Identification of the sources of the high-speed and...

1. Introduction

[2] The problem of the formation and acceleration of the solar wind is one of the most important and most interesting problems of the solar physics. The solar wind is a supersonic flow of plasma streams. There are high-speed (above 550 km s^-1 ) and low-speed streams of the solar wind. The high-speed streams are characterized by high temperature and low density, whereas low-speed streams have lower temperature and higher density. There is also a difference in the substance composition. The dynamics of the solar wind parameters (speed, density, temperature, and the magnetic field strength) are not a clear and unambiguous response to the processes in the solar atmosphere. The high-speed streams are one of the main causes of the whole set of geomagnetic phenomena. The regions of open configurations of the magnetic fields related to coronal holes are believed to be a source of formation of these streams. High-speed and low-speed streams of the solar wind differ not only by the speed, density of the plasma, and its composition, but by the character of variability as well. Low-speed streams are characterized by more sharp and frequent oscillations of the parameter values, whereas high-speed streams are more homogeneous. Their sources are evidently different. For example, Lotova et al. [2002] concluded that the difference in the solar wind speed is determined by the structure of the coronal magnetic field. High-speed streams are generated in the regions with the open configuration of field lines, whereas low-speed streams are formed over magnetic structures of the closed type typical for the main body of a streamer. The streams with the lowest speeds are not related to coronal structures of the streamer type. They are generated in the coronal regions with the magnetic fields of a mixed type. The solar rotation leads to an interaction of these streams and formation of a complicated interacting structure rotating together with the Sun.

[3] Some authors consider the active regions to be the source of high-speed solar wind streams. Mustel [1980] supposed that active regions are the sources of quasi-stationary corpuscular streams. Active regions on the solar disk are preceded in certain cases by coronal holes with a relatively undisturbed area between them. This explains the origin of the idea of the so-called "cone of avoidance" [Mustel, 1980]. According to Kuklin and Plyusnina [1979] the sources of high-speed solar wind streams are located in the vicinity of the complexes of activity.

[4] According to the current data of optical and radio observations the solar corona has a fine structure at all observed scales. All the structural features of the corona and their changes within the solar cycle are manifested in variations in solar wind parameters. Analyzing the observations in the radio range made by the National Radio Astronomy Observatory's Very Large Array, Woo [1996] showed that fine structure followed down to the photosphere is observed in the regions of location of coronal holes. Since the coronal hole regions are sources of high-speed geoefficient solar wind streams, to explain the mechanism of formation and acceleration of the solar wind, one needs an exact picture of the processes occurring in all layers of the solar atmosphere. The SOHO data [Insley et al., 1995] show that there are active processes at the boundaries of the chromospheric net in the zones of coronal holes location. McKenzie et al. [1995] were the first to assume that high-speed streams of the solar wind are generated directly in the chromospheric network in the vicinity of the basis of coronal holes and that possibly high-frequency waves are generated in the process of a small-scale reconnection. Bocchialini and Vial [1996] detected differences in the structure of the high-chromosphere and low-transition-region network between the regions of equatorial coronal hole location and quiet regions.

[5] The main goal of this work is to compare coronal holes in X ray and He I line. Compare their mutual location, photospheric magnetic fields peculiarities in arias corresponding to the coronal holes locations, and corresponding solar wind response and try to understand why similar X-ray coronal holes produce different solar wind evolution.