Capability of a scenario to drive a Moreton wave

Mariana C´ecere

Collaborators: A. Costa, G. Krause, C. Francile, E. Zurbriggen, S. Elaskar Institute of Theoretical and Experimental Astronomy – Astronomical Observatory of C´ordoba– National University of C´ordoba– Argentina [email protected] December 10, 2020

MHD Coronal Seismology 2020

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 1 / 18 Observations Characteristics Moreton wave observations

Characteristics: chromospheric wave observed in Hα, distance traveled ∼ 500 Mm (R = 695,7 Mm), radial velocities ∼ (500 − 2000) km/s → driver must be of coronal origin

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 2 / 18 Observations Controversy Controversy

The global large–amplitude coronal perturbations and shock waves are produced by:

Flares: Explosive and powerful CMEs: An upward movement of the energy release (blast wave) flux rope () + a 3D expansion ()

* Since CMEs and flares can be jointly observed, it is difficult to identify which phenomenon produces the Moreton wave. * Not every CME or flare produces a Moreton wave. Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 3 / 18 Observations December 6, 2006 event December 6, 2006 event

Francile et al, 2013: X 6,5 flare in the NOAA AR10930

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 4 / 18 Observations December 6, 2006 event December 6, 2006 event

Francile et al, 2013: vMor ∼ 700 km/s; tappar ∼ 100 s; dappar ∼ 100 Mm

They conclude that the MW is produced by a coronal fast-shock wave of a “blast” type (a flare) originated in a single source during a CME.

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 5 / 18 Observations December 6, 2006 event March 29, 2014 event

Francile et al, 2016: X 1,0 flare in the AR12017

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 6 / 18 Observations March 29, 2014 event March 29, 2014 event

Francile et al, 2016: vMor ∼ (500 − 900) km/s; dappar ∼ 50 Mm

They conclude that the driver is a 3D piston that can be attributed to the front of the CME, expanding at the speed of the associated rising filament.

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 7 / 18 Simulations CMEs expansion Model: CME expansion

FLASH code (Fryxell et al. 2000): ideal MHD equations.

* Flux-rope temperatures: (0,1; 1; 10)MK. Equilibrium between FR and outside (heavier → lighter FRs). IC is not in equilibrium. * Background magnetic field: (1 − 10)G.

Krause, C´ecere, Zurbriggen, Costa, Francile and Elaskar, MNRAS 2018

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 8 / 18 Simulations CMEs expansion Magnetic Model

Forbes, 1990: Catastrophe model for CMEs

j0 current density r FR’s radius d depth of the line dipole ∆ thickness of the transition layer

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 9 / 18 Simulations CMEs expansion Evolution of the plasma density

−2 Evolution of the plasma density for j0 = 1000 statA cm , TFR = 10 MK

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 10 / 18 Simulations CMEs expansion Shock waves: sweeping the

A circular shaped shock that travels in the corona and sweeps the chromosphere

Left) Plasma density. Right) Chromospheric distance vs time (Courtesy C. Francile).

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 11 / 18 Simulations CMEs expansion Shock wave features

The coronal shock is ahead of the chromospheric perturbation

Density profiles in the solar atmosphere for t = 150s and B0 = 13G. Left) corona; Middle) chromosphere Right) Distance vs. time of various features: the fastest front detected with AIA 193 A˚ (white line), the Moreton wavefront recorded by HASTA (yellow line), and the wavefront detected by AIA 304 A˚ (red line) (Francile et al., 2016).

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 12 / 18 Simulations CMEs expansion

Flux-rope velocities vs j0

To hottest temperature case, an increase of j0 implies a significant increase of the speed (> 200km/s), but for the colder temperature cases, the speed remains almost constant

Filled: with fast ms shock Unfilled: without fast ms shock

FR velocities obtained at t = 180s.

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 13 / 18 Simulations CMEs expansion

Coronal wave front velocities vs j0

Note that the highest coronal shock speed (similar to the required Moreton wave speed) are only obtained for the hottest (lightest) flux rope configuration

Filled: with fast ms shock Unfilled: without fast ms shock

Coronal wave velocities obtained at t = 180s.

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 14 / 18 Simulations CMEs expansion

Chromospheric compression density ratio vs j0

The cases that have coronal shock waves lead a Moreton wave. Therefore, in this CME scenario a fast magnetosonic shock wave would be a necessary requirement to produce a detectable Moreton wave

Filled: with fast ms shock Unfilled: without fast ms shock

Chromospheric compression density ratio obtained at t = 180s.

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 15 / 18 Simulations CMEs expansion December 6, 2006 event

Sensitivity study: fix h0 and d

The delay of the space–time location in the numerical results with respect to the observational data could be adjusted modifying the initial altitude h0 of the FR and the dipole depth d, for each of the particular combinations of FR temperatures and j0 values.

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 16 / 18 Conclusions Krause et al, 2018 Conclusions: CME expansion

The CME dynamics is determined by the magnetic field strength and the flux rope weight Hot and light flux ropes and large magnetic fields are able to provoke the CME lift-off and significant expansion to produce an intense fast magnetosonic shock leading to a high-speed Moreton wave. The scarcity of Moreton waves –in comparison with the large number of CME events– could be explained by: 1 Only 32 % of the CMEs with associated flux ropes are of the hot type (with temperatures larger than 7 MK) (Aparna & Tripathi 2016). 2 Also, ∼ 1 % CMEs are shock drivers (Gopalswamy 2006).

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 17 / 18 Conclusions Krause et al, 2018

Thanks!

Mariana C´ecere (IATE-OAC) Moreton waves MHD Coronal Seismology 2020 18 / 18