| Abstract from DBPedia | The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. Superposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface. At a distance of more than a few solar radii from the Sun, the solar wind reaches speeds of 250–750 km/s and is supersonic, meaning it moves faster than the speed of the fast magnetosonic wave. The flow of the solar wind is no longer supersonic at the termination shock. Other related phenomena include the aurora (northern and southern lights), the plasma tails of comets that always point away from the Sun, and geomagnetic storms that can change the direction of magnetic field lines.太陽風（たいようふう、英: solar wind）は、太陽から吹き出す極めて高温で電離した粒子（プラズマ）のことである。これと同様の現象はほとんどの恒星に見られ、「恒星風」と呼ばれる。なお、太陽風の荷電粒子が存在する領域は太陽圏と呼ばれ、それと恒星間領域の境界はヘリオポーズと呼ばれる。 大規模な太陽フレアが発生した際に太陽風が爆発的に放出され、地球上や人工衛星などに甚大な被害を及ぼす現象は、太陽嵐 (solar storm) とも呼ばれる。 (Source: http://dbpedia.org/resource/Solar_wind) |
