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A magnetohydrodynamic simulation of the single-fluid 2-D structure of the solar wind
Xue, Jin-Tao; Wang, Jing-Fang; Qian, Xin +1 more
The system of single-fluid 2-D magnetohydrodynamic (MHD) equations incorporating the momentum term is simulated and the structure of the solar wind in the meridian plane is acquired. The form and location of the momentum addition have an important effect on the velocity and proton density of the solar wind in distant places. By locating the additi…
Fuzzy set theory applied to CME importance classification
Han, Zheng-Zhong; Tang, Yu-Hua
In this paper, fuzzy set theory is applied to a quantitative way of assigning importance class to coronal mass ejection (CME) events based on four observed characteristics, i.e. velocity, span, mass and kinetic energy. The weights to be associated with each of the characteristics and the membership functions of belonging to one of the three import…
An analysis of a solar active region that produced many CMEs
Wang, Min; Xia, Zhi-guo; Zhang, Ba-rong +1 more
In April and May of 1998, six large burst events occurred one after the other in the active region AR8210. We have collected the data of this active region, including its soft X-rays, ultraviolet radiation, radio type-II and -IV bursts as well as its radioheliograph observations. It is found that the process of energy accumulation was rapid and th…
A quantitative research on the classification of coronal mass ejections
Dai, Yu; Zong, Wei-guo; Tang, Yu-hua
It is widely accepted that the properties of coronal mass ejections (CMEs) depend strongly on their structure. Hence it is important, in the study of solar-terrestrial events, to classify CMEs of different morphologies according to intensity. The method of fuzzy comprehensive evaluation can be applied to quantitative research of the CMEs. The memb…
The soft X-ray coronal mass ejection above solar limb of 1998 April 23
Chen, Xiao-juan
Using the observational materials of SXT/HXT aboard satellite Yohkoh and the Nobeyama Radioheliograph (NoRH) on 1998-04-23, a comprehensive study of the soft X-ray coronal mass ejection (CME) above solar SE limb shows that there were two magnetic dipolar sources (MDSs), one magnetic capacity belt (MCB) between the MDSs, one neutral current sheet (…
The proper and space motions of the globular cluster NGC 4147 on the Hipparcos system
Wang, Jia-ji; Wu, Zhen-yu
Dr M. Geffert, of Sternwarte der Universität Bonn, kindly provided us with the positions and proper motions of 82 stars in the field of the globular cluster NGC 4147, reduced with 11 reference stars from the Hipparcos catalogue. We used 54 of these stars to re-reduce the observations by Wang Jia-ji and Gupta [1]. Based on the new proper…
Proper motions of Hipparcos stars in two plate areas
Wang, Shu-he; Tang, Zheng-hong; Jin, Wen-jing
Using the ACT reference catalogue as preliminary reference we have reduced 31 exposures on 15 plates in two areas taken with the 40-cm refractor of our Observatory. Using the central overlapping technique and an iterative procedure we have derived high-precision positions and proper motions for 54 stars, including 16 Hipparcos stars. For the latte…
A kinematic study of the Galaxy
Liu, Yu; Ma, Wen-zhang
Using the proper motion and parallax data for 1011 O-B stars in the Hipparcos Catalogue we have derived the Oort constants, A = 17.60 ± 0.21 (km/s)/kpc, B = -14.62 ± 0.20 (km/s)/kpc, and a solar velocity V⊙ = 16.7 ± 0.10 km/s in the direction l⊙ = 45.3° ± 2.8°, b⊙ = 21.0° ± 2.3°. For a galactocentric distance of th…
Galactic kinematics derived from classical cepheids
Zhu, Zi
On the basis of radial velocity and Hipparcos proper motion data, we have analyzed the galactic kinematics of classical Cepheids. Using the 3-D Ogorodnikov-Milne model we have determined the rotational velocity of the Galaxy to be V0 = 240.5 ± 10.2 km/s, on assuming a glactocentric distance of the Sun of R0 = 8.5 kpc. The res…
The evolutionary status of HD 104237, ɛ Cha and HD 100546
Hu, Jing-yao; Shen, Chuan-jian
Using the new data from Hipparcos and the TD-1 UV data, we fix the positions of three objects, HD 104237, HD 100546 and ɛ Cha in the HR diagram and discuss their theoretical evolutionary status.