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Bombs and Flares at the Surface and Lower Atmosphere of the Sun
Leenaarts, J.; Hansteen, V. H.; Rouppe van der Voort, L. +3 more
A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the Hα line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging Spectrograph have revealed another type of plasma “bombs” (UV bursts) with high temperatures of perhaps up to 8 × 104 K wit…
The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29
Kowalski, Adam F.; Daw, Adrian; Carlsson, Mats +2 more
The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Re…
Intermittent Reconnection and Plasmoids in UV Bursts in the Low Solar Atmosphere
De Pontieu, B.; Martínez-Sykora, J.; Hansteen, V. H. +9 more
Magnetic reconnection is thought to drive a wide variety of dynamic phenomena in the solar atmosphere. Yet, the detailed physical mechanisms driving reconnection are difficult to discern in the remote sensing observations that are used to study the solar atmosphere. In this Letter, we exploit the high-resolution instruments Interface Region Imagin…
Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
Martínez-Sykora, Juan; De Pontieu, Bart; Nóbrega-Siverio, Daniel +3 more
We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion-neutral interaction effects using the generalized Ohm’s law, I.e., we include the Hall term and the ambipolar diffusion (Pe…
Solar Active Region Coronal Jets. II. Triggering and Evolution of Violent Jets
Panesar, Navdeep K.; Moore, Ronald L.; Sterling, Alphonse C. +2 more
We study a series of X-ray-bright, rapidly evolving active region coronal jets outside the leading sunspot of AR 12259, using Hinode/X-ray telescope, Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI), and Interface Region Imaging Spectrograph (IRIS) data. The detailed evolution of such r…
Surges and Si IV Bursts in the Solar Atmosphere: Understanding IRIS and SST Observations through RMHD Experiments
Martínez-Sykora, J.; Rouppe van der Voort, L.; Moreno-Insertis, F. +1 more
Surges often appear as a result of the emergence of magnetized plasma from the solar interior. Traditionally, they are observed in chromospheric lines such as Hα 6563 \mathringA and Ca II 8542 \mathringA . However, whether there is a response to the surge appearance and evolution in the Si IV lines or, in fact, in many other transition region line…
A Parameter Study for Modeling Mg II h and k Emission during Solar Flares
Kleint, Lucia; Rubio da Costa, Fatima
Solar flares show highly unusual spectra in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral profiles of the Mg II h and k lines. We aim to understand the formation of the chromospheric and optically thick…
Observations and Numerical Models of Solar Coronal Heating Associated with Spicules
De Pontieu, B.; McIntosh, S. W.; De Moortel, I. +1 more
Spicules have been proposed as significant contributors to the mass and energy balance of the corona. While previous observations have provided a glimpse of short-lived transient brightenings in the corona that are associated with spicules, these observations have been contested and are the subject of a vigorous debate both on the modeling and the…
What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?
Martínez-Sykora, Juan; De Pontieu, Bart; Chintzoglou, Georgios
Spicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed the presence of very high apparent motions of order 100-300 km s-1 in spicules, as measured in the plane of the s…
Various Local Heating Events in the Earliest Phase of Flux Emergence
Toriumi, Shin; Cheung, Mark C. M.; Katsukawa, Yukio
Emerging flux regions (EFRs) are known to exhibit various sporadic local heating events in the lower atmosphere. To investigate the characteristics of these events, especially to link the photospheric magnetic fields and atmospheric dynamics, we analyze Hinode, Interface Region Imaging Spectrograph (IRIS), and Solar Dynamics Observatory data of a …