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On mass evolution of CMEs

Li Feng , Bernd Inhester , Yuming Wang , Fang Shen , Chenglong Shen , Weiqun Gan. On mass evolution of CMEs. 1. Max Planck Institute for Solar System Research, Germany 2. Purple Mountain Observatory, China 3. University of Technology and Science , China

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On mass evolution of CMEs

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  1. LiFeng,BerndInhester,YumingWang, FangShen,ChenglongShen,WeiqunGan OnmassevolutionofCMEs 1.MaxPlanckInstituteforSolarSystemResearch,Germany 2.PurpleMountainObservatory,China 3.UniversityofTechnologyandScience,China 4.Nationalspacesciencecenter, China ESMP-14Dublin

  2. Outline Massevolution in coronagraph images Trytoanswertwo questions: 1.Why the mass of a CME increases with time, physically does it come from the convected mass fromthelowercoronain the dimming region or the piled-up massofsolar wind? 2. When the mass is convected from the lower corona to the coronagraph FOV, how the flow speed is distributed in a CME? Conclusionandoutlook

  3. Mass calculationfromcoronagraphimages Thomson scattering b/bs:brightnessinunitsofMSB σ:differentialThomsonscatteringcrosssection μ:limbdarkeningcoefficient χ:scatteringangle A,B,C,D:knownfunctionsofthedistanceofthescatteringlocation χ base-difference image COR1+2BLASCOC2COR1+2A CME propagation GCSforwardmodeling Columndensity+pixelsize +He：H=1：10 massineachpixel

  4. Mass images Mass_B:totalmassfromCORB Mass_A: totalmass from CORA

  5. Mass evolution: why does the apparent mass increase? Mass=0.5*(mass_A+mass_B) • Massincreasedueto: • 1.occultereffect：moremassenterstheFOVofcoronagraph? • solarwindplasmapiledupinfrontofaCME? • continuousoutflowfromthelowcoronainthedimmingregion? • Atwhatheightthethreepossibilitiesaredominated,respectively?

  6. Where does the geometricalocculter effect dominated? atlowerheight Truemassevolutionmodelwithoutanocculter:m(h)=m0+Δm(h-hocc) Apparentmassevolutionwithanocculterforaconic-coneCME Red: true evolution Green: apparent evolution Freeparameters: hocc:theheightofaneffectiveocculteredge m0:amodeledinitialmassbelowtheocculteredge Δm:massincreasepersolarradius Beinetal., 2013

  7. Piled-up solar wind mass: snow-plough model Tappinetal.(2006) ρSW(r)andvSW(r)aroundtheCME: 3DMHDsimulation:global3Dsolarwinddistribution(Shenetal.,JGR,2007,2013) Acme=Wface*Wedge*hfront2 distance(Rs)

  8. Compare theevolutionofthe measured mass and the piled-up mass for CME of various speeds:dm/dt measurement model CMEspeed(km/s) 1.dm/dtfromsnowploughmodelislowerandflatter 2.Discrepancybetweenthemeasuredandmodeleddm/dtdecreaseswithtime 3.Piled-upsolarwindmassM_pile:M_pile/M_15Rs=30% 4.Anupperlimit 5.ResultsforeightCMEswithdifferentspeeds:M_pile/M_15Rs=10%~33%

  9. Convected mass from the dimming region Mass=densitydepletion * dimmingarea * dimmingdepth* mi before Dopplervelocity （Tianetal.,2012) after difference 30417119321133594131 CME on 2011-06-21

  10. massloss from the dimming region Mass=densitydepletion(ΔN)* dimmingarea(S) * dimmingdepth(L) * mi Tianetal.(2012) coronagraph DEManalyses(chengetal.2012) dimming 1.Massfromdimming:from40%to50%. 2.Lowerlimit:transitionregionoutflowsrefillthecoronaldimmings S=sumofpixelswhoseEMislessthan85%ofEMbeforetheeruption L=sqrt(S) N=sqrt(EM/L)

  11. Why does the apparent massincrease? • Thegeometricaloccultereffectplaysitsroleatheightbelow7~8Rs. • Thesolarwindpileupcancontributeupto10%~33%ofthemassincoronagraphimages • Themasslossinthedimmingregionisatleast40%~50%ofthemassincoronagraphimagesfortheCMEon2011-06-21. Ifthemassincreasemostlycomesfromthedimmingregion,howisthemassconvectedfromthelowercoronaaccrosstheFOVofcoronagraph? SpeeddistributioninaslowCME(v<500km/s)

  12. SpeeddistributionwithinaCME Undertheassumptionthat the CMEmassall comesfromthelowercorona rend ri m(ri,tj) Themasschangewithtimeinshellsfromritorendisduetothemassflowatr=ri

  13. speed distributionofeachshell v(r,tj)increaseswithdistanceanditdoesnotfollowalinearpattern.

  14. time evolution of thespeedina shell v(ri,t)decreaseswithtime

  15. Locations of theleading edge and theLagrangiantrajectories Lagrangiantrajectoriesofdifferentshells Subjectiveleadingedgepositions

  16. Conclusions • When a CME is within the COR FOV, most of its mass come from the dimming regionandthesolarwindpileuphaslesscontribution. • We derived the speed distribution of each shell in a slowCME,anditincreaseswithdistanceanddecreaseswithtime.

  17. backupslides

  18. Validate the speed distribution:comparingthemeasuredmassprofilestothepredictedprofilesfromV(r,tj) Lax-wendroffschemeisusedtocalculatethemassprofilem(r,ti+1)ingreen fromthemeasuredm(r,ti)inwhite. Orange:measuredm(r,ti+1)

  19. Error analyses ICME: Image noise, pre-CME image subtraction Cplasma: in an average CME, the majority of the plasma is fully ionized He composition: 6%~10% Ce: convert brightness to mass in a pixel according to the Thomson Scattering Propagation direction CME width Regiondefinition Region of interesting /Sector definition

  20. 3DMHDsimulation:global3Dsolarwinddistribution (Shenetal.,JGR,2007,2013) B:Potentialfieldextrapolatedfromphotosphericsynopticmap V：Parker’ssolarwindsolution T:adiabaticprocess N:momentumconservation

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