%0 Journal Article %1 citeulike:14264405 %A Kuhar, Matej %A Krucker, Säm %A Hannah, Iain G. %A Glesener, Lindsay %A Saint-Hilaire, Pascal %A Grefenstette, Brian W. %A Hudson, Hugh S. %A White, Stephen M. %A Smith, David M. %A Marsh, Andrew J. %A Wright, Paul J. %A Boggs, Steven E. %A Christensen, Finn E. %A Craig, William W. %A Hailey, Charles J. %A Harrison, Fiona A. %A Stern, Daniel %A Zhang, William W. %D 2017 %J The Astrophysical Journal %K imported %N 1 %P 6+ %R 10.3847/1538-4357/835/1/6 %T Evidence of Significant Energy Input in the Late Phase of a Solar Flare from NuSTAR X-Ray Observations %U http://dx.doi.org/10.3847/1538-4357/835/1/6 %V 835 %X We present observations of the occulted active region AR12222 during the third NuSTAR solar campaign on 2014 December 11, with concurrent \em SDO/AIA and FOXSI-2 sounding rocket observations. The active region produced a medium size solar flare one day before the observations, at \$\sim18\$UT on 2014 December 10, with the post-flare loops still visible at the time of NuSTAR observations. The time evolution of the source emission in the SDO/AIA \$335\AA\$ channel reveals the characteristics of an extreme-ultraviolet late phase event, caused by the continuous formation of new post-flare loops that arch higher and higher in the solar corona. The spectral fitting of NuSTAR observations yields an isothermal source, with temperature \$3.8-4.6\$ MK, emission measure \$0.3-1.8 10^46 cm^-3\$, and density estimated at \$2.5-6.0 10^8 cm^-3\$. The observed AIA fluxes are consistent with the derived NuSTAR temperature range, favoring temperature values in the range \$4.0-4.3\$ MK. By examining the post-flare loops' cooling times and energy content, we estimate that at least 12 sets of post-flare loops were formed and subsequently cooled between the onset of the flare and NuSTAR observations, with their total thermal energy content an order of magnitude larger than the energy content at flare peak time. This indicates that the standard approach of using only the flare peak time to derive the total thermal energy content of a flare can lead to a large underestimation of its value.

@article{citeulike:14264405, abstract = {We present observations of the occulted active region AR12222 during the third {\em NuSTAR} solar campaign on 2014 December 11, with concurrent {\em SDO/}AIA and {\em FOXSI-2} sounding rocket observations. The active region produced a medium size solar flare one day before the observations, at \$\sim18\$UT on 2014 December 10, with the post-flare loops still visible at the time of {\em NuSTAR} observations. The time evolution of the source emission in the {\em SDO/}AIA \$335\textrm{\AA}\$ channel reveals the characteristics of an extreme-ultraviolet late phase event, caused by the continuous formation of new post-flare loops that arch higher and higher in the solar corona. The spectral fitting of {\em NuSTAR} observations yields an isothermal source, with temperature \$3.8-4.6\$ MK, emission measure \$0.3-1.8 \times 10^{46}\textrm{ cm}^{-3}\$, and density estimated at \$2.5-6.0 \times 10^8 \textrm{ cm}^{-3}\$. The observed AIA fluxes are consistent with the derived {\em NuSTAR} temperature range, favoring temperature values in the range \$4.0-4.3\$ MK. By examining the post-flare loops' cooling times and energy content, we estimate that at least 12 sets of post-flare loops were formed and subsequently cooled between the onset of the flare and {\em NuSTAR} observations, with their total thermal energy content an order of magnitude larger than the energy content at flare peak time. This indicates that the standard approach of using only the flare peak time to derive the total thermal energy content of a flare can lead to a large underestimation of its value.}, added-at = {2019-03-25T08:20:55.000+0100}, archiveprefix = {arXiv}, author = {Kuhar, Matej and Krucker, S\"{a}m and Hannah, Iain G. and Glesener, Lindsay and Saint-Hilaire, Pascal and Grefenstette, Brian W. and Hudson, Hugh S. and White, Stephen M. and Smith, David M. and Marsh, Andrew J. and Wright, Paul J. and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Hailey, Charles J. and Harrison, Fiona A. and Stern, Daniel and Zhang, William W.}, biburl = {https://www.bibsonomy.org/bibtex/2f9f52c2b9820547cab178f2a35463ff7/ericblackman}, citeulike-article-id = {14264405}, citeulike-linkout-0 = {http://arxiv.org/abs/1701.07759}, citeulike-linkout-1 = {http://arxiv.org/pdf/1701.07759}, citeulike-linkout-2 = {http://dx.doi.org/10.3847/1538-4357/835/1/6}, day = 26, doi = {10.3847/1538-4357/835/1/6}, eprint = {1701.07759}, interhash = {ed62774f6161418d49377c5b509166f9}, intrahash = {f9f52c2b9820547cab178f2a35463ff7}, issn = {1538-4357}, journal = {The Astrophysical Journal}, keywords = {imported}, month = jan, number = 1, pages = {6+}, posted-at = {2017-01-29 07:38:26}, priority = {2}, timestamp = {2019-03-25T08:20:55.000+0100}, title = {{Evidence of Significant Energy Input in the Late Phase of a Solar Flare from NuSTAR X-Ray Observations}}, url = {http://dx.doi.org/10.3847/1538-4357/835/1/6}, volume = 835, year = 2017 }