Recent Advances in Chromospheric and Coronal Polarization Diagnostics

Solar Spectroscopy and (Pseudo-)Diagnostics of the Solar Chromosphere

I first review trends in current solar spectrometry and then concentrate on comparing various spectroscopic diagnostics of the solar chromosphere. Some are actually not at all chromospheric but just photospheric or clapotispheric and do not convey information on chromospheric heating, even though this is often assumed. Balmer Hα is the principal displayer of the closed-field chromosphere, but i...

Remote sensing of chromospheric magnetic fields via the Hanle and Zeeman effects

— The only way to obtain reliable empirical information on the intensity and topology of the weak magnetic fields of the “quiet” solar chromosphere is via the measurement and rigorous physical interpretation of polarization signals in chromospheric spectral lines. The observed Stokes profiles reported here are due to the Hanle and Zeeman effects operating in a weakly magnetized plasma that is i...

Chromospheric evidence for magnetic reconnection

We study the decay phase of an M2.6 flare, observed with ground based instruments at NSO/Sac Peak and with the cluster of instruments onboard Yohkoh. The whole set of chromospheric and coronal data gives a picture consistent with the classical Kopp-Pneumanmodel of two-ribbon flares.We clearly witness new episodes of coronal energy release, most probably due to magnetic reconnection, during the ...

On the Synthesis of Coronal White-Light Polarization Diagnostics

How accurately can we age-date solar-type dwarfs using activity/rotation diagnostics?

It is well established that activity and rotation diminishes during the life of sun-like main sequence (∼F7-K2V) stars. Indeed, the evolution of rotation and activity among these stars appears to be so deterministic that their rotation/activity diagnostics are often utilized as estimators of stellar age. A primary motivation for the recent interest in improving the ages of solar-type field dwar...