{"id":"pod_polito_vanessa_2021-05-18T22:48:19.507Z","submitter":"1. Department of Physics, DSB Campus, Kumaun University, Nainital, India 2. LESIA, Observatoire de Paris, Meudon, France 3. Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic","author":"Reetika Joshi (1)","status":"published","creation-date":"2021-05-18T22:48:19.512Z","last-modified-date":"2021-06-14T16:54:35.495Z","credit":"Brigitte Schmieder (2), Guillaume Aulanier (2), Petr Heinzel (3), Ramesh Chandra (1)","title":"Sandwich model for multi thermal atmosphere of a mini-solar flare during jet reconnection","contentBlocks":[{"type":"text","text":"The%20Interface%20Region%20Imaging%20Spectrograph%20%28IRIS%29%20has%20revealed%20several%20transient%20small-scale%20phenomena%20in%20the%20solar%20atmosphere%2C%20such%20as%20%0AIRIS%20bombs%20%28IBs%2C%20Peter%20et%20al.%2C%202014%2C%20Grubecka%20et%20al.%2C%202016%29%20subclass%20of%20solar%20Ultraviolet%20%28UV%29%20bursts%20%28Young%20et%20al.%2C%202018%2C%20De%20Pontieu%2C%20et%20al.%2C%202021%29%2C%20explosive%20events%20%28Kim%20et%20al.%202015%29%2C%20blow%20jets%20%28Shen%20et%20al.%202017%29%2C%20and%20bidirectional%20outflow%20jets%20%28Ruan%20et%20al.%2C%202019%29.%20Solar%20jets%20are%20commonly%20observed%20with%20IRIS%20and%20the%20multi-wavelength%20AIA%20telescope.%20The%20characteristics%20of%20such%20jets%20can%20vary%3A%20their%20velocity%20can%20reach%20between%20100%20and%20%20400%20km%2Fs%20and%20their%20typical%20length%20can%20range%20between%2050%20and%20100%20Mm%20%28Joshi%20et%20al.%202020a%29.%20The%20IRIS%20spectroscopic%20and%20imaging%20observations%20of%20jets%20have%20also%20revealed%20bidirectional%20outflows%20in%20transition%20region%20lines%20at%20the%20base%20of%20the%20jets%2C%20thereby%20implying%20explosive%20magnetic%20reconnection%20processes.%0A%0AIn%20this%20study%2C%20we%20analysed%20the%20fine%20structure%20and%20dynamics%20of%20the%20plasma%20at%20the%20base%20of%20a%20jet%20forming%20a%20mini-flare%20%28GOES%20B6.7%29%20between%20two%20emerging%20magnetic%20fluxes%20%28EMFs%29%2C%20as%20observed%20with%20IRIS%20and%20SDO%20%28Joshi%20et%20al.%2C%202021%29.%20On%20March%2022%2C%202019%20between%2001%3A43%3A27%20UT%20and%2002%3A42%3A30%20UT%2C%20IRIS%20was%20targeting%20the%20base%20of%20the%20jet%20%20in%20the%20NOAA%20AR%2012736.%20When%20the%20jet%20appeared%2C%20IRIS%20acquired%20slit%20jaw%20images%20%28SJIs%29%20in%20two%20passbands%3A%201330%20%26Aring%3B%2C%20dominated%20by%20the%20C%20II%20lines%2C%20and%202796%20%26Aring%3B%2C%20dominated%20by%20the%20Mg%20II%20k%20line%20%28Joshi%20et%20al.%2C%202020b%29.%20The%20jet%2C%20which%20was%20accompanied%20by%20a%20cool%20surge%2C%20was%20observed%20for%20one%20hour%20in%20different%20AIA%20and%20IRIS%20wavebands.%20An%20overview%20of%20the%20AR%2012736%20with%20the%20mini-flare%20is%20presented%20in%20Fig.%201.%20Panel%20%28a%29%20shows%20the%20full%20disk%20image%20of%20the%20Sun%20and%20the%20AR%20under%20study%2C%20while%20panel%20%28b%29%20shows%20a%20zoom%20view%20of%20the%20304%20%26Aring%3B%20map%20overlaid%20with%20the%20HMI%20magnetic%20field%20contours%20of%20the%20emerging%20magnetic%20flux%20%28EMF%29.%20The%20initiation%20of%20the%20jet%20and%20surge%20occurred%20between%20the%20opposite%20polarities%20of%20the%20two%20EMFs%20%28panel%20%28b%29%29.%20This%20region%20is%20zoomed%20in%20panel%20%28c%29%2C%20which%20also%20shows%20the%20bright%20point%20at%20the%20footpoint%20of%20the%20jet.%20IRIS%20observed%20the%20AR%20with%20a%20four-step%20raster%20and%20the%20slit%20position%201%20crossed%20the%20reconnection%20region%20in%20the%20bright%20point."},{"type":"image","file":"","url":"nuggetvideos/2021/05/18/pod_polito_vanessa_2021-05-18T22%3A48%3A19.507Z/Screenshot 2021-06-08 at 12.56.31 PM.png","hash":"b3711a090fd0b77957197e3f75518c89","mimeType":"image/png","caption":"Fig.%201%3A%20Observations%20of%20the%20solar%20jet%20and%20surge%20in%20AIA%20304%20%26Aring%3B%20and%20IRIS%20SJI%20CII%201330%20%26Aring%3B%20on%20March%2022%2C%202019.%20Panel%20a%20shows%20the%20full%20disk%20image%20of%20the%20Sun%2C%20and%20the%20blue%20rectangular%20box%20the%20AR%20which%20is%20zoomed%20in%20panel%20b.%20In%20panel%20b%20the%20green%20contours%20represent%20positive%20magnetic%20polarity%20and%20blue%20contours%20negative%20magnetic%20polarity%20%28%2B%2F-%20300%20Gauss%29.%20Magnetic%20reconnection%20occurred%20between%20two%20emerging%20magnetic%20flux%20%28EMF%29%20regions%20initiating%20the%20jet%20and%20surge.%20The%20reconnection%20site%20%28bright%20point%29%20is%20crossed%20by%20the%20IRIS%20slit%20position%201%20indicated%20by%20the%20green%20arrow%20in%20panel%20c."},{"type":"text","text":"Figure%202%20shows%20an%20overview%20of%20the%20spatio-temporal%20analysis%20of%20the%20IRIS%20spectra%20in%20the%20Mg%20II%2C%20C%20II%2C%20and%20Si%20IV%20lines.%20During%20the%20reconnection%2C%20the%20IRIS%20spectra%20of%20the%20mini-flare%20show%20absorption%20in%20line%20cores%20%28Fig.%202%20d-f%29%20corresponding%20to%20the%20dark%20material%20seen%20in%20the%20AIA%20304%20%26Aring%3B%20images%20%28see%20between%20the%20two%20arrows%20in%20Fig.%202%20a-c%29.%20This%20suggests%20the%20presence%20of%20cool%20plasma%20above%20hotter%20plasma.%20The%20Doppler%20velocities%20from%20the%20Mg%20II%20lines%20were%20computed%20using%20a%20cloud%20model%20technique.%20According%20to%20this%20technique%2C%20the%20Mg%20II%20large%20extended%20blueshift%20profiles%20have%20been%20interpreted%20as%20being%20due%20to%20the%20presence%20of%20two%20cool%20clouds%20over%20the%20reconnection%20site%20with%20velocities%20of%20around%20-300%20km%2Fs%20and%20-36%20km%2Fs%20respectively%20%28Fig.%203%20c%20in%20right%20panel%29.%20The%20large%20%20Si%20IV%20and%20C%20II%20line%20width%20indicates%20%20similar%20velocities%20%28Fig.%203%20a%2C%20b%29.%20%20We%20speculate%20that%20one%20part%20of%20the%20trapped%20cool%20material%20could%20have%20been%20ejected%20with%20a%20low%20velocity%20while%20the%20other%20part%20was%20ejected%20with%20a%20fast%20upwards%20velocity%20during%20approximately%20one%20minute.%20The%20presence%20of%20such%20cool%20plasma%20over%20the%20heated%20atmosphere%20at%20the%20reconnection%20site%20is%20also%20confirmed%20by%20the%20presence%20of%20%20photospheric%20lines%20%20%28Fe%20II%20and%20Ni%20II%29%20visible%20in%20absorption%20features%20across%20%20the%20Si%20IV%20profiles%20%28Fig.%203%20a%29.%20The%20presence%20of%20such%20lines%20superimposed%20on%20emission%20lines%20%20implies%20also%20%20that%20cool%20%20material%20is%20stacked%20on%20top%20of%20hot%20material."},{"type":"image","file":"","url":"nuggetvideos/2021/05/18/pod_polito_vanessa_2021-05-18T22%3A48%3A19.507Z/Screenshot 2021-05-23 at 8.53.20 PM.png","hash":"87de82eed0b98ee453c41cfbcfea1a06","mimeType":"image/png","caption":"Fig.%202%3A%20Jet%20reconnection%20base%20%28UV%20burst%20or%20mini-flare%29%20and%20jet%20evolution.%20First%20column%3A%20images%20in%20AIA%20304%20%26Aring%3B.%20Second%2C%20third%2C%20and%20last%20columns%20show%20IRIS%20spectra%20of%20the%20jet%20reconnection%20site%20%28UV%20burst%29%20at%20the%20slit%20position%201%20%28shown%20by%20cyan%20arrows%20in%20panel%20a-c%29%20in%20the%20Mg%20II%20k%2C%20C%20II%2C%20and%20Si%20IV%20lines%20respectively."},{"type":"text","text":"To%20explain%20these%20observations%2C%20we%20propose%20a%20stratification%20model%20for%20the%20white%20light%2C%20mini-flare%20atmosphere%20where%20multiple%20layers%20at%20different%20temperatures%20are%20found%20along%20the%20line%20of%20sight%20%28LOS%29%20in%20a%20reconnection%20current%20sheet%20%28Fig.%203%2C%20left%20panel%29.%20Emission%20in%20the%20temperature%20minimum%20region%20is%20also%20detected%20with%20the%20AIA%201600%20%26Aring%3B%20and%201700%20%26Aring%3B%20filters%2C%20confirming%20the%20presence%20of%20heating%20in%20the%20low%20atmosphere.%20The%20Mg%20II%20and%20C%20II%20lines%20are%20good%20diagnostics%20for%20detecting%20plasma%20at%20chromospheric%20temperature%20%28T%20%26lt%3B%2020000%20K%29%2C%20Si%20IV%20at%20transition%20region%20temperature.%20We%20identified%20bilateral%20outflows%20in%20these%20lines%20%20%28Fig.%202%20at%2002%3A04%3A28%20%20UT%29%20%20within%20a%20bald%20patch%20region%20%28BP-%20where%20the%20magnetic%20field%20lines%20are%20tangent%20to%20the%20solar%20surface%29%20in%20HMI%20vector%20magnetograms.%20The%20BP%20current%20sheet%20is%20transformed%20to%20an%20%26quot%3BX%26quot%3B-point%20current%20sheet%20during%20the%20reconnection%2C%20which%20is%20responsible%20for%20the%20hot%20plasma%20detected%20in%20the%20AIA%20filters%20%2894%20%26Aring%3B%20-%20211%20%26Aring%3B%29%2C%20as%20shown%20by%20the%20OHM%20MHD%20model%20%28Joshi%20et%20al.%2C%202020b%29.%20%20The%20presence%20of%20cool%20plasma%20above%20transition%20region%20temperature%20plasma%20in%20the%20reconnection%20site%20could%20be%20caused%20by%20the%20ejected%20cool%20clouds%20from%20the%20BP.%20We%20note%20that%20this%20event%20is%20embedded%20in%20the%20corona.%20This%20demonstrates%20the%20possibility%20of%20producing%20different%20velocities%20and%20temperatures%20across%20successive%20layers%20of%20the%20atmosphere%20in%20the%20current%20sheet.%20This%20is%20the%20first%20time%20that%20we%20could%20quantify%20the%20fast%20speed%20%28possibly%20super%20Alfv%26eacute%3Bnic%20flows%29%20of%20cool%20clouds%20which%20were%20ejected%20perpendicularly%20to%20the%20jet%20direction%20via%20the%20cloud%20model%20technique.%20We%20speculate%20that%20the%20ejected%20clouds%20originated%20from%20plasma%20which%20was%20inserted%20between%20the%20two%20EMFs%20in%20the%20BP%20before%20reconnection%20or%20that%20are%20caused%20by%20cool%20upflow%20material%20similar%20to%20a%20surge%20during%20reconnection."},{"type":"image","file":"","url":"nuggetvideos/2021/05/18/pod_polito_vanessa_2021-05-18T22%3A48%3A19.507Z/Screenshot 2021-05-23 at 8.54.57 PM.png","hash":"e1bca2e46521be11010e0faf8788f94","mimeType":"image/png","caption":"Fig.%203%3A%20Left%20panel%3A%20Model%20of%20multi-layers%20atmosphere%20of%20a%20mini-flare%20at%20the%20time%20of%20reconnection%20in%20a%20bald%20patch%20region.%20The%20LOS%20successively%20crosses%20cool%20and%20hot%20layers%20%28white%20for%20the%20temperature%20minimum%20region%2C%20yellow%20for%20chromosphere%20up%20to%20transition%20region%20temperatures%2C%20red%20for%20coronal%20temperatures%29.%20Right%20panel%3A%20Line%20profiles%20at%20the%20reconnection%20point%20in%20Si%20IV%2C%20C%20II%2C%20and%20in%20Mg%20II%20lines.%20The%20presence%20of%20photospheric%20lines%20viewed%20in%20absorption%20%28Ni%20II%201393.33%20%26Aring%3B%20and%20Fe%20II%201393.589%20%26Aring%3B%29%20are%20indicated%20by%20red%20arrows.%20Self-absorption%20of%20the%20Si%20IV%20line%20blended%20by%20a%20Fe%20II%20line%20is%20indicated%20by%20the%20black%20arrow%20in%20the%20top%20right%20panel."},{"type":"text","text":"This%20work%20is%20done%20in%20collaboration%20with%20%20Brigitte%20Schmieder%2C%20Akiko%20Tei%2C%20Guillaume%20Aulanier%2C%20Juraj%20L%26ouml%3Brin%C4%8D%26iacute%3Bk%2C%20Ramesh%20Chandra%2C%20Petr%20Heinzel%2C%20V%26eacute%3Bronique%20Bommier%20and%20published%20as%20%20Joshi%20et%20al.%2C%202020b%20%20and%20%20Joshi%20et%20al.%2C%202021."}],"references":["<a href=\"https://ui.adsabs.harvard.edu/abs/2021SoPh..296...84D/abstract\">De Pontieu, B., Polito, V., Hansteen, V., et al., Sol. Phys., 296, 84(2021)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2016A%26A...593A..32G/abstract\">Grubecka, M., Schmieder, B., Berlicki, A., et al., A&A, 593, A32(2016)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2020A%26A...639A..22J/abstract\">Joshi, R., Chandra, R., Schmieder, B., et al., A&A, 639, A22(2020a)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2020A%26A...642A.169J/abstract\">Joshi, R., Schmieder, B., Aulanier, G., Bommier, V., Chandra, R., A&A, 642, A169(2020b)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2021A%26A...645A..80J/abstract\">Joshi, R., Schmieder, B., Tei, A., et al., A&A, 645, A80(2021)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2015ApJ...810...38K/abstract\">Kim, Y.-H., Yurchyshyn, V., Bong, S.-C., et al., ApJ, 810, 38(2015)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2014Sci...346C.315P/abstract\">Peter, H., Tian, H., Curdt, W., et al., Science, 346, 1255726(2014)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2019ApJ...883...52R/abstract\">Ruan, G., Schmieder, B., Masson, S., et al., ApJ, 883, 52(2019)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2017ApJ...851...67S/abstract\">Shen, Y., Liu, Y. D., Su, J., Qu, Z., & Tian, Z., ApJ, 851, 67(2017)</a>","<a href=\"https://ui.adsabs.harvard.edu/abs/2018SSRv..214..120Y/abstract\">Young, P. R., Tian, H., Peter, H., et al., Space Sci. Rev., 214, 120(2018)</a>"],"pubDate":"2021-06-10T18:49:18.957Z"}