The formation heights of CME-driven shocks using empirical Alfvén maps of the solar corona

The formation heights of CME-driven The formation heights of CME-driven shocks using empirical Alfvén maps of the shocks using empirical Alfvén maps of the

solar coronasolar corona

Pietro Zucca, Eoin Carley, Shaun Bloomfield, Peter

Gallagher

Trinity College Dublin

School of Physics, Trinity College Dublin, Ireland

OverviewOverview

• Shocks in the solar corona and their radio signature

• Density and Alfvén speed of the solar corona

• Study of 2011 September 22 Type II radio burst

• Results and conclusions

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Type II radio burstType II radio burstPlasma Emission Shock Condition

Rosse Solar Terrestrial Observatory (RSTO; Zucca et al. 2012)

(ne,t) (r,t)ne(r) model

From density to heightFrom density to height

2 orders of magnitude

Alfvén Speed Alfvén Speed

Mann et al. 2002

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Alfvén Speed 2D Alfvén Speed 2D ModelModel

Warmuth et al. (2005)

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Density Map with SDO/AIA and Density Map with SDO/AIA and SOHO/LASCOSOHO/LASCO

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B-Field with PSFFB-Field with PSFF

Emission MeasureEmission Measure

Aschwanden et al. (2011)

1918 20 21 22 23

Emission Measure to Emission Measure to DensityDensity

Menzel (1936)

The density can be estimated if we know the LOS length S(x,y)

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Density with Density with SOHO/LASCOSOHO/LASCO

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Hayes et al. (2001)

Plane Parallel Solution

Combined Model

Density ModelsDensity Models

Spherical Symmetric Solution

SDO/AIA data

SOHO/LASCO data

Polar density MapPolar density Map

SDO/AIA 1-1.3 R

SOHO/LASCO 2.5-6 R

Model 1.3 - 2.5 R

Electron Density [cm-3]zuccap@tcd.ie

Density / Position Density / Position AngleAngle

Electron Density MapElectron Density Map

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SDO

MODEL

LASCO

1.3 R

2.5 R

Magnetic FieldMagnetic Field0.50.1 2.5 15 90 500

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Magnetic field [Gauss]

Alfvén Speed MapAlfvén Speed Map

2 RSun

150 300 600 1250 2500 5000

zuccap@tcd.ieZucca et al. 2013, A&A in prep

Study of 2011 Sep 22 Type II radio burstStudy of 2011 Sep 22 Type II radio burst

Using the 2D density and Alfvén maps

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CME eruptionCME eruption

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Non-radial Non-radial kinematicskinematics

EUV Height time

Type II Height Time

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Height-time Height-time comparisoncomparison

EUV propagating feature Type II radio burst

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Matching KinematicsMatching Kinematics

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90-70 MHz

Matching KinematicsMatching Kinematics

150 MHz

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Matching KinematicsMatching Kinematics

150 MHz

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150 MHz from NRH

Alfven SpeedAlfven Speed

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Matching KinematicsMatching Kinematics

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90-70 MHz

ConclusionsConclusions

• 2D density and Alfvén maps

• Non-radial study of Type II burst – CME

• Shock formed in the ‘Upper-flank’ region

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