The line profiles of Ha in a limb flare on 1998 November 11 appear to be unusually broadened. It is considered that macro-turbulence (or macroscopic mass motions) may be one of the main causes. We use an inversion tec...The line profiles of Ha in a limb flare on 1998 November 11 appear to be unusually broadened. It is considered that macro-turbulence (or macroscopic mass motions) may be one of the main causes. We use an inversion technique to extract the probability distribution of the line-of-sight velocity in the flare. There exist some differences between the velocity distributions deduced from Ha and from Ca II λ8542, which may be because the two lines depend differently on the temperature and velocity. Since the loop density is high, we obtain a rather short cooling time (several tens of seconds) from the hot X-ray loops to the cool loops visible in Ha. Possible origins of the large scale motions are discussed.展开更多
文摘The line profiles of Ha in a limb flare on 1998 November 11 appear to be unusually broadened. It is considered that macro-turbulence (or macroscopic mass motions) may be one of the main causes. We use an inversion technique to extract the probability distribution of the line-of-sight velocity in the flare. There exist some differences between the velocity distributions deduced from Ha and from Ca II λ8542, which may be because the two lines depend differently on the temperature and velocity. Since the loop density is high, we obtain a rather short cooling time (several tens of seconds) from the hot X-ray loops to the cool loops visible in Ha. Possible origins of the large scale motions are discussed.
