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Astrophysics and Astrononmy
High-resolution spectroscopy of a minifilament eruption | Ioannis Kontogiannis
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
21.10.2021
Caption:
Minifilaments are miniature versions of filaments, first observed in H-alpha filtergrams of quiet Sun. Recent studies have showcased their association with small-scale eruptive events, highlighting their importance in energetic processes of the quiet Sun. We present the first detailed study of such an event, using high-cadence, high-spectral resolution imaging observations. The minifilament formed between small-scale, opposite-polarity magnetic concentrations and erupted within an hour after its appearance in H-alpha, exhibiting a twisted, thread-like structure. Its eruption took place in two phases (slow and fast), producing a coronal dimming, while part of the erupting material returned to the chromosphere. The observed similarities to large-scale filament eruptions indicate the action o
Validation of a wave heated 3D MHD coronal-wind model using Polarized Brightness and EUV observations | Susanna Parenti
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
02.04.2022
Caption:
The 3D MHD global modeling is a powerful tool to test all the possible candidate physical processes responsible for the formation and evolution of the corona and heliosphere. To fully understand the possible role of each of these mechanisms, we need a validation process where the output from the simulations is quantitatively compared to the observational data. In this work, we present the results from our validation process applied to the wave turbulence driven 3D MHD corona-wind model WindPredict-AW.
Read more at https://espos.stream/2022/03/31/Susanna-Parenti/
On the Differences in the Periodic Behavior of Magnetic Helicity Flux in Flaring Active Regions | Szabolcs Soós
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
03.03.2022
Caption:
Observational precursors of large solar flares provide a basis for future operational systems for forecasting. We studied the evolution of the normalized emergence (EM), shearing (SH), and total (T) magnetic helicity flux components for 14 flaring (with at least one X-class flare) and 14 nonflaring (
Helioseismology of Sunspots - On the Detection of Subsurface Structure and Evolution (numerical simulations)
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
30.07.2021
Co-author:
Prof. Dr. M. Roth
Caption:
We simulate the seismic propagation of a single wave packet through a stabilized solar atmosphere, including a magnetic fluxtube. The initial wave packet interacts with the flux tube, giving rise to mode conversion. Here we observe downward propagation through the flux tube, triggering a re-emerging wave that carries information about the subsurface structure of the flux tube. The video includes the horizontal and vertical velocity component, for magnetic and quiet simulations, plus the instantaneous difference for different depth scopes.
Formation and disappearance of a penumbra: Recent results | Mariarita Murabito
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
23.02.2022
Caption:
The physical conditions resulting in the formation and disappearance of penumbral regions are poorly understood. We investigated these conditions by using high-resolution spectropolarimetric observations of a sunspot penumbra from different instruments at ground- and space-based telescopes, namely the SST/CRISP, SDO/HMI, and Hinode/SP. The studied data allowed us to assess the evolution of the magnetic and velocity properties of plasma in the observed region and to analyze the role of several processes found therein. The penumbra forms only on one side of the observed region, characterized by the absence of an overlying magnetic canopy. The penumbra later disappears progressively in time and space. This final evolution of the studied region seems to be governed by the presence of moving ma
Helioseismology of Sunspots - On the Detection of Subsurface Structure and Evolution
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
30.07.2021
Co-author:
Prof. Dr. M. Roth, Dr. G. Vigeesh, K. Glogowski
Caption:
We track a total of 10 active regions, including corresponding quiet-Sun regions, using HMI Doppler-velocity data. The regions are analyzed using methods of local helioseismology, to study the subsurface structure and evolution of active regions. The full video includes the active regions (AR) and emerging active regions (EAR): EAR 11072, EAR 11105, EAR 11130, EAR 11158, EAR 11768, AR 11823, AR 11899, AR 12079, AR 12090, AR 12246.
Probing the Spatial Scales of Coronal Loops with NASA’s High-resolution Coronal Imager (Hi-C) | Thomas Williams
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
09.09.2022
Caption:
NASA’s Sounding Rocket Program has provided essential contributions to space science since 1959 and has proved to be one of the most robust, versatile, and cost-effective flight programs at NASA. On the 29th May 2018, the High-resolution Coronal Imager (Hi-C) was launched for a third time from the White Sands Missile Range, NM, USA capturing 329 seconds of 17.2 nm data of target active region AR 12712, with a cadence of ~4s and a plate scale of ~0.129 arcsec. This unique dataset provides some of the highest-resolution EUV observations of coronal loops to date. In this presentation, the spatial scales of these fundamental building blocks of the solar corona are explored and the results from Hi-C are discussed with respect to SDO/AIA and Solar Orbiter.
The Horizontal Poynting Flux in the Solar Photosphere | Suzana S. A. Silva
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
15.06.2022
Caption:
A crucial step for understanding the origin of the high temperatures in the upper atmosphere is an accurate description of the energy transport. Current studies on the energy flux in the solar atmosphere mainly focus on the vertical electromagnetic flow through the photosphere, ignoring the possible Poynting flux’s contributions to local heating. This study used observational data from Sunrise/IMaX and Bifrost simulations to analyse the electromagnetic energy flux of the lower atmosphere. Based on a simulated quiet Sun atmosphere, we found that only a small fraction of the Poynting energy flows upwards in the photosphere. See more at https://espos.stream/2022/06/09/Silva/.
Coronal modelling: the good, the bad and the ugly | Michaela Brchnelova
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
20.10.2022
Caption:
Space weather forecasting is a complex problem which involves modeling of the solar plasma all the way from the solar corona down to the Earth’s atmosphere. To simulate this energy transfer, a cascade of various models is required, such as the coronal model, the heliospheric model and various models to estimate the Kp and Dst indices. European efforts to create such a framework of connected tools have resulted in the launch of the Virtual Space Weather Modeling Center (VSWMC) (Poedts et al., 2019) - a platform we will briefly introduce in the beginning of this talk.
Read further at https://espos.stream/2022/10/20/Brchnelova/.
Insights into the solar spicule forest from simulations and laboratory experiments | Piyali Chatterjee
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
17.11.2022
Caption:
Spicular jets are highly elongated chromospheric plasma features that are believed to transport momentum to the solar wind and non-thermal energy to heat the atmosphere. At any given time, it is estimated that about 3 million spicules are present on the Sun. We find an intriguing parallel between the simulated spicular forest in a solar-like atmosphere and the numerous jets of polymeric fluid in the laboratory when both are subjected to harmonic forcing. In our radiative (both 2D and 3D) MHD simulations with sub-surface convection, the solar surface oscillations are excited similarly to those harmonic vibrations. A forest of spicules are formed in our simulations with heights ranging between 6 and 25 Mm, bearing substantially closer resemblance to clusters of jets observed in the solar atm
Long-term variation of quiet sun Mg II h&k lines and its relation with the solar cycle | Ricardo Gafeira
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
20.01.2023
Caption:
The solar atmosphere undergoes several changes during the solar cycle. Those changes can be identified by observing several solar features and their respective dynamics, which can be observed in many different wavelengths, and by analyzing the variations in the total solar irradiance. The latter is characterized by an increase in the total solar irradiance during the solar maximum and a decrease in the decay phase. In this talk, we will present the intensity variations of the Mg II h&k lines emission peak, observed by IRIS, under quiet sun conditions close to the disk center over the decaying phase of the solar cycle. The observed variations will then be interpreted and put in the context of the solar atmospheric physical conditions.
Heating and non-thermal motions in a coronal loop | Cosima Breu
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
08.12.2022
Caption:
Observed spectral profiles of emission lines from the corona are found to have widths exceeding the thermal line width. To investigate the physical mechanism behind this, we run a 3D MHD model of a single loop in which we partially resolve the turbulent motions within the loop and the substructures that form self-consistently in response to the driving by magneto-convection in the photosphere. The loop is modelled as a straightened-out magnetic flux tube with a shallow, self-consistently evolving convection zone layer at each end. This allows us to include the response of the chromosphere to heating events. From the model we synthesize spectral profiles of emission lines. We investigate the strongest heating events in the coronal loop and discuss the relation between footpoint motions and
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