Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Multi-instrument observations of coronal loops(Montana State University - Bozeman, College of Letters & Science, 2012) Scott, Jason Terrence; Chairperson, Graduate Committee: Petrus MartensThis document exhibits results of analysis from data collected with multiple EUV satellites (SOHO, TRACE, STEREO, Hinode, and SDO). The focus is the detailed observation of coronal loops using multiple instruments, i.e. filter imagers and spectrometers. Techniques for comparing the different instruments and deriving loop parameters are demonstrated. Attention is given to the effects the different instruments may introduce into the data and their interpretation. The assembled loop parameters are compared to basic energy balance equations and scaling laws. Discussion of the blue-shifted, asymmetric, and line broadened spectral line profiles near the footpoints of coronal loops is made. The first quantitative analysis of the anti-correlation between intensity and spectral line broadening for isolated regions along loops and their footpoints is presented. A magnetic model of an active region shows where the separatrices meet the photospheric boundary. At the boundary, the spectral data reveal concentrated regions of increased blue-shifted outflows, blue wing asymmetry, and line broadening. This is found just outside the footpoints of bright loops. The intensity and line broadening in this region are anti-correlated. A comparison of the similarities in the spectroscopic structure near the footpoints of the arcade loops and more isolated loops suggests the notion of consistent structuring for the bright loops forming an apparent edge of an active region core.Item Snapshot imaging spectroscopy of the solar transition region: the multi-order solar EUV spectrograph (MOSES) sounding rocket mission(Montana State University - Bozeman, College of Letters & Science, 2011) Fox, James Lewis; Chairperson, Graduate Committee: Charles C. KankelborgWe have developed a revolutionary spectroscopic technique for solar research in the extreme ultraviolet. This slitless spectrographic technique allows snapshot imaging spectroscopy with data exactly cotemporal and cospectral. I have contributed to the successful realization of an application of this technique in the Multi-Order Solar EUV Spectrograph, MOSES. This instrument launched 2006 Feb 8 as a NASA sounding rocket payload and successfully returned remarkable data of the solar transition region in the He II 304 Ångstrom spectral line. The unique design of this spectrometer allows the study of transient phenomena in the solar atmosphere, with spatial, spectral, and temporal resolution heretofore unachievable in concert, over a wide field of view. The fundamental concepts behind the MOSES spectrometer are broadly applicable to many solar spectral lines and phenomena and the instrument thus represents a new instrumentation technology. The early fruits of this labor are here reported: the first scientific discovery with the MOSES sounding rocket instrument, our observation of a transition region explosive event, phenomena observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548 Ångstrom, 1550 Ångstrom) and Si IV (1393 Ångstrom, 1402 Ångstrom). This explosive event is the first seen in He II 304 Ångstrom. With our novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non-collinear, in directions that are not anti-parallel, in contradiction to standard models of explosive events, which give collinear jets. The jets have sky-plane velocities of order 75km s -¹ and line-of-sight velocities of +75km s -¹ (blue) and -30km s -¹ (red). The core is a region of high non-thermal doppler broadening, characteristic of explosive events, with maximal broadening 380 km s -¹ FWHM. It is possible to resolve the core broadening into red and blue line-of-sight components of maximum doppler velocities +160 km s -¹ and -220 km s -¹. The event lasts more than 150 s. Its properties correspond to the larger, long-lived, and more energetic explosive events observed in other wavelengths.