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Featured
Satellite Revolution In Oceanography - Space
Natural Sciences (Earth sciences)
Date of upload:
27.08.2015
Co-author:
Caption:
euronews knowledge brings you a fresh mix of the world's most interesting know-hows, directly from space and sci-tech experts. This video is a Euronews Knowledge feature from April 24, 2015.
Shock-wave radio probing of solar wind sources in coronal magnetic fields | Artem Koval
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
08.10.2021
Co-author:
Caption:
The Space Weather effects in the near-Earth environment as well as in atmospheres of other terrestrial planets arise by corpuscular radiation from the Sun, known as the solar wind. The solar magnetic fields govern the solar corona structure. Magnetic-field strength values in the solar wind sources - key information for modeling and forecasting the Space Weather climate - are derived from various solar space- and ground-based observations, but, so far not accounting for specific types of radio bursts. These are “fractured” type II radio bursts attributed to collisions of shock waves with coronal structures emitting the solar wind. Here, we report about radio observations of two “fractured” type II bursts to demonstrate a novel tool for probing of magnetic field variations in the solar wind
New insights about the past, present and future of solar magnetism | Quentin Noraz
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
19.01.2023
Co-author:
Caption:
The magnetic field of solar-type stars is generated and sustained through an internal dynamo process. This process is mostly determined by the combined action of turbulent convective motions and differential rotation. It can sometimes lead to magnetic cyclic variabilities, like the 11-years solar cycle. Evidence of magnetic cycles have been detected for other solar-type stars as well, ranging from a few years to a few tens of years. How are these cycles controlled? Observations and stellar evolution models show that solar-like stars spin-down during their main-sequence. In parallel, numerical simulations of these stars show that different regimes of differential rotation can be reach and are characterized with the Rossby number. Read more at https://espos.stream/2022/12/01/Noraz/.
Quasi-periodic pulsations in stellar flares
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
10.09.2015
Co-author:
Chloe Pugh, Valery Nakariakov
Abstract:
Quasi-periodic pulsations (QPPs) are a common feature of solar flares that are observed in many different wavelengths. Although QPPs appear not to be as abundant in white light Kepler flare light curves as they are in solar flares, albeit in different wavelengths the structure of the pulsations are strikingly similar, hinting that the same underlying processes govern both solar and stellar flares. Here we consider a special case, observed on KIC9655129, which shows evidence of multiple periodicities. We speculate that the presence of multiple periodicities is a good indication that the QPPs were caused by magnetohydrodynamic oscillations, further strengthening the case that the physical processes in operation during stellar flares are at least analogous to those in solar flares.
Accurate numerical solutions to the forward problem of local helioseismology
Natural Sciences (Mathematics)
Date of upload:
14.07.2016
Co-author:
Michael Leguèbe, Damien Fournier, Aaron C. Birch, Laurent Gizon in Collaboration with Inria team Magique3D
Abstract:
We compute acoustic Green’s functions in an axisymmetric solar background model, which may include a meridional flow and differential rotation. The wave equation is solved in the frequency domain using a finite element solver. A transparent boundary condition for the waves is implemented in the chromosphere, which represents a great improvement in computational efficiency compared to implementations based on ’sponge layers’. We perform various convergence studies that demonstrate that wave travel times can be computed with an accuracy of 0.001 s. This high level of numerical accuracy is required to interpret travel times in the deep interior, and is achieved thanks to a refined mesh in the near surface layers and around the source of excitation. The wave solver presented here lays the ground for future iterative inversion methods for flows in the deep solar interior.
Observations of Red Giants with SONG
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
03.08.2016
Co-author:
Abstract:
One of the outstanding and unforeseen results from the Kepler mission is our new insight and understanding of red giant stars. These highly evolved stars, which are in the last stages of their life, provide extremely useful information when trying to develop stellar evolutionary models. Furthermore, they show stochastically excited oscillations thus allowing to use asteroseismic techniques to derive conditions of the most internal layers. Bright giants stars are well suited to be studied with the 1m telescopes in the Stellar Observations Network Group project (SONG) using a high resolution echelle spectrograph performing high precision measurements of their the radial velocity. The prototype node- the Hertzsprung SONG telescope- was inaugurated in October 2014 and is located at the Teide Observatory on Tenerife and providing continuous and high quality observations since then, When selecting the best targets for SONG, a precision of 1-2 m/s per point is reachable using the iodine method and a number of red giants have been observed with the SONG telescope since scientific operation started. In this talk we present the first results of these specific campaigns for a few red giants in which eigenmodes have been identified and their global seismic parameters derived.
Comparison of damping mechanisms for transverse waves in coronal loops.
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
22.01.2017
Co-author:
I. Arregui
Abstract:
Damping of transverse waves in different solar coronal structures is a commonly observed property and a source of information about coronal conditions. Although resonant damping seems to be the most accepted mechanism for damping of transverse waves, there are other possible mechanisms. We have carried out a Bayesian analysis comparing three different models which could explain the damping in coronal loops. Our results indicate that resonant absorption is the most probable mechanism for low ratios between damping time and wave period, while the wave leakage mechanism is the best candidate for high ratios. Nonetheless, the evidence for one model against another shows a strong dependence on the data errors.
Gas towards the Gamma­-ray-­Emitting Supernova Remnant W28 (and others)
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
21.12.2015
Co-author:
Gavin Rowell, Matthieu Renaud, Phoebe de Wilt, Fabien Voisin, Yasuo Fukui, Michael Burton, Andrew Walsh, Akiko Kawamura, Andrew Walsh, Akiko Kawamura, Felix Aharonian
Abstract:
We present the results of molecular spectral line observations towards Supernova Remnants such as W28, RX J1713.7-3946 and HESS J1731-347. These remnants exhibit TeV gamma-ray emission, beacons for the presence of enhanced populations of high energy particles. It follows that these objects may accelerate Galactic cosmic-ray protons via the diffusive shock mechanism, but knowledge of the environment local to such remnants is required to constrain such scenarios. The Mopra radio telescope is ideal for probing the interstellar environments of HESS gamma-ray sources through large-scale molecular line surveys. Mopra can be employed to hunt for dense gas-tracing CS and NH3 transitions to identify potential cosmic-ray target material, while simultaneously searching for shock-tracing SiO emission lines which can directly highlight shock-disrupted gas. Furthermore, spectral line width gives an insight into gas dynamics and Mopra is capable of measuring this at a ~1' resolution over degree-scale regions. We present results from recent 7 and 12mm surveys towards the above-mentioned TeV-emitting Supernova Remnants and discuss the implications for distance, the diffusion of cosmic-rays and the high energy gamma-ray spectrum.
Survival and activity of bacteria in air: Why do we care?
Natural Sciences (Biology)
Date of upload:
25.04.2016
Co-author:
Kai Finster, Meilee Ling, Maher Sahyoun, Morten Dreyer, Stine Holm, Martin Rasmussen, Stephanie Pilgaard
Abstract:
The presentation deals with activity of airborne microbial cells and how this is important for expanding our understanding of habitability and biosignatures.
Field line helicity as a tool for coronal physics
Natural Sciences (Physics)
Date of upload:
22.11.2017
Co-author:
G. Hornig, M.H. Page
Abstract:
What if there were a way to identify **where** the magnetic helicity is concentrated within a three- dimensional magnetic field? At first sight this question appears meaningless, since magnetic helicity is an integral over the whole volume of the magnetic field. But, in fact, it is possible to decompose this total helicity as an integral over individual "field line helicities" for each magnetic field line in the domain. All of these are ideal-invariant, topological quantities, and they allow us to quantify in a meaningful way how magnetic helicity is distributed within the domain. In this talk, I will show how this idea can be practically applied to typical extrapolations of the Sun's coronal magnetic field that are used in solar physics.
Development of instrumentation for solar observations at the Brazilian National Institute for Space
Natural Sciences (Physics)
Date of upload:
15.11.2018
Co-author:
Abstract:
The solar electromagnetic and corpuscular emissions are strongly modulated by the evolution of the magnetic structure of the solar atmosphere, which is imprinted in the solar surface. The evolution of the magnetic structure leads to gradual changes in the solar activity (space climate) as well as violent events (space weather) that affect the whole Heliosphere. In particular, the solar output affects the ionized and neutral components of the Earth’s atmosphere that have a direct impact on human activities from agriculture to high-technological systems. The solar magnetism is driven by the energy transport from the inner layers to the solar atmosphere. Although systematic observations have revealed several features related to the evolution of solar activity, there is not a complete explanation of the physical processes that lead to solar activity cyclic variability and its long-term changes. Here we present a brief description of the development of a magnetograph and visible-light imager instrument to study the solar dynamo processes through observations of the solar surface magnetic field distribution. The instrument will provide measurements of the vector magnetic field and the line-of-sight velocity in the solar photosphere. As the magnetic field anchored at the solar surface produces most of the structures and energetic events in the upper solar atmosphere and significantly influences the Heliosphere, the development of this instrument plays an essential role in reaching the scientific goals of The Atmospheric and Space Science Coordination (CEA) at the Brazilian National Institute for Space Research (INPE). In particular, the INPE’s Space Weather program will benefit most from the development of this technology. Additionally, we expect that this project will be the starting point to establish a robust research program on Solar System Research at INPE. The proposed instrument has been designed to operate on the ground, but with a conceptual design flexible enough to be adapted to work on a balloon and space-based platforms. In this way, our main aim is acquiring know-how progressively to build state-of-art solar vector magnetograph and visible-light imagers for space-based platforms to contribute to the efforts of the solar-terrestrial physics community to address the main unanswered questions on how our nearby Star works.
The Science of EST
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
09.06.2020
Co-author:
Abstract:
1000
The Sun: a laboratory for stellar and plasma physics
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
27.03.2019
Co-author:
Abstract:
Community paper as part of the Denkschrift 2017 - Perspektiven der Astrophysik in Deutschland 2017 - 2030
How-To MLT_4
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
14.08.2018
Co-author:
Abstract:
Short How-To about how to call the MLT_ 4 recognition code.
The European Solar Telescope - Understanding Our Sun
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
03.07.2018
Co-author:
Abstract:
Here you can download the EST Brochure.
BSS Test 11:52 07-Feb
Natural Sciences (Physics)
Date of upload:
07.02.2020
Co-author:
Abstract:
1000
Inference of Solar Rotation from Perturbations of Acoustic Mode Eigenfunctions
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
07.12.2020
Co-author:
Ariane Schad
Abstract:
1000
Constraining the magnetic vector in the quiet solar photosphere and the impact of instrumental degradation
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
06.07.2021
Co-author:
R. J. Campbell , S. Shelyag, C. Quintero Noda, M. Mathioudakis, P. H. Keys, and A. Reid
Abstract:
1000
HOW TO DESIGN A FULL DISK TELESCOPE FOR SPRING
Natural Sciences (Astrophysics and Astrononmy)
Date of upload:
22.12.2021
Co-author:
Dirk Soltau (first author)
Abstract:
1000
The Sun, the stars, and solar-stellar relations
Natural Sciences (Astrophysics and Astrononmy)
Start date:
30.08.2015
End date:
03.09.2015
Location:
Freiburg, Germany
2nd SpaceInn Global Helioseismology Team Meeting
Natural Sciences (Astrophysics and Astrononmy)
Start date:
10.03.2015
End date:
12.03.2015
Location:
Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany
Celebrating Mopra: Looking to the Future
Natural Sciences (Astrophysics and Astrononmy)
Start date:
08.12.2015
End date:
10.12.2015
Location:
School of Physics, UNSW, Sydney, Australia
Ground-based Solar Observations in the Space Instrumentation Era
Natural Sciences (Astrophysics and Astrononmy)
Start date:
04.10.2015
End date:
08.10.2015
Location:
Coimbra (Portugal)
Seismology of the Sun and the Distant Stars 2016
Natural Sciences (Astrophysics and Astrononmy)
Start date:
10.07.2016
End date:
14.07.2016
Location:
Angra do Heroísmo, Terceira-Açores, Portugal
Towards a Multimodal Construction Grammar
Humanities (Linguistics)
Start date:
09.03.2016
End date:
11.03.2016
Location:
Osnabrück, Germany
SCORe16 Workshop
Natural Sciences (Astrophysics and Astrononmy)
Start date:
02.10.2016
End date:
06.10.2016
Location:
Aarhus, Denmark
Studies of the Deep Solar Meridonal Flow
Natural Sciences (Astrophysics and Astrononmy)
Start date:
28.11.2016
End date:
02.12.2016
Location:
Berne, Switzerland
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