Dr. Ryan Terrien, Assistant Professor of Physics & Astronomy, Carleton College
When
Abstract: Abstract: Stellar magnetic activity obfuscates the interpretation of radial velocity (RV) measurements at and below the 1m/s level, masking exoplanetary signals. Spatially resolved solar magnetic field measurements show promise for correcting this effect on sun-like (FGK) stars, but it is unknown whether disk-integrated magnetic field measurements on the sun or other FGK stars will provide the needed level of sensitivity. It is also unknown whether similar measurements could be extended to low-mass (M) stars, which have fundamentally different mechanisms of magnetic activity than FGK stars. I will highlight our new spectroscopic observations that are lending insight into both of these questions. For FGK stars, we have developed a laser heterodyne spectrometer to measure individual solar spectral line profiles at very high resolution (R>10^6), with the aim to empirically determine the disk-integrated spectral fingerprints of magnetic activity. For M stars, we have detected hints of rotationally modulated magnetic signatures in stellar line profiles measured by the highly stabilized Habitable Zone Planet Finder spectrograph, suggesting that magnetic field information may be measurable even in relatively old and quiet M stars. Data from these efforts will help determine the extent to which spectroscopic magnetic field measurements can help improve RV precision across the main sequence.
*Graduate students will meet with the colloquium speaker for lunch Thursday at 12:00 PM (AZ) in conference room N305.