Vortragsreihe: Exoplaneten – Planeten ferner Sterne

Lecture by Prof. Dr. Lena Noack (FU Berlin): How the interior of a planet influences its habitability

Exoplanets (planets orbiting other stars) are now on everyone's lips - at least since half of the Nobel Prize in Physics was awarded to two exoplanet discoverers in 2019 - Michel Mayor and Didier Queloz, who found the first exoplanet around a sun-like star in Switzerland over 20 years ago. The first exoplanets were hot gas giants (not unlike our planet Jupiter) orbiting very close to their star. For a little over ten years, however, more and more rocky planets have been discovered - planets that are not so dissimilar to our Earth or our neighboring planets Mars and Venus.

We have discovered over 5000 exoplanets so far, even if this represents only a fraction of all the planets that actually exist in the Milky Way alone. The data available for each individual exoplanet remains very limited, however, and we have to rely on model calculations and all available observational data to find out more about these mysterious places. For many planets, the mass and radius (and thus the average density) of the planets could be determined. Measurements of a planet's spectrum as it orbits in front of the star can provide initial estimates of its atmosphere. The composition and activity of the star itself can also provide us with initial ideas about which minerals and metals could have been accumulated in the building blocks of the planets and in what frequency, and how long ago the planets were formed. Detailed computer simulations can then estimate the composition of the later planets and the possible processes in the interior and on the surface of these planets. This helps us to understand whether an exoplanet should resemble a rather hellish planet like our neighboring planet Venus, or whether an atmosphere can form that would allow liquid water on the surface (and thus perhaps also life).

The combination of different computer simulations allows exoplanet researchers to better understand the diversity and evolution of the thousands of exoplanets that have already been discovered, and perhaps ultimately find the needle in the haystack - a second Earth.