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The Observations And Analyses Of Solar Active Regions

Posted on:2017-05-23Degree:MasterType:Thesis
Country:ChinaCandidate:H B LiFull Text:PDF
GTID:2310330503996481Subject:Astrophysics
Abstract/Summary:PDF Full Text Request
As the closest star, the sun not only provides us endless light and heat,but also enduringly influences our daily life. Since that, the solar physic is a significant branch of astronomy. Solar active regions are generally considered as some specific regions on the surface of the sun that are often observed with strong magnetic structure and with many active phenomena, which are believed to have great influences on our space whether. With the rapid development of the technology of telescopes, there are more and more solar telescopes coming into service which provide us plenty of data products of those solar activity in active regions, which are very useful for us to understand the essence of solar active regions.Many solar activity phenomena, such as sunspot, flare, filament eruption,coronal mass ejection and so on, have a close relation with the stronger magnetic field in solar active regions. On the other hand, the magnetic pressure and tension provided by those magnetic field can support the denser plasmas in a prominence against gravity. Besides that, the magnetic field can also provides an adiabatic environment in solar atmosphere, and so allows cool plasmas to exist in a hotter environment, as in filaments or coronal loops. What's more, the energy stored in the magnetic field are also rich enough to drive a violent eruption, such a solar flare or a filament eruption. But as result in the complexity of solar active region and the restriction of observation's precision, the detailed performance and thenature of solar active regions have not been well understood.Based on plenty of data with high spatial and temporal resolution, we study a group of typical active phenomenons of solar active regions. First of all, we have a detailed study about the spatial distribution of the magnetic index n for four different filament eruptive events. Their distribution of n shows that both split legs of this type of active filament are near an abnormal region of n( hereafter ABN region). This ABN region consists of two subregions that with larger n and smaller n with value change abruptly, respectively. An analysis of the magnetic topological configuration of this ABN region has also be done, and the result indicates those ABN regions correspond to a kind of special QSLs across which the connectivity of magnetic field is discontinuous.Beyond that, we also study a new coronal loop oscillation event, which was observed by the AIA on board the SDO at 2015 June 08. The observation indicates that obvious difference oscillation existing in both near loops and same loops. For the near loops, we find they oscillated with obviously different periods and amplitudes after the impulse of a C7.2 GOSE-class flare. We have a detailed analysis about this phenomenon and suggest that it is a difference of the loop's internal magnetic field may be necessary for this phenomenon. As for the same loop, we find that the loop underwent a decay phase in the part away from the triggering flare, while the other part have a growing phase when oscillating. A possible reason is provided by us for this abnormal performance of oscillation.We also show a simple numerical model to testify our assume and get some supportive result.At last, We test a phase congruency method for automatically extracting coronal loops from the coronal observation data and propose a new coronal loop detective technology based this method. On account of smooth changes of the direction along coronal loops, the possible direction of loops is restricted in a small range for improving the detective result. Moreover, inspired by coronal loops' s structural characteristics, we firstly suggest that both the change of result directions and the flux of result points can be used to terminate the loop detection. Finally, several coronal images are detected by our loop extracting method, and the result indicates that the congruency enhanced image is exactly suitable for coronal detection and extraction and our new loop detective method also can extract most of loops in the test images completely and accurately.
Keywords/Search Tags:solar active region, filament eruption, magnetic decay index, loop oscillation, loop auto-detection
PDF Full Text Request
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