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  • Measurement of filament height in Ha and EUV

     


    What:
     
    Measurement of filament height in Ha and EUV
     
     
     
     
    Who:
    Dr. Yan Xu
     
    ( Space Weather Research Lab Center for Solar-Terrestrial Research New Jersey Institute of  Technology)
     
     
    When:
    Monday afternoon, Sep. 7th,3:30 p.m.
     
     
       
    Where:
     
     
     
     
    Room 416, Office Block, 2 West Beijing Road (PMO, CAS)
    Welcome to attend
    ( PMO Academic committee & academic circulating committee)
     
     
       

    abstract


       Observations from two different aspect angles provide the capability to reconstruct the 3D configuration of solar feature. Previous implementations of solar stereoscopy involved observations either from two satellites or from ground-based combined with space observations. For slowly evolving structures, many studies used the solar rotation as good approximations of parallax angles. The STEREO twin spacecrafts, which were launched on 2006 Oct. 25, provide strictly simultaneous observations for the first time. Therefore sterescopy could be carried out for any solar features regardless of their motion and internal variation. I will present the three-dimensional (3D) configuration of filaments observed by STEREO and the Global High Resolution H-alpha network (GHN) in EUV wavelengths and H-alpha line  center, respectively. The 3D coordinates of multiple tracing points on filament were reconstructed by triangulation from two different aspect angles.In EUV observations, the twine STEREO spacecrafts (A and B) observe the Sun with a separation angle at certain time. While a similar angle was produced using the solar rotation of several hours for the ground-based H-alpha observations.

      The frist filament studied was observed on 2007 May 19 above the active region NOAA 10956. Its height information was estimated in both EUV 304 and H-alpha. The result are consistent with previous analysis.The second filament co-existed with a sigmoid structure, which was clearly observed in Soft X-ray and EUV 171 Å by HINODE and STEREO, respectively. This filament partially erupted after a B2 flare occurred in the active region 10944. The stereoscopic 3D reconstruction in EUV 171 shows that the sigmoid structure moved upward from underneath to above the filament. This motion results a relative position change between the filament and the sigmoid, which has never been observed before. It happened right before the partial filament eruption, making itself a possible precursor of the eruption.

      

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