Nicholeen M. Viall, James A. Klimchuk
One of the outstanding problems in all of space science is uncovering how the solar corona is heated to temperatures greater than 1 MK. Though studied for decades, one of the major difficulties in solving this problem has been unraveling the line of sight (LOS) effects in the observations. The corona is optically thin, so a single pixel measures counts from as many as tens of thousands of independently heated flux tubes, all along that pixels LOS. In this paper we model individual pixels imaging the active region corona in the Extreme Ultraviolet. If LOS effects are not properly taken into account, erroneous conclusions regarding both coronal heating and coronal dynamics may be reached. We model the corona as a LOS integration of many thousands of completely independently heated flux tubes. We demonstrate that despite the superposition of randomly heated flux tubes, nanoflares leave distinct signatures in light curves observed with multiwavelength and high time cadence data, such as those data taken with the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. These signatures are readily detected with the time lag analysis technique of Viall and Klimchuk, 2012. Steady coronal heating leaves a different and equally distinct signature that is also revealed by the technique.
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http://arxiv.org/abs/1304.5439
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