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Multi Wavelength Analysis of Major Solar Coronal Rains
2013 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Solar eruptions can lead to a number of different events and phenomenon. One such phenomena, which is very rare, is the coronal rain. There are two types of solar coronal rains. The first type follows coronal mass ejections (CME), and is the result of the ejected mass from the eruption not reaching the escape velocity of the Sun, hence falling back down again, commonly along magnetic field lines. The second type is associated with thermal instability. It often follows solar eruptions, like solar flares or CMEs. Coronal rains are explained by solar coronal loops losing their thermal equilibrium, leading to condensations propagating along the paths of the loops, from the apex down toward their foot points. Three coronal rains, one of each type and one with rain of both categories, have been analysed. To understand the morphology and evolution of these events, various sets of data taken by different solar satellites have been analysed. Images from two instruments of the Solar Dynamics Observatory (HMI and AIA), from STEREO, RHESSI and H-alpha were used. The average projected velocities were found to be 70 km/s for the condensation type rain, 160 km/s for turbulent rain of the CME type and 210 km/s for rain falling along magnetic field lines of the CME type. Sizes were found to be largest for the CME type, up to 32 Mm in diameter, with the condensation type blobs being thin and elongated with lengths of up to 14 Mm and 2 Mm wide. An investigation into how deep these rain blobs go into the Sun before they dissolve and can no longer be tracked has been performed with the reached conclusion that when a coronal rain of the CME type follows magnetic field lines into the chromosphere, the deepest levels are likely to be reached. Coronal rains on 2012-04-16 and 2011-06-07 had masses reaching the lower chromosphere, near the photosphere, before they dissolved. No unusual motion or disturbance was observed on the photosphere for the areas where they hit the Sun. The objectives of the study were reached, with three major solar coronal rains analysed and compared.

Place, publisher, year, edition, pages
2013. , 78 p.
Keyword [en]
Physics Chemistry Maths
Keyword [sv]
Fysik, Kemi, Matematik, coronal rain, catastrophic cooling, thermal instability, solar eruption, coronal mass ejection, solar flare, SDO, AIA, HMI, STEREO A, STEREO B
URN: urn:nbn:se:ltu:diva-49299Local ID: 6a78d211-e53e-4850-a03e-2d217f1ff518OAI: diva2:1022646
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Subject / course
Student thesis, at least 30 credits
Educational program
Space Engineering, master's level
Validerat; 20130925 (global_studentproject_submitter)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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