Solar H-alpha features with hot onsets. IV. Network fibrils

The solar chromosphere observed at 1 Hz and 0."2 resolution

We recently reported extremely rapid changes in chromospheric fine structure observed using the IBIS instrument in the red wing of H alpha. Here, we examine data obtained during the same observing run (August 7 2010), of a mature active region NOAA 11094. We analyze more IBIS data including wavelength scans and data from the Solar Dynamics Observatory, all from within a 30 minute interval. Using a slab radiative transfer model, we investigate the physical nature of fibrils in terms of tube-like vs. sheet-like structures. Principal Component Analysis shows that the very rapid H alpha variations…

ALMA small-scale features in the quiet Sun and active regions

Aims. The main aim of the present analysis is to decipher (i) the small-scale bright features in solar images of the quiet Sun and active regions obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and (ii) the ALMA correspondence of various known chromospheric structures visible in the H-alpha images of the Sun. Methods. Small-scale ALMA bright features in the quiet Sun region were analyzed using single-dish ALMA observations (1.21 mm, 248 GHz) and in an active region using interferometric ALMA measurements (3 mm, 100 GHz). With the single-dish observations, a full-disk sola…

Quiet-Sun hydrogen Lyman-alpha line profile derived from SOHO/SUMER solar-disk observations

The solar radiation in the Lyman-alpha spectral line of hydrogen plays a significant role in the illumination of chromospheric and coronal structures, such as prominences, spicules, chromospheric fibrils, cores of coronal mass ejections, and solar wind. Moreover, it is important for the investigation of the heliosphere, Earth's ionosphere, and the atmospheres of planets, moons, and comets. We derive a reference quiet-Sun Lyman-alpha spectral profile that is representative of the Lyman-alpha radiation from the solar disk during a minimum of solar activity. This profile can serve as an incident …

Ellerman Bombs at high resolution: I. Morphological evidence for photospheric reconnection

High-resolution imaging-spectroscopy movies of solar active region NOAA 10998 obtained with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish 1-m Solar Telescope show very bright, rapidly flickering, flame-like features that appear intermittently in the wings of the Balmer H-alpha line in a region with moat flows and likely some flux emergence. They show up at regular H-alpha blue-wing bright points that outline magnetic network, but flare upward with much larger brightness and distinct "jet" morphology seen from aside in the limbward view of these movies. We classify these features …

由 NVST、SDO 和 STEREO-A 观测揭示的一个倒 U 形太阳暗条爆发的触发机制

Onset mechanism of an inverted U-shaped solar filament eruption revealed by NVST, SDO, and STEREO-A observations

基于多视角观测与磁场重建，研究了倒U形太阳暗条爆发机制，发现新浮磁通量触发磁重联释放约束磁场，促使高扭缠磁通量绳爆发。

Excitation of an Outflow From the Lower Solar Atmosphere and a Co-Temporal EUV Transient Brightening

We analyse an absorption event within the H$α$ line wings, identified as a surge, and the co-spatial evolution of an EUV brightening, with spatial and temporal scales analogous to a small blinker. We conduct a multi-wavelength, multi-instrument analysis using high-cadence, high-resolution data, collected by the Interferometric BIdimensional Spectrometer on the Dunn Solar Telescope, as well as the space-borne Atmospheric Imaging Assembly and Helioseismic and Magnetic Imager instruments onboard the Solar Dynamics Observatory. One large absorption event situated within the plage region trailing t…

Production of 26Al, 44Ti, and 60Fe in Core-Collapse Supernovae: Sensitivity to the Rates of the Triple Alpha and 12C(a,g)16O Reactions

We have studied the sensitivity to variations in the the triple alpha and 12C(a,g)16O reaction rates of the production of 26Al, 44Ti, and 60Fe in core-collapse supernovae. We used the KEPLER code to model the evolution of 15, 20, and 25 solar mass stars to the onset of core collapse and simulated the ensuing supernova explosion using a piston model for the explosion. Calculations were performed for the Anders and Grevesse (1989) and Lodders (2003) abundances. Over a range of twice the experimental uncertainty, sigma, for each helium-burning rate, the production of 26Al, 60Fe, and their ratio v…

Small-scale structure and dynamics of the chromospheric magnetic field

Recent advances in observational performance and numerical simulations have revolutionised our understanding of the solar chromosphere. This concerns in particular the structure and dynamics on small spatial and temporal scales. As a result, the picture of the solar chromosphere changed from an idealised static and plane-parallel stratification to a complex compound of intermittent domains, which are dynamically coupled to the layers below and above. In this picture, the chromosphere in a stricter sense is associated with the typical fibrillar structure shaped by magnetic fields like it is kno…

Nonlinear Evolution of Ion Kinetic Instabilities in the Solar Wind

In-situ observations of the solar wind (SW) plasma from 0.29 to 1AU show that the protons and alpha particles are often non-Maxwellian, with evidence of kinetic instabilities, temperature anisotropies, differential ion streaming, and associated magnetic fluctuations spectra. The kinetic instabilities in the SW multi-ion plasma can lead to preferential heating of alpha particles and the dissipation of magnetic fluctuation energy, affecting the kinetic and global properties of the SW. Using for the first time a three-dimensional hybrid model, where ions are modeled as particle using the Particle…