Seminar: Spectra and limb darkening of magnetized stars
- Date: 19 September 2024, 14:00–15:00
- Location: Ångström Laboratory, 90102 and Zoom: https://uu-se.zoom.us/j/63294871517.
- Type: Seminar
- Lecturer: Nadiia Kostogryz, Max-Planck-Institut für Sonnensystemforschung
- Organiser: Division of Astronomy and Space Physics, Department of Physics and Astronomy
- Contact person: Adam Rains
Magnetic fields form within stars and emerge on their surfaces forming magnetic features such as spots, faculae, and magnetic networks. 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.
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We shall leave for lunch at around 12:15. There will be fika after the seminar.