In 2007 we obtained quiet sun measurements with the Hinode SOT Spectro-Polarimeter, in Ca IIH with the BFI and Magnesium dopplergrams with the NFI. We analyzed the data and published the statistics we found on convective collapse events, a process that intensifies the magnetic field strength up to 1-2 kG (Fischer et al. 2009).
During the data analysis we discovered velocity flows in closely-spaced, opposite-polarity magnetic flux patches. The velocities are larger than the speeds induced by the granulation flows ( see example shown in Fig. 1). In addition, we observed transverse magnetic field patches between the opposite polarities. We propose to study these transient events in detail and determine if there is a magnetic connection between the opposite-polarity magnetic patches. This would indicate a loop configuration in which the observed magnetic patches are the footpoints of a magnetic loop. It is necessary to study the flows at the chromospheric level, which not only gives further evidence of the connection between the footpoints, but can be compared to speeds obtained by theoretical studies of siphon flows in isolated flux tubes by, e.g., Thomas (1988). Simulations indicate it may be difficult to assign a velocity to the simple ”red minus blue” Dopplergram using the Magnesium line images we obtained in the previous observations. Na ID1 appears to be more promising in this regard.
The siphon flow mechanism is a competitor to the previously studied convective collapse, as it also produces strong fields, but has the ”advantage”, that it does not ”drain” the corona of its mass, as a constant mass supply is given by the upflow leg of the loop (Thomas & Montesinos 1990). |
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