THE RELATIONSHIP BETWEEN VERTICAL AND HORIZONTAL MAGNETIC FIELDS IN THE QUIET SUN

Abstract

Vertical magnetic fields have been known to exist in the internetwork region\nfor decades, while the properties of horizontal magnetic fields have recently\nbeen extensively investigated with \\textit{Hinode}. Vertical and horizontal\nmagnetic fields in the internetwork region are considered to be separate\nentities and have thus far not been investigated in a unified way. We discover\nclear positional association between the vertical and horizontal magnetic\nfields in the internetwork region with \\textit{Hinode}. Essentially all of the\nhorizontal magnetic patches are associated with the vertical magnetic patches.\nAlternatively, half of the vertical magnetic patches accommodate the horizontal\nmagnetic patches. These horizontal patches are located around the borders of\nthe vertical patches. The intrinsic magnetic field strength as obtained with\nthe Stokes $V$ line ratio inside the horizontal patches is weak, and is in\nsub-equipartition field regime ($B<700$ G), while the field strength outside\nthe horizontal patches ranges from weak to strong (kG) fields. Vertical\nmagnetic patches are known to be concentrated on mesogranular and supergranular\nboundaries, while the horizontal magnetic patches are found only on the\nmesogranular boundaries. These observations provide us with new information on\nthe origin of the vertical and horizontal internetwork magnetic fields, in a\nunified way. We conjecture that internetwork magnetic fields are provided by\nemergence of small-scale flux tubes with bipolar footpoints, and the vertical\nmagnetic fields of the footpoints are intensified to kG fields due to\nconvective collapse. Resultant strong vertical fields are advected by the\nsupergranular flow, and eventually form the network fields.\n