Project B
Finding planets around young, active stars
Louise Dyregaard Nielsen
How do we separate stellar signals from those induced by exoplanets in the hunt for planets around young stars? A multi-wavelength approach, enabled by new instruments operating in the near-infra-red such as NIRPS and CRIRES+, might be the answer.
With 5000+ confirmed exoplanets, we are starting to appreciate the diversity of planets in our galaxy. They are found to be common - most stars have more than one - and come in a variety of masses, radii, orbital separation, temperatures etc. To fully understand the processes that shape planetary parameters, we need to characterise exoplanets not only of all types but also across all stellar ages.
Stellar activity is a massive obstacle when searching for planets around young stars which are covered in massive star spots while rotating very fast, and often sending out large flares. This 'stellar activity' has a wavelength-dependent component, that is the signal induced by star spots decreases when observing in the near-infrared rather than visible light due to the contrast between the cold spots and hot stellar surface being smaller. Combining near-infrared and visible spectroscopy thus offers the potential to both mitigate and model stellar activity.
In this project, you will learn about stellar activity signals that obstruct the characterisation of young planets with radial velocity measurements. Using data from near-infrared and optical high-resolution spectrographs you will investigate how we can separate stellar 'noise' from bonafide exoplanet signals when observing over a large wavelength range.