HAO Colloquium - Johannes Löhner-Böttcher, HAO/Kiepenheuer-Institut für Sonnenphysik

Ultra-Precise Solar Spectroscop

In order to scrutinize and refine existing models of the solar atmosphere, it requires ultra-precise spectroscopic observations of the quiet Sun and active regions. To this end, we have performed state-of-the-art solar observations with the Laser Absolute Reference Spectrograph (LARS) at the Vacuum Tower Telescope (VTT) located at the Teide Observatory on Tenerife. Since LARS combines a high-resolution echelle spectrograph with a laser frequency comb, we obtained solar spectra at an absolute wavelength scale with an unprecedented accuracy of 1m/s (typically required for exoplanet detection via radial velocities). By applying comprehensive steps of data calibration and reference measurements, we were able to translate our absolute measurements into actual Doppler velocities of the solar atmosphere. In this talk, I will present the results of the, so far, most precise and accurate observations of the solar convective blueshift. We will experience how spectral line shifts vary from disk center toward the solar limb, and solve the question if the sunspot umbra is actually at rest.


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Announcement Timing: 
Wednesday, February 13, 2019
Calendar Timing: 
Wednesday, February 13, 2019 - 2:00pm to 3:00pm

Posted by Wendy Hawkins at ext. 1552, whawkins@ucar.edu

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