 464 320,00
United Kingdom

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London Inner London — West Westminster
Activity type
Higher or Secondary Education Establishments
Total cost
€ 1 464 320,00

Beneficiaries (1)