Nadiia Kostogryz (MPS): Spectra and limb darkening of magnetized stars

Thursday 19 Sept 2024, 14:00 → 15:00 Europe/Stockholm

Title: Spectra and limb darkening of magnetized stars
Speaker: Nadiia Kostogryz
Affiliation: Max-Planck-Institut für Sonnensystemforschung
Time: Thursday 19th September 2024, 14:00 to 15:00
Location:  90102 Å

Abstract: Magnetic fields form within stars and emerge on their surfaces forming magnetic features such as spots, faculae, and magnetic network They affect properties of stellar atmospheres and therefore emergent radiation. In particular, magnetic features cause radial velocity jitter which interferes with detection and characterization of exoplanets. They also contaminate exoplanetary transmission spectra preventing us from accurate characterization of exoplanetary atmosphere.
Here, we model the effect of magnetic features on low- and high- resolution stellar spectra using 3D radiative magnetohydrodynamics (MHD) code MURaM and radiative transfer code MPS-ATLAS.
We demonstrate that faculae and magnetic network modify stellar limb darkening needed for accurate determination of planetary radii and atmospheric composition. We demonstrate that including magnetic fields in our simulations allows solving the limb darkening conundrum: a steeper drop in stellar brightness towards the limb in simulations than in observations. We show that properties of the magnetic features and their spectra strongly depend on stellar fundamental parameters.