IRIS Nugget
Welcome to the IRIS Science Nuggets: highlights of recent IRIS scientific results for the solar physics community.
{"id":"pod_polito_vanessa_2022-12-01T18:14:47.974Z","submitter":"Huidong Hu","author":"Huidong Hu[1], Ying D. Liu[1], Lakshmi Pradeep Chitta[2], Hardi Peter[2], and Mingde Ding[3]","status":"published","creation-date":"2022-12-01T18:14:48.003Z","last-modified-date":"2022-12-09T18:53:32.05Z","credit":"[1] National Space Science Center, Chinese Academy of Sciences, China. [2] Max Planck Institute for Solar System Research, Germany. [3] School of Astronomy and Space Science, Nanjing University, China.","title":"Spectroscopic and Imaging Observations of Spatially Extended Magnetic Reconnection in the Splitting of a Solar Filament Structure","contentBlocks":[{"type":"text","text":"One%20indicator%20of%20magnetic%20reconnection%20is%20the%20Doppler%20effect%20of%20the%20reconnection%20outflows.%20Previous%20work%20has%20shown%20that%20blue-%20and%20redshifts%20of%20bidirectional%20reconnection%20outflows%20are%20commonly%20observed%20in%20confined%20regions%20on%20the%20Sun%20%28e.g.%2C%20Chifor%20et%20al.%202008%3B%20Tian%20etal.2018%3B%20Ortiz%20et%20al.%202020%29.%20Spatially%20resolved%20spectroscopic%20observations%20covering%20extended%20regions%20in%20the%20solar%20atmosphere%20are%20rare%2C%20and%20thus%20the%20distribution%20of%20reconnection%20outflows%20and%20thermal%20properties%20on%20the%20Sun%20is%20unclear.%0A%0AModels%20and%20imaging%20observations%20suggest%20that%20magnetic%20reconnection%20can%20occur%20internally%20in%20a%20filament%20structure%20and%20is%20associated%20with%20the%20splitting%20and%2For%20partial%20eruption%20of%20the%20filament%20structure%20%28e.g.%2C%20Gilbert%20et%20al.%202001%3B%20Gibson%20%26amp%3B%20Fan%202006%3B%20Tripathi%20et%20al.%202009%3B%20Liu%20et%20al.%202012%29.%20However%2C%20Doppler%20shifts%20of%20bidirectional%20outflows%2C%20as%20definite%20evidence%20for%20reconnection%20in%20solar%20filament%20splitting%2C%20have%20not%20been%20detected%20so%20far.%0A%0AIn%20Hu%20et%20al.%20%282022%29%2C%20we%20report%20a%20magnetic-reconnection%20event%20that%20causes%20the%20splitting%20of%20a%20solar%20filament%20structure%2C%20based%20on%20spatially%20resolved%20spectroscopic%20data%20from%20the%20Interface%20Region%20Imaging%20Spectrograph%20%28IRIS%2C%20De%20Pontieu%20et%20al.%202014%29%20and%20images%20from%20the%20Solar%20Dynamics%20Observatory%20%28SDO%2C%20Pesnell%20et%20al.%202012%29.%0A%0AA%20filament%20structure%20in%20Active%20Region%2012665%20was%20split%20into%20two%20upper%20and%20lower%20branches%20by%20magnetic%20reconnection.%20It%20eventually%20erupted%20partially%2C%20with%20the%20upper%20branch%20ejected%20and%20the%20lower%20branch%20retained.%20The%20evolution%20of%20the%20filament%20structure%20is%20illustrated%20in%20Figure%201%20of%20Hu%20et%20al.%20%282022%29%20and%20in%20animation%20at%20https%3A%2F%2Fyoutu.be%2FaFNowNmP0tQ%20.%20The%20splitting%20by%20reconnection%20was%20captured%20on%20a%20rare%20occasion%20with%20a%20spatially%20resolved%20IRIS%20raster%20scan.%0A%0AFigure%201%20shows%20the%20Doppler%20velocity%2C%20nonthermal%20width%2C%20and%20intensity%20derived%20from%20a%20single%20Gaussian%20fit%20of%20Si%20IV%201393.755%20%26Aring%3B%20line%20profiles%20in%20the%20IRIS%20data.%20Neighboring%20large%20blue-%20and%20redshifts%20of%20%E2%89%B350%20km%2Fs%20in%20the%20brightening%20region%20of%20304%20%26Aring%3B%20between%20the%20two%20filament%20branches%20are%20revealed%2C%20which%20spatially%20correspond%20to%20large%20nonthermal%20widths%20and%20enhanced%20intensities%20%28brightening%29%20of%20the%20Si%20IV%20line.%20These%20are%20the%20signature%20of%20magnetic%20reconnection%2C%20after%20which%20the%20filament%20structure%20is%20split%20into%20two%20branches.%20The%20length%20of%20the%20reconnection%20region%20is%20unprecedentedly%20%7E20%26quot%3B%20%28no%20less%20than%2014%20000%20km%3B%20the%20distance%20between%20the%20two%20crosses%20%28%26quot%3B%2B%26quot%3B%29%20in%20Figure%201%28e%29%29."},{"type":"image","file":"","url":"nuggetvideos/2022/12/01/pod_polito_vanessa_2022-12-01T18%3A14%3A47.974Z/fig2.png","hash":"c554cbb8bf38fc9fac914b5e7a446b86","mimeType":"image/png","caption":"Figure%201.%20Magnetic%20reconnection%20in%20the%20filament%20splitting%20observed%20with%20SDO%20and%20IRIS.%20In%20%28a%29%20the%20rectangle%20denotes%20the%20field%20of%20view%20of%20the%20IRIS%20scan%3B%20%26quot%3BF1%26quot%3B%2C%20%26quot%3BF2%26quot%3B%2C%20and%20the%20arrows%20indicate%20the%20lower%20and%20upper%20filament%20branches.%20In%20%28c%29%20the%20two%20cyan%20slits%20%26quot%3BS1%26quot%3B%20and%20%26quot%3BS2%26quot%3B%20mark%20where%20the%20spectra%20are%20displayed%20in%20Figure%202%28a%29%E2%80%93%28b%29%3B%20the%20black%20dashes%20denote%20where%20on%20the%20slits%20the%20line%20profiles%20are%20plotted%20in%20Figure%202%28c%29%E2%80%93%28d%29."},{"type":"text","text":"As%20displayed%20in%20Figure%202%2C%20blue-%20and%20redshifts%20of%20the%20upward%20and%20downward%20outflows%20are%20detected%20on%20slits%20marked%20in%20Figure%201%28c%29.%20The%20reduction%20of%20the%20overall%20line%20width%20indicates%20that%20the%20line-of-sight%20velocities%20decrease%20remarkably%20after%20the%20bidirectional%20outflows%20have%20left%20the%20reconnection%20site.%20A%20double%20Gaussian%20fit%20of%20the%20profiles%20reveals%20that%20the%20outflow%20velocity%20is%20up%20to%20%7E150%20km%2Fs.%20We%20can%20also%20see%20line%20broadening%20on%20the%20blue%20wing%2C%20at%20%26quot%3BS1-iv%26quot%3B%20and%20%26quot%3BS2-iv%26quot%3B%2C%20several%20arcseconds%20away%20from%20the%20reconnection%20site%2C%20which%20may%20be%20an%20indicator%20of%20turbulence%20that%20is%20induced%20when%20the%20upward%20outflow%20interacts%20with%20the%20upper%20filament%20branch."},{"type":"image","file":"","url":"nuggetvideos/2022/12/01/pod_polito_vanessa_2022-12-01T18%3A14%3A47.974Z/fig3.png","hash":"552b3817151a9550c3fec5183ab884ee","mimeType":"image/png","caption":"Figure%202.%20Spectra%20of%20the%20bidirectional%20outflows%20from%20the%20reconnection%20site%20at%20positions%20defined%20in%20Figure%201%28c%29.%20In%20%28c%29%E2%80%93%28d%29%2C%20the%20black%20curves%20are%20the%20observed%20profiles%3B%20the%20cyan%20curves%20represent%20the%20total%20fits%3B%20and%20the%20red%20and%20blue%20curves%20plot%20the%20two%20Gaussian%20components."},{"type":"text","text":"Figure%203%20presents%20the%20differential-emission-measure%20%28DEM%29%20analysis%20of%20the%20reconnection%20region.%20The%20DEM%20analysis%20shows%20that%20the%20temperature%20during%20the%20reconnection%20is%20%7E14%20MK%2C%20%7E9%20MK%20higher%20than%20that%20before%20the%20reconnection.%20The%20electron%20density%20is%20%5Cbegin%7Bequation%7D%20%5Csim%203.9%20%5Ctimes%2010%5E%7B10%7D%5C%20%5Cmathrm%7Bcm%7D%5E%7B-3%7D%20%5Cend%7Bequation%7D%2C%20about%20twice%20that%20before%20the%20reconnection.%20By%20assuming%20a%20volume%20size%2C%20the%20total%20thermal%20energy%20is%20estimated%20to%20be%20%5Cbegin%7Bequation%7D%20%5Csim%201.3%20%5Ctimes%2010%5E%7B27%7D%20%5Cend%7Bequation%7D%20ergs%2C%20which%20is%20about%20ten%20times%20the%20kinetic%20energy."},{"type":"image","file":"","url":"nuggetvideos/2022/12/01/pod_polito_vanessa_2022-12-01T18%3A14%3A47.974Z/fig4.png","hash":"d02381d36c7da2cbe9ca7abed19cae3b","mimeType":"image/png","caption":"Figure%203.%20Differential%20emission%20measure%20%28DEM%29%20and%20emission%20measure%20%28EM%29%20of%20the%20reconnection%20region%20based%20on%20SDO%2FAIA%20observations.%20The%20temporal%20DEM%20in%20%28c%29%20is%20averaged%20over%20the%20four%20pixels%20specified%20by%20the%20square%20in%20%28b%29."},{"type":"text","text":"We%20have%20provided%20spectroscopic%20evidence%20for%20the%20splitting%20of%20a%20filament%20structure%20by%20magnetic%20reconnection.%20The%20reconnection%20is%20in%20an%20extended%20region%20with%20an%20unprecedented%20length.%20The%20thermal%20energy%20overwhelmingly%20dominates%20the%20kinetic%20energy%20in%20this%20reconnection%20event.%0A%0AFor%20details%2C%20please%20see%20Hu%20et%20al.%20%282022%29."}],"references":["<a href=\"https://ui.adsabs.harvard.edu/abs/2001ApJ...549.1221G/abstract\">Gilbert, H. R., et al. ApJ 549.2 (2001): 1221.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2006ApJ...637L..65G/abstract\">Gibson, S. E., and Y. Fan. ApJL 637.1 (2006): L65.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2008A%26A...481L..57C/abstract\">Chifor, C., et al. A&A 481.1 (2008): L57-L60.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2009A%26A...498..295T/abstract\">Tripathi, D., et al. A&A 498.1 (2009): 295-305.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2012ApJ...756...59L/abstract\">Liu, R., et al. ApJ 756.1 (2012): 59.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2012SoPh..275....3P/abstract\">Pesnell, W. D., et al. SoPh 275.1 (2012): 3-15.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2014SoPh..289.2733D/abstract\">De Pontieu, B., et al. SoPh 289.7 (2014): 2733-2779.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2018ApJ...854..174T/abstract\">Tian, H., et al. ApJ 854.2 (2018): 174.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2020A%26A...633A..58O/abstract\">Ortiz, A., et al. A&A 633 (2020): A58.</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2022ApJ...940L..12H/abstract\">Hu, H., et al. ApJL 940.1 (2022): L12.</a>"],"pubDate":"2022-12-09T18:53:37.592Z"}