MHD modeling and diagnostics of coronal...

MHD modeling and diagnostics of coronal plasma

Fabio Reale Dipartimento di Fisica e Chimica Universita` di Palermo fabio.reale@unipa.it

3rd METIS Science and Technical Meeting Napoli, 15-17 October 2013

Outline

!  The subject: fallbacks of coronal eruptions

!  The tools: MHD modeling

Bright hot impacts by erupted fragments falling back on the Sun: a template for stellar accretion

Fabio Reale (Univ. Palermo) Salvatore Orlando (INAF-OAPa) Paola Testa (Harvard CfA, USA) Giovanni Peres (Univ. Palermo) Enrico Landi (Univ. Michigan, USA) Carolus (Karel) J. Schrijver (LMSAL, USA)

Accretion flows on young stars (T Tauri)

Motivation: Accretion in YSO

!  Disk-star: magnetic funnels (Königl 1991)

!  Accretion flows: V≫100 km/s !  Impact: IR/V/UV excess (Bertout et al.

1988, Natta et al. 2006, Herczeg & Hillenbrand 2008, Donati et al. 2008)

!  +Soft X-ray excess: dense (1011 −

1013 cm−3) and hot (2-4 MK) plasma (Kastner et al. 2002, Telleschi et al. 2007, Argiroffi et al. 2007)

Fendt 1995

Accretion impacts

!  Questions: ! Accretion rate: UV/V/NIR ≫ X. Why? ! What is the role of absorption? ! What is the role of stream structuring?

!  Concept: use the Sun as a template

The flare and the eruption: 7 June 2011

K. Schrijver

The impacts region

-1000 -500 0 500 1000[arcsec]

-1000

-500

0

500

1000

[arc

sec]

-1000 -500 0 500 1000

-1000

-500

0

500

1000

08:00 UT - 171 A F. Reale P. Testa

Close up: 171 A (Fe IX, logT~5.9)

F. Reale

Data analysis

!  Impacting plasma: !  Density: 2 < n < 10 x 1010 cm-3 (from

absorption) !  Velocity: 300 < v < 450 km/s (from images

and STEREO data) !  Size: r~2000-4000 km, l~2000-10000 km

!  Weak magnetic field (β≫1, HMI)

!  Free fall (STEREO)

Landi & Reale, 2013, ApJ, in press

E. Landi

P. Testa

K. Schrijver

P. Testa

Hydrodynamic simulations

!  Hydrodynamic model of plasma blobs downfalling in a low-density (108 cm−3) corona !  Impact speed: 400 km/s ! Density: 5 × 1010 cm−3

!  2D cylindrical geometry !  Spatial resolution: 5 km !  Radius: 2000 km !  FLASH code (Fryxell et al. 2000)

S. Orlando, F. Reale, G. Peres

Train of droplets

Density Temperature

S. Orlando

Train of droplets: emission

!  Emitting plasma: 7%

Cross-section Integrated S. Orlando

We match the observation….

0 20 40 60 80 100 120

0

20

40

60

80

100

120

[arc

sec]

0 20 40 60 80 100 1200

20

40

60

80

100

120

0100200300400500600700

20 40 60 80 100 120

20 40 60 80 100 120

20 40 60 80 100 120

20 40 60 80 100 120

Time = 136 sec

6.90

6.95

7.00

7.05

7.10

7.15

z [1

010 c

m]

-9-8-7-6-5-4-3

0.0000.005

0.010

0.0150.020

Time = 116 sec

-9-8-7-6-5-4-3

0.0000.005

0.010

0.0150.020

Time = 140 sec

-9-8-7-6-5-4-3

0.0000.005

0.010

0.0150.020

-10 0 10x [108 cm]

6.90

6.95

7.00

7.05

7.10

7.15

z [1

010 c

m]

810

12

1416

4.04.55.05.56.06.5

-10 0 10x [108 cm]

810

12

1416

4.04.55.05.56.06.5

-10 0 10x [108 cm]

810

12

1416

4.04.55.05.56.06.5

Quantitative agreement: Light curves

1300 1400 1500 1600 1700 1800Time [s]

0

500

1000

1500

Flux

[DN

/s/p

ix]

Model Data

1500 1600 1700 1800 1900 2000Time [s]

0

500

1000

1500

Flux

[DN

/s/p

ix]

0 100 200 300 400 500 600Time [s]

0

500

1000

1500

Flux

[DN

/s/p

ix]

low density 250 km/s

0 100 200 300 400 500 600Time [s]

0

1000

2000

3000

Flux

[DN

/s/p

ix]

F. Reale S. Orlando

0 100 200 300 400 500 600Time [s]

0

500

1000

1500

Flux

[DN

/s/p

ix]

4100 4200 4300 4400 4500 4600Time [s]

0

1000

2000

3000

Flux

[DN

/s/p

ix]

Hints/results stars vs Sun

!  Density: 1011−1013 cm−3

!  Velocity: 400-500 km/s

!  Temperature: 2 – 4 MK !  Accretion rate: 10-12- 10-7

M"/yr

!  ?

!  Density: 5 1010 cm−3

!  Velocity: 300-450 km/s

!  Temperature: ~1 MK !  Accretion rate: 10-14 M"/yr

!  Absorption -> Emitting mass: 5-25%

!  Emission from disk material

!  Role of fragmentation

Stars Sun

The tools: 3D MHD modeling of the heating of a twisted coronal loop

F. Reale – UniPa S. Orlando – INAF/OAPa M. Guarrasi – CINECA A. Mignone – UniTo G. Peres - UniPa

The 3D MHD model

Three-dimensional cylindrical coordinates

HPC PRACE project

(PRACE n°2011050755) The way to heating the solar corona: finely-resolved twisting of magnetic loops

PI: F. Reale Co-I: S. Orlando, M. Miceli, M. Guarrasi

Simulations: 3D MHD (resistivity; thermal cond.; radiative cooling; gravity)

Numerical code: PLUTO 4 (Mignone et al. 2007)

Resources: ~ 31 Mhours on BlueGene/P FERMI/CINECA (storage ~ 10 TB)

Project schedule: October 2012/April 2013

Twisting, reconnection and coronal heating [ MK ]

Last 10 min Thermal conduction along magnetic field lines

The corona heats to ~ 3 MK

Temperature

Inflows observed with coronagraphs

UV emission: He II

Perspectives

!  Next step: Magnetic channelling of inflows

!  Modeling: 3D MHD

!  Observations: coordinated METIS+SPICE+EUI+ SDO/AIA