Seminar: Roadblocks to Detect Earth-like Exoplanets: Solar-type Activity in Radial Velocities
- Date: 21 March 2024, 14:00–15:00
- Location: Ångström Laboratory, 80101 Å and Zoom: https://uu-se.zoom.us/j/65129261212
- Type: Seminar
- Lecturer: Khaled Al Moulla, University of Geneva
- Organiser: Division of Astronomy and Space Physics, Department of Physics and Astronomy
- Contact person: Adam Rains
The radial velocity (RV) technique for detecting exoplanets has in recent years been limited in its applicability to search for Earth-mass planets due to their small semi-amplitudes relative to the intrinsic variability of their host stars. In this talk, I will present the signatures of stellar activity in high-resolution optical and near-infrared (NIR) spectral time series of the Sun and solar-type stars, observed with the HARPS, HARPS-N and NIRPS spectrographs. I will talk about a novel, physically motivated method of RV extraction based on the average formation temperature of spectral segments, in order to demonstrate the differential effect of stellar activity signals as a function of photospheric depth, enabling the separation of temperature-dependent stellar activity from constant Keplerian signals. Additionally, I compare the chromaticity of unsigned magnetic field proxies in the optical versus NIR to evaluate their usefulness as activity indicators with which the stellar signals can be mitigated.
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We shall leave for lunch at around 12:15. There will be fika after the seminar.