Abstract
Abstract We study the photospheric evolution of an exploding granule observed in the quiet Sun at high spatial (∼0.″3) and temporal (31.5 s) resolution by the imaging magnetograph Sunrise/IMaX in 2009 June. These observations show that the exploding granule is cospatial to a magnetic flux emergence event occurring at mesogranular scale (up to ∼12 Mm2 area). Using a modified version of the SIR code for inverting the IMaX spectropolarimetric measurements, we obtain information about the magnetic configuration of this photospheric feature. In particular, we find evidence of highly inclined emerging fields in the structure, carrying a magnetic flux content up to ∼4 × 1018 Mx. The balance between gas and magnetic pressure in the region of flux emergence, compared with a very quiet region of the Sun, indicates that the additional pressure carried by the emerging flux increases the total pressure by about 5% and appears to allow the granulation to be modified, as predicted by numerical simulations. The overall characteristics suggest that a multipolar structure emerges into the photosphere, resembling an almost horizontal flux sheet. This seems to be associated with exploding granules. Finally, we discuss the origin of such flux emergence events.
Highlights
A typical phenomenon observed in the quiet-Sun granulation pattern is the appearance of exploding granules (EGs)
In order to compare the thermal and pressure stratification in the EG containing the emerging flux region with those found in the undisturbed photosphere, we have studied the thermodynamical properties in FoVEG and FoVQS
Imaging Magnetograph eXperiment (IMaX)/Sunrise observations of the solar photosphere taken at disk center have revealed a number of small-scale episodes of magnetic flux emergence
Summary
A typical phenomenon observed in the quiet-Sun granulation pattern is the appearance of exploding granules (EGs) These are individual bright granules that expand more than normal granular cells, and fragment into several smaller granules. They have a rather long lifetime, with an average value of ≈9 minutes, and reach a maximum diameter of about 4′′–5′′ (Mehltretter 1978; Title et al 1989; Rast 1995).
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