Nanna Bach-Møller

My main field of interest is astrobiology, the search for life in space, and I am especially interested in how life might be discovered on distant exoplanets, by looking at so-called biosignatures in the atmospheres of the planets. In my current research, I am focussing less on the astrobiology and more on the atmospheric processes of exoplanets. More specifically I am looking at how the radiative environment of a planet affects the chemistry and cloud formation of its atmosphere. This is done in two ways: 1) I have done experiments with clouds in an atmosphere chamber, to look at how cloud particles behave under gamma radiation. This is important because clouds can have a huge effect on our observations of atmospheres as well as the climate of the planet, and understanding the cloud formation is therefore important to understand the planet. 2) I have done computer simulations of exoplanet atmospheres to model how different types of high-energy radiation affect the chemistry of an atmosphere. This is important because exoplanets are found in many different environments around different host stars and in different parts of the galaxy, which alters the radiation that reaches the planet. We know that radiation can change the atmospheric chemistry, and that these changes can in some cases look like biosignatures. In order to recognize biosignatures, we therefore need to understand the environment of the planets we are looking at.

We have found a correlation between the shape of planetary orbits (eccentricity) and the number of planets (multiplicity) in exoplanet systems, such that larger systems have more circular orbits. This is true for all studied planet types, such as Hot Jupiters (HJ), Cold Jupiters (CJ) and Super Earths (SE).

In my current research I use an atomizer to introduce SiO2 particles into an atmosphere chamber. Similarly to the environment in the upper atmosphere, the particles in the chamber are radiated with UV and gamma radiation, which will affect their tendency to aggregate and form cloud droplets.

Atmosphere models can be used to simulate the chemical and physical processes taking place in an atmosphere, and thereby predict the structure of the atmosphere based on e.g. the chemical composition and type of host star. This is an example of how different molecules are distributed throughout the atmosphere of the exoplanet HATS-6b according to an atmosphere model.

Bach-Møller, Nanna, and Uffe G. Jørgensen. Orbital eccentricity–multiplicity correlation for planetary systems and comparison to the Solar system. Monthly Notices of the Royal Astronomical Society 500.1 (2021): 1313-1322.