Interstellar polarization at high galactic latitudes from distant stars III. Distribution of the polarization vectors - evidence for distinct zones

We make a map of interstellar polarization direction around the North Galac tic Pole and study the distribution of the revealed magnetic field lines. W e study in detail Markkanen's (1979) cloud and other local features apparen t in the polarization map, and compare them with the IRAS 100 micron map. T he elongated Markkanen's cloud (at a distance of 100-200 pc) and its magnet ic field lines coincide with IRAS filaments. The cloud throws a shadow in s oft (0.25 keV ROSAT) X-rays, as expected from its close distance. Another i nteresting feature is the polarization alignment around l approximate to 19 0 degrees, b approximate to 75 degrees - 83 degrees, with the direction abo ut perpendicular to that of Markkanen's cloud, hence also perpendicular to the Local Spiral spur. This feature is shown only by stars more distant tha n 300 pc, and in the IRAS map it is located in a region of enhanced brightn ess. The differing polarization directions partially overlap in the sky, su ggesting the existence of two kinds of clouds with different magnetic field directions. The IRAS 100 micron map is faint towards the sector 40 degrees < I < 135 de grees. Only in this region with little nearby diffuse matter is there some signature of the global magnetic field (parallel with l = 78 degrees).