Two strong white-light solar flares in AR NOAA 12673 as potential clues for stellar superflares

Abstract

Recently, two strong homologous white light flares of X-GOES class occurred on the Sun on Sept. 06, 2017, providing a rare exceptional opportunity to study the mechanisms responsible for the formation of the magnetic field configurations suitable for the manifestation of such yet enigmatic eruptive events and their effects in the lower layers of the solar atmosphere. Using photospheric vector magnetograms, taken before the beginning of the two X-class events, as boundary conditions to reconstruct the non$-$linear coronal magnetic field configuration, we identified two related 3D null points located at low heights above the photosphere (i.e. in very low corona). These null points are most likely responsible for the triggering of the two strong X-GOES class flares. We deduced that their formation at such low altitudes may plausibly be ascribed to the peculiar photospheric horizontal motions of the main magnetic structures of the hosting Active Region NOAA 12673. These events can be adopted as a hint for a possible interpretation of the activity of young G-type stars, recently reported by the Kepler mission. We argued that a possible explanation of the acceleration of huge numbers of particles producing white light emission, during the Sept. 6 events as well as during white light flares in young Sun-like stars, might be attributed to the special accompanying conditions of the occurrence of magnetic reconnection at low altitudes of their atmospheres.

arXiv commentAccepted for publication in Solar Physics Journal; 18 pages, 9 figures. This is a post-peer-review, pre-copyedit version of the accepted article

References in corpus (18)

• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Superflares on Solar Type Stars Observed with Kepler I. Statistical Properties of Superflares
• Tracking Vector Magnetograms with the Magnetic Induction Equation
• The standard flare model in three dimensions. II. Upper limit on solar flare energy
• Superflares on Solar-Type Stars Observed with Kepler II. Photometric Variability of Superflare-Generating Stars : A Signature of Stellar Rotation and Starspots
• 3D Null Point Reconnection Regimes
• Successive X-class flares and coronal mass ejections driven by shearing motion and sunspot rotation in active region NOAA 12673
• An Extreme Solar Event of 20 January 2005: Properties of the Flare and the Origin of Energetic Particles
• Do all Flares have White Light Emission?
• Formation and Eruption of an Active Region Sigmoid: I. Study by Nonlinear Force-Free Field Modeling
• Block-induced complex structures building the flare-productive solar active region 12673
• Heating mechanisms in the low solar atmosphere through magnetic reconnection in current sheets
• On the origin of two X-class flares in active region NOAA 12673 - Shear flows and head-on collision of new and pre-existing flux
• Kinetic modeling of particle acceleration in a solar null point reconnection region
• Steady state reconnection at a single 3D magnetic null point
• Homologous white light solar flares driven by photosperic shear motions
• The Origin of Superflares on G-Type Dwarf Stars of Various Ages
• Evolution of twist-shear and dip-shear during X-class flare of 13 December 2006: Hinode observations

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• Non-LTE inversions of a confined X2.2 flare: I. Vector magnetic field in the photosphere and chromosphere
• Eruptive-Impulsive Homologous M-class Flares Associated with Double-Decker Flux Rope Configuration in Mini-Sigmoid of NOAA 12673
• Can Sub-photospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?
• An MHD Modeling of Successive X2.2 and X9.3 Solar Flares of 2017 September 6
• Plausibility of ultraviolet burst generation in the low solar chromosphere
• Clustering of fast Coronal Mass Ejections during the solar cycles 23 and 24 and implications for CME-CME interactions
• Spectral diagnostics of cool flare loops observed by SST: I. Inversion of the Ca II 8542 Å and H$\beta$ lines
• On the evolution of a sub-C class flare: a showcase for the capabilities of the revamped Catania Solar Telescope
• The magnetic field environment of active region 12673 that produced the energetic particle events of September 2017
• Rapid Evolution of Bald Patches in a Major Solar Eruption
• Comparative case study of two methods to assess the eruptive potential of selected active regions