Relation between Trees of Fragmenting Granules (TFG) and supergranulation evolution from Hinode observation

Th. Roudier, J.M. Malherbe, M. Rieutord, Z. Frank

Hinode is a Japanese mission developed and launched by ISAS/JAXA, with NAOJ as domestic partner and NASA and STFC (UK) as international partners. It is operated by these agencies in co-operation with ESA and NSC (Norway).

HINODE 24 H sequence, 29-30 AUGUST 2007, SOT BFI (Blue continuum and Gband), SOT NFI (STOKES IV FeI 6302), pixel size 0.11 arc sec, time step 50.2 s, disk centre

ABSTRACT
Aims: we investigate the structure and evolution of interior cells of solar supergranulation. From Hinode observations, we explore the motions on solar surface at high spatial and temporal resolution. We derive the main organization of the flows inside supergranules and their effect on the magnetic elements.
Methods: to probe the superganule interior cell, we used the TFG evolution and their relations to horizontal flows.
Results: evolution of TFG and their mutual interactions result in cumulative effects able to build horizontal coherent flows with longer lifetime than granulation (1 to 2 hours) over a scale up to 12". These flows clearly act on the diffusion of the intranetwork magnetic elements and also on the location and shape of the network.
Conclusions: from our analysis during 24 hours, TFG appear as one of the major elements of the supergranules which diffuse and advect the magnetic field on the Sun’s surface. The strongest supergranules contribute the most to magnetic flux diffusion in the solar photosphere.

On line supplement material: movies (Mpeg 4 format)

The FOV (60" x 62") is centered on the well formed superganule with a quasi closed magnetic network at the boundaries. The time step is 50 s between each frame and the duration is 24 hours (1716 frames). The pixel size is 0.16".

Movie 1 : Evolution of the magnetic field.

Movie 2 : Evolution of the TFG with various colors; the longitudinal magnetic field is superimposed (yellow and white).

Movie 3 : Evolution of corks (indicated by crosses) relatively to the TFG (various colors); the longitudinal magnetic field is superimposed (yellow and blue).

Movie 4 : Evolution of corks (indicated by crosses) relatively to the intranework (IN) and network (NE) longitudinal magnetic field (yellow and blue).

Movie 5 : Evolution of horizontal velocity magnitudes (Vh mag, grey levels) and the longitudinal magnetic field (red and blue).

Movie 6 : Evolution of horizontal velocity magnitudes Vh mag, divergence of horizontal velocities (positive for divergent in red, negative for convergent in blue) together with magnetic fields (yellow and white contours).

Movie 7 : Evolution of the positive divergence (in red) relatively to the families (TFG in various colors) and magnetic fields (yellow and blue).

Movie 8 : Evolution of the positive divergence (in blue) relatively to the families (TFG in various colors), magnetic field magnitude (white contours) and horizontal velocity magnitudes Vh mag (grey levels).

Movie 9 : Evolution of the families (TFG in various colors), horizontal velocity magnitudes Vh mag (white) and magnetic fields (yellow and blue contours).

Movie 10 : Evolution of the families (TFG in various colors) and horizontal velocity magnitudes Vh mag (white).