Speaker
Description
In the field of asteroseismology, solar-like oscillations are mostly observed using either photometry or radial velocity (RV) from high-resolution stellar spectra. A third option is to measure variations in flux in stellar absorption lines in the spectrum that are sensitive to changes in temperature at the surface of the star.
The first detection of solar-like oscillations in any star other than the Sun was based on this principle, where equivalent width changes were measured in just a few stellar absorption lines.
In my master's thesis, I have developed a method that measures changes across the full spectrum in a way that is noise-optimised such that the absorption lines that are most temperature sensitive are weighted highest. Using this method, I have analysed a five-day series of solar spectra taken at the SONG telescope on Tenerife.
The results of this analysis went well above expectations, yielding measurements of temperature variations from spectra with a statistical uncertainty of 0.14 K per 2-second exposure. This allows for strong detections of solar oscillations. With this new tool, we will be able to observe the same physical phenomenon, the solar-like oscillations, from the same data in two different ways: RV and temperature. This will allow us to perform completely new studies of the physics of these oscillations by comparing the two measurements, e.g., in their phase differences or the ratio of oscillation amplitudes.