Continuum enhancements, line profiles and magnetic field evolution during consecutive flares

Abstract

During solar flares, magnetic energy can be converted into electromagnetic radiation from radio waves to $\gamma$ rays. Enhancements in the continuum at visible wavelengths give rise to white-light flares, as well as continuum enhancements in the FUV and NUV passbands. In addition, the strong energy release in these events can lead to the rearrangement of the magnetic field at the photospheric level, causing morphological changes in large and stable magnetic structures like sunspots. In this context, we describe observations acquired by satellite instruments (IRIS, SDO/HMI, Hinode/SOT) and ground-based telescopes (ROSA/DST) during two consecutive C7.0 and X1.6 flares occurred in active region NOAA 12205 on 2014 November 7. The flare was accompanied by an eruption. The results of the analysis show the presence of continuum enhancements during the evolution of the events, observed both in ROSA images and in \textit{IRIS} spectra. In the latter, a prominent blue-shifted component is observed at the onset of the eruption. We investigate the role played by the evolution of the $\delta$ sunspots of the active region in the flare triggering, and finally we discuss the changes in the penumbrae surrounding these sunspots as a further consequence of these flares.

arXiv comment19 pages, accepted for ApJ; some figures are in B/W to accomplish size limits

References in corpus (45)

• The Interface Region Imaging Spectrograph (IRIS)
• The Solar Optical Telescope for the Hinode Mission: An Overview
• An Observational Overview of Solar Flares
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• Flare-productive active regions
• The standard flare model in three dimensions III. Slip-running reconnection properties
• The standard flare model in three dimensions. II. Upper limit on solar flare energy
• Numerical sunspot models: Robustness of photospheric velocity and magnetic field structure
• Response of the Photospheric Magnetic Field to the X2.2 Flare on 2011 February 15
• Temporal evolution of multiple evaporating ribbon sources in a solar flare
• Slipping magnetic reconnection during an X-class solar flare observed by SDO/AIA
• Observational Evidence of Back-reaction on the Solar Surface Associated with Coronal Magnetic Restructuring in Solar Eruptions
• Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar Flare
• High-resolution observations of flare precursors in the low solar atmosphere
• ROSA: a high cadence, synchronized multi-camera solar imaging system
• Do all Flares have White Light Emission?
• Abrupt longitudinal magnetic field changes in flaring active regions
• Abrupt changes in photospheric magnetic and Lorentz-force vectors during neutral-line flares
• A spatio-temporal description of the abrupt changes in the photospheric magnetic and Lorentz-force vectors during the 2011 February 15 X2.2 flare
• 3D magnetic reconnection and its application to solar flares
• IRIS Observations of the Mg II h & k Lines During a Solar Flare
• The fast filament eruption leading to the X-flare on March 29, 2014
• The Relationship between the Sudden Change of the Lorentz Force and the Magnitude of Associated Flares
• Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares
• Blue wing enhancement of the chromospheric Mg II h and k lines in a solar flare
• Precursor of Sunspot Penumbral Formation discovered with Hinode SOT Observations
• Sudden Photospheric Motion and Sunspot Rotation Associated with the X2.2 Flare on 2011 February 15
• Tether-cutting Reconnection between Two Solar Filaments Triggering Outflows and a Coronal Mass Ejection
• Formation of the penumbra and start of the Evershed flow
• A Statistical Study of Photospheric Magnetic Field Changes During 75 Solar Flares
• A distinct magnetic property of the inner penumbral boundary. II. Formation of a penumbra at the expense of a pore
• On the formation of a stable penumbra in a region of flux emergence in the Sun
• Magnetic braids in eruptions of a spiral structure in the solar atmosphere
• Transient Magnetic and Doppler Features Related to the White-light Flares in NOAA 10486
• Slipping magnetic reconnections with multiple flare ribbons during an X-class solar flare
• Observational Evidence of a Flux Rope within a Sunspot Umbra
• Flare reconnection-driven magnetic field and Lorentz force variations at the Sun's surface
• Observation of a 3D magnetic null point
• Slipping reconnection in a solar flare observed in high resolution with the GREGOR solar telescope
• On the relationship between sunspot structure and magnetic field changes associated with solar flares
• Properties of the Umbral Filament Observed in Active Region NOAA 12529
• The pre-penumbral magnetic canopy in the solar atmosphere
• A Statistical Study of the Magnetic Imprints of X-Class Solar Flares

Cited by in corpus (5)

• The Statistical Relationship between White-light Emission and Photospheric Magnetic Field Changes in Flares
• High-resolution Observations of a C9.3 White-light Flare and Its Impact on the Solar Photosphere
• Confinedness of an X3.1 class solar flare occurred in NOAA 12192: Analysis from multi-instruments observations
• A new view of the solar interface region from the Interface Region Imaging Spectrograph (IRIS)
• Statistical Study of Balmer Continuum Enhancement in Solar Flares