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تسجيل مستخدم جديدH$alpha$ and EUV observations of a partial CME
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We have obtained H$alpha$ high spatial and time resolution observations of the upper solar chromosphere and supplemented these with multi-wavelength observations from the Solar Dynamic Observatory (SDO) and the {it Hinode} ExtremeUltraviolet Imaging Spectrometer (EIS). The H$alpha$ observations were conducted on 11 February 2012 with the Hydrogen-Alpha Rapid Dynamics Camera (HARDcam) instrument at the National Solar Observatorys Dunn Solar Telescope. Our H$alpha$ observations found large downflows of chromospheric material returning from coronal heights following a failed prominence eruption. We have detected several large condensations (blobs) returning to the solar surface at velocities of $approx$200 km s$^{-1}$ in both H$alpha$ and several SDO AIA band passes. The average derived size of these blobs in H$alpha$ is 500 by 3000 km$^2$ in the directions perpendicular and parallel to the direction of travel, respectively. A comparison of our blob widths to those found from coronal rain, indicate there are additional smaller, unresolved blobs in agreement with previous studies and recent numerical simulations. Our observed velocities and decelerations of the blobs in both H$alpha$ and SDO bands are less than those expected for gravitational free-fall and imply additional magnetic or gas pressure impeding the flow. We derived a kinetic energy $approx$2 orders of magnitude lower for the main eruption than a typical CME, which may explain its partial nature.
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