Microphysical cloud models for exoplanets

• Antragsteller: Dr. Andras Zsom
• Fachliche Zuordnung: Astrophysik und Astronomie
• Förderung: Förderung von 2012 bis 2014
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 226664855

To date, more than 700 exoplanets have been confirmed and more than 1000 additional candidates have been provided by the Kepler mission. The spectra of some of these exoplanets can be directly observed, which constrain their atmospheric properties. Although the quality and quantity of the data obtained by these observations have improved over time, theoretical models have come to a standstill due to uncertainties related to cloud modeling. I will therefore develop new models of cloud microphysics for two major exoplanet types: hot-Jupiter planets and Earth-sized planets in the Habitable Zone (HZ).Current cloud models for hot-Jupiters simulate nucleation and mixing of vapors, as well as the condensation, vertical sedimentation, and mixing of particles, but do not include particle coagulation. Using time-scale arguments, I show in this proposal that coagulation significantly alters particle size distribution and should not be neglected. I will develop a new Monte Carlo-based cloud model that includes all of the above-described physical processes. This will help to clarify cloud properties on hot-Jupiters and explain spectral observations.Cloud models for Earth-like exoplanets in the HZ are less evolved: even modern models exclusively apply cloud properties measured from Earth. Because cloud properties are expected to differ depending on atmospheric composition, stellar, and orbital properties, these models are only applicable to an exact Earth-analog. I have already developed a new microphysical cloud model for water clouds that consistently reproduces the global energy budget of Earth. I will further include CO2 clouds, the carbon-silicate cycle, and the ice-albedo feedback into the model. This will enable us to constrain the width of the HZ, thus allowing us to estimate the number of potentially habitable planets in our immediate galactic neighborhood.

• DFG-Verfahren: Forschungsstipendien
• Internationaler Bezug: USA
• Gastgeberin: Professorin Dr. Sara Seager