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MHD modeling and diagnostics of coronal plasma
Fabio Reale Dipartimento di Fisica e Chimica Universita` di Palermo [email protected]
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]
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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….
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0100200300400500600700
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Time = 136 sec
6.90
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z [1
010 c
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-9-8-7-6-5-4-3
0.0000.005
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0.0150.020
Time = 116 sec
-9-8-7-6-5-4-3
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Time = 140 sec
-9-8-7-6-5-4-3
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-10 0 10x [108 cm]
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4.04.55.05.56.06.5
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-10 0 10x [108 cm]
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4.04.55.05.56.06.5
Quantitative agreement: Light curves
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Model Data
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low density 250 km/s
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F. Reale S. Orlando
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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
