Kyoung-Sun Lee1(ksun.lee@nao.ac.jp), Kyoko Watanabe2, Hirohisa Hara1, David Brooks3, Shinsuke Imada4 1Solar Science Observatory, National Astronomical Observatory of Japan, Japan

2Department of Earth and Ocean Sciences, National Defense Academy of Japan, Japan 3 George Mason University, USA

4 Solar-Terrestrial Environment Laboratory, Nagoya University, Japan

Abstract

I. Introduction

II. Observations

Whenaareoccurs,wecanobservesolarplasmaresponseinmul4-wavelengthsfromop4caltoHXR.Especially,somestrongaresproducewhitelightemissions,whitelight(WL)flares,andareribbonsareobservedinthelowatmosphere.Tounderstandhowtheenergytransportstothelowatmosphereandhowthelowatmosphereresponsestothesolarflares,weinves4gatedtheUVandEUVspectrallinesandWLcon4nuumimagessta4s4cally.Wehaveinves4gatedtheMgIItriplet,SiIVemissionandWLcon4nuumin60MandXclassflares,whichdetectedbytheIRIS,SDO/HMIandHinode/SOTfrom2014to2016.Fromtheanalysis,wehavefoundthattheMgIItripletmostlybecomesemissionduringflaresalongtheareribbonsandfootpointsoftheflaringloopregion,whichindicatesthatthelowatmospherichea4ng.Atthesame4me,wealsoexaminedtheDopplervelocityoftheSiIVemission,andmostlytheyshowthered-shiUedemission(40kms-1)correlatedin4meandloca4onoftheMgIItripletemission.WLcon4nuumalsoenhancedduringseveralflares(17flares),butnotinalltheflares.BycomparisonbetweentheMgIItripletandWLcon4nuum,wealsodiscusstheenergytransportprocess,suchasthermalconduc4on,electronbeam,orAlfvnwave,intheareswith/withoutWLflares.

I.1 White light flare

II.1 IRIS flare list II.2 Sample event

III.1 Correlations

FeXIV

FeXXIV

B C D

Statistical investigation of low atmospheric response during flares using the multi-wavelengths observations by IRIS, Hinode, and SDO

III. Results III.2 Three different types of events

I.3 Low atmospheric heating signature

•  Spatial correlations

•  Standardflaremodel

•  Strongflaresproducewhitelightcon4nuum,Whitelightflare(WLF).•  HXR–WLFcorrela4onsuggeststhatflare-ecceleratedelectronsare

involvedintheproduc4onoftheWLemission•  Itiss4llunclearhowtheenergyistransportedtothelowatmosphere

andproducestheWLFs

(Pereiraetal.2015)

•  MgIItripletemissionappearsalongflareribbons

•  Significantou^low(Dopplervelocity)inFeXXIobservedatnearthefootpointsofflaringloop,notalltheflareribbon.

•  WLflarekernelloca4ons:combina4onofMgIIemi`ngregion&FeXXIou^lowingregion

•  WithWLFs:Temporalcorrela4onswithHXRpeaksandMgIItripletemissionpeaks•  Strongflarecases–con4nuumenhancementsuppressesthera4ovalue

•  WithoutWLFs:MgIItripletemissionpeaksareobservedaUertheHXRpeaksortheSXRpeaks

•  MgIItripletemission:IfflareribbonfootpointsaredetectedtotheIRISslit,MgIItripletemissionsareobserved.

•  WLFs(13/47,~28%):NotalltheeventsproduceWLFs.IftheHXRpeakintensityvalueislessthan1,WLFswerenotobserved.

I.2 Energy transport process

•  Needtochecktemporalevolu4onofthelowatmosphericresponsewithHXRemission

•  M2.9flarewithWLF

•  Fe XXI, Si IV doppler velocity variations are correlated with Mg II emission region in location and time

FeXXI

SiIV

MgIItripletemission

Dopplervelocity

Whitelightflare

IRIS-9, Gottingen, 25-29 June 2018

Poster

4. Eruptions in the solar atmosphere

Statistical investigation of low atmospheric response during flaresusing the multi-wavelengths observations by IRIS, Hinode, and SDO

Kyoung-Sun Lee1, Kyoko Watanabe2, Hirohisa Hara1, David Brooks3, Shinsuke Imada4

1National Astronomical Observatory of Japan2National Defense Academy of Japan

3George Mason University4Nagoya University

When a flare occurs, we can observe solar plasma response in multi-wavelengths from optical to HXR.Especially, some strong flares produce white light emissions, white light (WL) flares, and flare ribbonsare observed in the low atmosphere. To understand how the energy transports to the low atmosphereand how the low atmosphere responses to the solar flares, we investigated the UV and EUV spectrallines and WL continuum images statistically. We have investigated the Mg II triplet, Si IV emission andWL continuum in 60 M and X class flares, which detected by the IRIS, SDO/HMI and Hinode/SOTfrom 2014 to 2016. From the analysis, we have found that the Mg II triplet mostly becomes emissionduring flares along the flare ribbons and footpoints of the flaring loop region, which indicates thatthe low atmospheric heating. At the same time, we also examined the Doppler velocity of the Si IVemission, and mostly they show the red-shifted emission (⇠40 km s�1) correlated in time and locationof the Mg II triplet emission. WL continuum also enhanced during several flares (17 flares), but not inall the flares. By comparison between the Mg II triplet and WL continuum, we also discuss the energytransport process, such as thermal conduction, electron beam, or Alfvn wave, in the flares with/withoutWL flares.

92