Magnetic field oscillations all over the quiet Sun María Jesús Martínez González Instituto de Astrofísica de Canarias

Analysing IMaX data… Å Fe I line g=3, G=9 (very sensitive to circular and linear polarisation) resonant line (extremely sensitive to temperature) I,Q,U,V observed at  =  40,  80, 2?? mÅ polarimetric sensitivity ~10 -3 I c ???? area observed with a cadence of ~32 sec …at first sight, it seems that, quiet Sun circular polarisation signals change their shapes and their area according to granular motions.

Magnetic signals in the intergranular lanes change their shapes and their area according to the “free space” they have at the intergranules. We performe an inversion in the “weak field” approximation: C=4.6686· λ 2 g eff Contours at constant magnetic flux

Time evolution of the area of low flux patches

(after filtering the p-modes) time evolution of other physical quantities

Three magnetic patches surrounding a common granule (d~1600 km) oscillating in fase.

Time evolution of the area of strong flux patches

Summarising... The area (hence the magnetic field) of the magnetic patches at the quiet Sun oscillate. The oscillations have some periods compatible with the p-modes and larger periods (up to 11 min). The oscillations have abrupt changes of the period in the course of the time series. The oscillations have a variety of behaviours (damped, amplified, and sinuisoidal). Sometimes we see different patches surrounding a common granule oscillating in phase.

Hence, we suggest that… either the characteristic modes of the structure vary due to changes in their physical properties (density, magnetic field orientation, sub- resolution structure,etc.), or that they are not characteristic modes of oscillation at all. But more importantly, the variations in the area we detect are so strong that, possibly, a non-linear analysis of the variations is required, hence, the classical models are not suitable to explain these observations. If not being flux tube oscillation modes, the pattern we observe might be the forcing due to the evolution of the granules. (the field lines are continuously squashed or released everywhere and hence the magnetic fields are constantly being amplified or weakened )

And in the upper photosphere (Mg b I line)...