IRIS Nugget
Welcome to the IRIS Science Nuggets: highlights of recent IRIS scientific results for the solar physics community.
{"id":"pod_polito_vanessa_2021-08-19T19:00:20.335Z","submitter":"Katharine Reeves","author":"Katharine K. Reeves [1] , Vanessa Polito [2,3] , Bin Chen [4] , Giselle Galan [1,5], Sijie Yu [4] , Wei Liu [2,3,6], and Gang Li [7]","status":"published","creation-date":"2021-08-19T19:00:20.343Z","last-modified-date":"2021-09-13T19:45:07.775Z","credit":"[1] Harvard-Smithsonian Center for Astrophysics, [2] Bay Area Environmental Research Institute, [3] Lockheed Martin Solar and Astrophysics Laboratory, [4] Center for Solar-Terrestrial Research, New Jersey Institute of Technology, [5] Department of Physics, Massachusetts Institute of Technology, [6] W.W. Hansen Experimental Physics Laboratory, Stanford University, [7] Department of Space Science and CSPAR, University of Alabama in Huntsville","title":"Hot Plasma Flows and Oscillations in the Loop-top Region During the 2017 September 10 X8.2 Solar Flare","contentBlocks":[{"type":"text","text":"On%20September%2010%202017%2C%20an%20X8%20flare%20and%20an%20associated%20spectacular%20eruption%20occurred%20on%20the%20west%20limb%20of%20the%20Sun.%20%20This%20event%20was%20observed%20by%20IRIS%2C%20AIA%2C%20EOVSA%20and%20Hinode.%20%20The%20IRIS%20pointing%20was%20just%20south%20of%20the%20main%20cusp-shaped%20loop%20structure%20visible%20in%20AIA%2C%20but%20it%20did%20capture%20most%20of%20the%20flare%20arcade%20on%20the%20limb%2C%20as%20shown%20in%20Figure%201.%20%20Shortly%20after%20the%20eruption%2C%20at%2015%3A55%20UT%2C%20microwave%20emission%20from%20EOVSA%20extends%20south%20from%20the%20bright%20flare%20loops%2C%20as%20seen%20in%20the%20top%20panel%20of%20Figure%201.%20At%20this%20time%2C%20there%20is%20some%20faint%20emission%20in%20the%20AIA%20131%20%26Aring%3B%20channel%20close%20to%20the%20limb%2C%20and%20some%20strands%20of%20emission%20in%20the%20IRIS%201330%20%26Aring%3B%20channel%20that%20look%20similar%20to%20coronal%20rain.%20As%20the%20eruption%20progresses%20%28lower%20panels%20of%20Figure%201%29%2C%20faint%2C%20diffuse%20emission%20is%20seen%20extending%20to%20the%20south%20of%20the%20bright%20flare%20arcade%20in%20the%20AIA%20131%20%26Aring%3B%20and%20193%20%26Aring%3B%20channels%20%28and%20also%20in%20the%20AIA%2094%20%26Aring%3B%20and%20335%20%26Aring%3B%20channels%2C%20which%20are%20not%20shown%29%2C%20and%20in%20the%20IRIS%201330%20%26Aring%3B%20SJI%20image."},{"type":"image","file":"","url":"nuggetvideos/2021/08/19/pod_polito_vanessa_2021-08-19T19%3A00%3A20.335Z/fig1.jpg","hash":"23edcb8ba7749c46547c04a23fe0d156","mimeType":"image/jpeg","caption":"Figure%201%3A%20Summary%20of%20AIA%20and%20IRIS%20images%3A%20The%20AIA%20131%20%26Aring%3B%2C193%20%26Aring%3B%20and%20IRIS%20SJI%201330%20%26Aring%3B%20channels%20during%20the%20flare.%20White%20contours%20show%20EOVSA%20microwave%20emission%20at%202.9%20GHz%20at%2050%25%2C%2075%25%2C%20and%2090%25%20intensity.%20The%20yellow%20and%20white%20boxes%20show%20the%20region%20of%20IRIS%20and%20EIS%20slit%20coverage%20examined%20in%20this%20work%2C%20and%20the%20yellow%20stars%20and%20white%20diamond%20show%20the%20locations%20of%20blue-shifted%20regions."},{"type":"text","text":"We%20examine%20in%20detail%20the%20data%20from%20the%20IRIS%20Fe%20XXI%20line%2C%20which%20is%20a%20coronal%20line%20that%20is%20formed%20at%20about%2010%20MK.%20%20For%20the%20IRIS%20Fe%20XXI%20data%2C%20a%20Gaussian%20is%20fit%20to%20the%20spectrum%20in%20every%20pixel%20along%20the%20slit%2C%20%20and%20Figure%202%20shows%20the%20intensity%2C%20%20the%20Doppler%20velocity%20and%20the%20non-thermal%20velocity%20for%208-step%20rasters.%20During%20the%20period%20from%2016%3A05%20-%2016%3A15%20UT%2C%20we%20find%20that%20faint%20blue-shifted%20regions%20appear%20at%20the%20top%20of%20the%20flare%20loops%2C%20indicating%20plasma%20flows%20of%2020-60%20km%2Fs.%20Loop%20top%20regions%20with%20blue%20shifts%20shown%20in%20Figure%202%20oscillate%20in%20Doppler%20shift%20as%20a%20function%20of%20time%2C%20as%20shown%20in%20Figure%203.%20The%20observed%20periods%20are%20fairly%20similar%2C%20on%20the%20order%20of%20400%20s%2C%20and%20there%20is%20no%20obvious%20correlation%20between%20the%20period%20of%20the%20oscillation%20and%20loop%20length%2C%20which%20rules%20out%20standing%20slow%20mode%20waves%20as%20the%20mechanism%20for%20the%20oscillation."},{"type":"image","file":"","url":"nuggetvideos/2021/08/19/pod_polito_vanessa_2021-08-19T19%3A00%3A20.335Z/fig2.jpg","hash":"e8a5046fda0b81adee1ca1b8a16ff631","mimeType":"image/jpeg","caption":"Figure%202.%20The%20intensity%20%28top%20row%29%2C%20the%20Doppler%20velocity%20%28middle%20row%29%2C%20and%20the%20nonthermal%20velocity%20%28bottom%20row%29%20for%20pixels%20along%20the%20slit%20in%20eight-step%20rasters%2C%20corresponding%20to%20the%20yellow%20box%20shown%20in%20Figure%201.%20The%20time%20given%20in%20the%20top%20row%20is%20the%20time%20for%20the%20first%20raster%20step.%20Color%20bars%20for%20each%20row%20are%20shown%20to%20the%20right.%20Boxes%20show%20the%20pixels%20that%20are%20averaged%20together%20to%20get%20average%20Doppler%20shifts%20in%20Figure%203."},{"type":"image","file":"","url":"nuggetvideos/2021/08/19/pod_polito_vanessa_2021-08-19T19%3A00%3A20.335Z/fig5.jpg","hash":"29239dc9232e6c3dc008697f485fce75","mimeType":"image/jpeg","caption":"Figure%203%3A%20IRIS%20Doppler%20shifts%20as%20a%20function%20of%20time%20for%20the%20pixels%20in%20the%20boxes%20shown%20in%20Figure%202.%20Times%20have%20been%20shifted%20so%20that%20the%20main%20blueshift%20for%20each%20time%20series%20occurs%20at%20the%20same%20time.%20For%20each%20plot%2C%20thin%20gray%20lines%20indicate%20the%20time%20series%20for%20each%20pixel%20in%20the%20box%2C%20averages%20for%20all%20the%20pixels%20in%20the%20box%20are%20shown%20as%20a%20thick%20black%20line%2C%20and%20a%20fit%20to%20the%20average%20using%20a%20damped%20oscillation%20is%20shown%20as%20a%20thick%20red%20line."},{"type":"text","text":"A%20potential%20scenario%20explaining%20our%20observations%20based%20on%20the%20modeling%20of%20Takasao%20%26amp%3B%20Shibata%20%282016%29%20is%20shown%20in%20Figure%204.%20First%2C%20magnetic%20fields%20are%20reconnected%20and%20electrons%20are%20accelerated%2C%20creating%20a%20microwave%20source%20at%20the%20base%20of%20the%20current%20sheet%20with%20a%20nearly%20face-on%20viewing%20perspective%20%28as%20described%20in%20detail%20in%20Chen%20et%20al.%202020%29%20and%20causing%20brightenings%20at%20the%20flare%20ribbons.%20As%20the%20reconnection%20outflows%20impinge%20on%20the%20loops%20below%2C%20they%20create%20a%20horn-shaped%20magnetic%20field%20line%20that%20oscillates%20due%20to%20the%20rebounding%20reconnection%20outflow%20%28or%20%E2%80%9Cbackflow%E2%80%9D%29%2C%20creating%20magnetoacoustic%20waves.%20Takasao%20%26amp%3B%20Shibata%20%282016%29%20refer%20to%20this%20structure%20as%20a%20%E2%80%9Cmagnetic%20tuning%20fork%2C%E2%80%9D%20because%20of%20its%20similarity%20to%20a%20musical%20tuning%20fork%20that%20vibrates%20and%20generates%20sound%20waves.%20Oscillations%20in%20this%20region%20cause%20the%20Doppler%20oscillations%20that%20we%20observe%20in%20the%20IRIS%20data.%20Additionally%2C%20a%20dense%20blob%20of%20material%20is%20created%20within%20the%20arms%20of%20the%20magnetic%20tuning%20fork%20due%20to%20the%20compression%20of%20the%20reconnection%20flow%2C%20corresponding%20to%20the%20blob%20of%20hot%20material%20observed%20in%20the%20IRIS%201330%20%26Aring%3B%20and%20AIA%20131%20%26Aring%3B%20channels."},{"type":"image","file":"","url":"nuggetvideos/2021/08/19/pod_polito_vanessa_2021-08-19T19%3A00%3A20.335Z/fig11.jpg","hash":"28e24ed1d0653412a7083c749c346ba8","mimeType":"image/jpeg","caption":"Figure%204%3A%20A%20cartoon%20showing%20a%20possible%20scenario%20to%20describe%20the%20observed%20oscillations.%20Drawing%20%28a%29%20shows%20the%20early%20phase%20of%20the%20eruption%2C%20when%20the%20microwave%20source%20is%20visible%2C%20as%20in%20Figure%201.%20Drawing%20%28b%29%20shows%20the%20formation%20of%20the%20%E2%80%9Cmagnetic%20tuning%20fork%E2%80%9D%20caused%20by%20reconnection%20outflows%20hitting%20the%20closed%20loops%20below%20and%20causing%20the%20Doppler%20oscillations%20shown%20in%20Figure%203.%20Drawing%20%28c%29%20shows%20the%20relaxed%20state%20of%20the%20flare%20arcade%2C%20when%20the%20oscillations%20have%20stopped%20and%20the%20loops%20have%20cooled.%20The%20AIA%20131%20%26Aring%3B%20image%20at%20the%20lower%20left%20shows%20the%20orientation%20of%20the%20reconnecting%20arcade%20and%20the%20location%20of%20the%20dense%20%E2%80%9Cblob%E2%80%9D."}],"references":["<a href=\"https://ui.adsabs.harvard.edu/abs/2020ApJ...895L..50C/abstract\">Chen, B. et al. The Astrophysical Journal Letters, Volume 895, Issue 2, id.L50, 10 pp. (2020)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2016ApJ...823..150T/abstract\">Takasao & Shibata, The Astrophysical Journal, Volume 823, Issue 2, article id. 150, 11 pp. (2016).</a>","","","","","","","",""],"pubDate":"2021-09-13T19:45:13.35Z"}