Description du projet
Une étude sur l'érosion atmosphérique des planètes nous éclaire sur leur formation
Malgré les progrès de la recherche, notre compréhension des processus conduisant à la formation des planètes reste limitée. De nombreuses exoplanètes, c’est-à-dire des planètes gravitant autour d’autres étoiles que le Soleil, possèdent une atmosphère volatile. La proximité des étoiles rend la haute atmosphère des exoplanètes vulnérable aux pertes de masse par évaporation thermique. Les partenaires du projet PEVAP ont récemment joué un rôle essentiel en établissant que l’érosion des atmosphères planétaires influençait l’évolution de la population d’exoplanètes observées. Ce résultat de recherche rend la compréhension de ce phénomène d’évaporation cruciale pour décrypter l’histoire de la formation des exoplanètes. Le projet PEVAP, financé par l’UE, a pour objectif de créer les premiers modèles complets d’érosion atmosphérique exoplanétaire au monde. En apportant des réponses aux questions clés sur les processus et les effets de l’érosion, l’équipe du projet PEVAP contribuera à expliquer comment naissent les exoplanètes.
Objectif
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.
Champ scientifique
Mots‑clés
Programme(s)
Thème(s)
Régime de financement
ERC-STG - Starting GrantInstitution d’accueil
SW7 2AZ LONDON
Royaume-Uni