Eruptions from coronal hole bright points : observations and non-potential modeling

Funding: DHM would like to thank the Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214).Context. We report on the third part of a series of studies on eruptions associated with small-scale loop complexes named coronal bright points (CBPs). Aims. A single case study of a CBP in an equatorial coronal hole with an exceptionally large size is investigated to extend our understanding of the formation of mini-filaments (MFs), their destabilisation and the origin of the eruption triggering the formation of jet-like features recorded in the extreme-ultraviolet (EUV) and X-ray emission. We aim to explore the nature of the so called micro-flares in CBPs associated with jets in coronal holes and mini coronal mass ejections in the quiet Sun. Methods. Co-observations from the Atmospheric Imaging Assembly (AIA) and Helioseismic Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO), and GONG Halpha images are used together with a Non-Linear Force Free Field (NLFFF) relaxation approach, where the latter is based on a time series of HMI line-of-sight magnetograms. Results. A mini-filament (MF) that formed beneath the CBP arcade around 3–4 h before the eruption is seen in the Halpha and EUV AIA images to lift up and erupt triggering the formation of an X-ray jet. No significant photospheric magnetic flux concentration displacement (convergence) is observed and neither is magnetic flux cancellation between the two main magnetic polarities forming the CBP in the time period leading to the MF liftoff. The CBP micro-flare is associated with three flare kernels that formed shortly after the MF liftoff. No observational signature is found for reconnection beneath the erupting MF. The applied NLFFF modeling successfully reproduces both the CBP loop complex as well as the magnetic flux rope that hosts the MF. Conclusions. The applied NLFFF modellng is able to clearly show that an initial potential field can be evolved into a non-potential magnetic field configuration that contains free magnetic energy in the region that observationally hosts the eruption. The comparison of the magnetic field structure shows that the magnetic NLFFF model contains many of the features that can explain the dfferent observational signatures found in the evolution and eruption of the CBP. In future it may eventually indicate the location of destabilisation that results in the eruptions of flux ropes.Publisher PDFPeer reviewe

STELLAR : a EU twinning project on LOFAR data analysis and knowledge transfer

The Scientific and Technological Excellence by Leveraging LOFAR Advancements in Radio Astronomy (STELLAR) is a project of mutual collaboration and know-how transfer in the field of radio astronomy, solar physics and space weather using the LOFAR instrument and data. Two institutions from Bulgaria, benefit from technical and scientific know-how exchange from world- leading RA institutions - ASTRON (the Netherlands) and DIAS (Ireland) via series of training hands-on sessions, workshops, seminars and project-focused schools for both students and senior staff. The poster presents the activities so far and future plans. All results, links to videos and outreach activities are hosted at a dedicated web-site. The STELLAR project is funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 952439. It is coordinated by the Institute of Astronomy, Bulgarian Academy of Sciences

Review of solar energetic particle models

Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they are the product of a broad set of physical processes from the corona out through the extent of the heliosphere, and provide insight into processes of particle acceleration and transport that are widely applicable in astrophysics. From the operations perspective, SEP events pose a radiation hazard for aviation, electronics in space, and human space exploration, in particular for missions outside of the Earth’s protective magnetosphere including to the Moon and Mars. Thus, it is critical to improve the scientific understanding of SEP events and use this understanding to develop and improve SEP forecasting capabilities to support operations. Many SEP models exist or are in development using a wide variety of approaches and with differing goals. These include computationally intensive physics-based models, fast and light empirical models, machine learning-based models, and mixed-model approaches. The aim of this paper is to summarize all of the SEP models currently developed in the scientific community, including a description of model approach, inputs and outputs, free parameters, and any published validations or comparisons with data.</p

LOFAR-BG Current State

In May 2020, the infrastructure project LOFAR- BG, coordinated by the Institute of Astronomy and National Astronomical Observatory (IANAO), was approved for inclusion in the updated National Roadmap for Scientific Infrastructure 2020-2027 (NRSI), created and supported by Bulgaria’s Ministry of Education and Science. Currently, members of the national consortium for managing the project also include the Dept. of Astronomy of Sofia University, the Dept. of Astronomy of Shumen University, as well as the Dept. of Radio Communication and Video Technologies of the Technical University-Sofia. In the future, we will be adding new partners to the consortium

Review of Solar Energetic Particle Models

Solar Energetic Particles (SEP) events are interesting from a scientific perspective as they are the product of a broad set of physical processes from the corona out through the extent of the heliosphere, and provide insight into processes of particle acceleration and transport that are widely applicable in astrophysics. From the operations perspective, SEP events pose a radiation hazard for aviation, electronics in space, and human space exploration, in particular for missions outside of the Earth’s protective magnetosphere including to the Moon and Mars. Thus, it is critical to imific understanding of SEP events and use this understanding to develop and improve SEP forecasting capabilities to support operations. Many SEP models exist or are in development using a wide variety of approaches and with differing goals. These include computationally intensive physics-based models, fast and light empirical models, machine learning-based models, and mixed-model approaches. The aim of this paper is to summarize all of the SEP models currently developed in the scientific community, including a description of model approach, inputs and outputs, free parameters, and any published validations or comparisons with data