Mercury transit on November 11th

On Nov 11, 2019 KIS scientists together with C. Schmidt from Boston University observed and recorded the Mercury transit in front of the Sun with the GREGOR and Chrotel telescopes. Mercury transits are rare events and the next one will occur only in 2032. Such transits are great opportunities to study Mercury's exosphere. The first two-dimensional image of this exosphere was obtained by H. Schleicher at KIS at the occasion of the second to last transit in 2003, using the VTT telescope and the spectral line of sodium.

The picture shows the full Sun taken by Chrotel in the H-alpha line at 656 nm a few minutes after the transit started with Mercury visible just at the Eastern (left) limb. The H-alpha wavelength shows the chromosphere, a higher part of the solar atmosphere than what is seen by naked eye. The inset shows an H-alpha image from GREGOR. Mercury is partially in front of solar spicules, which are plasma jets that reach up to 10000 km above the solar limb. The horizontal line shows the spectrograph slit of the GRIS instrument, which recorded spectra of Helium and Silicon.

Our observations focused on detecting Sodium and potentially Helium and Silicon in its very thin atmosphere. The transit also allows us to study what to expect when we attempt to measure atmospheres of exoplanets during their transits in front of stars. We obtained more than 10 TB of data, which will be analyzed in the coming months.

The picture shows the full Sun taken by Chrotel in the H-alpha line at 656 nm a few minutes after the transit started with Mercury visible just at the Eastern (left) limb. The H-alpha wavelength shows the chromosphere, a higher part of the solar atmosphere than what is seen by naked eye. The inset shows an H-alpha image from GREGOR. Mercury is partially in front of solar spicules, which are plasma jets that reach up to 10000 km above the solar limb. The horizontal line shows the spectrograph slit of the GRIS instrument, which recorded spectra of Helium and Silicon.