Cirtain J W, Golub L, Lundquist L, van Ballegooijen A, Savcheva A, Shimojo M, Deluca E, Tsuneta S, Sakao T, Reeves K, Weber M, Kano R, Narukage N, Shibasaki K
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
Science. 2007 Dec 7;318(5856):1580-2. doi: 10.1126/science.1147050.
Coronal magnetic fields are dynamic, and field lines may misalign, reassemble, and release energy by means of magnetic reconnection. Giant releases may generate solar flares and coronal mass ejections and, on a smaller scale, produce x-ray jets. Hinode observations of polar coronal holes reveal that x-ray jets have two distinct velocities: one near the Alfvén speed ( approximately 800 kilometers per second) and another near the sound speed (200 kilometers per second). Many more jets were seen than have been reported previously; we detected an average of 10 events per hour up to these speeds, whereas previous observations documented only a handful per day with lower average speeds of 200 kilometers per second. The x-ray jets are about 2 x 10(3) to 2 x 10(4) kilometers wide and 1 x 10(5) kilometers long and last from 100 to 2500 seconds. The large number of events, coupled with the high velocities of the apparent outflows, indicates that the jets may contribute to the high-speed solar wind.
日冕磁场是动态的，磁力线可能会重新排列、重新组合，并通过磁重联释放能量。巨大的能量释放可能会产生太阳耀斑和日冕物质抛射，在较小尺度上则会产生X射线喷流。“日之出”卫星对极区日冕洞的观测显示，X射线喷流有两种不同的速度：一种接近阿尔文速度（约每秒800公里），另一种接近声速（每秒200公里）。观测到的喷流比以前报道的要多得多；我们在这些速度下平均每小时检测到10次事件，而以前的观测每天仅记录到少数几次，平均速度较低，为每秒200公里。X射线喷流宽约2×10³至2×10⁴公里，长1×10⁵公里，持续时间为100至2500秒。大量的事件，再加上明显外流的高速度，表明这些喷流可能对高速太阳风有贡献。
