Search Publications
The writhe of helical structures in the solar corona
Török, T.; Kliem, B.; Berger, M. A.
Context. Helicity is a fundamental property of magnetic fields, conserved in ideal MHD. In flux rope geometry, it consists of twist and writhe helicity. Despite the common occurrence of helical structures in the solar atmosphere, little is known about how their shape relates to the writhe, which fraction of helicity is contained in writhe, and how…
How to deal with measurement errors and lacking data in nonlinear force-free coronal magnetic field modelling?
Inhester, B.; Wiegelmann, T.
Context. The measured solar photospheric magnetic field vector is extrapolated into the solar corona under the assumption of a force-free plasma. In the generic case this problem is nonlinear.
Aims: We aim to improve an algorithm for computing the nonlinear force-free coronal magnetic field. We are in particular interested to incorporate meas…
The role of aerodynamic drag in propagation of interplanetary coronal mass ejections
Möstl, C.; Vršnak, B.; Vennerstrom, S. +3 more
Context. The propagation of interplanetary coronal mass ejections (ICMEs) and the forecast of their arrival on Earth is one of the central issues of space weather studies.
Aims: We investigate to which degree various ICME parameters (mass, size, take-off speed) and the ambient solar-wind parameters (density and velocity) affect the ICME Sun-E…
Asymmetries of solar coronal extreme ultraviolet emission lines
Peter, H.
Context. The profiles of emission lines formed in the corona contain information on the dynamics and the heating of the hot plasma. Only recently has data with sufficiently high spectral resolution become available for investigating the details of the profiles of emission lines formed well above 106 K. These show enhanced emission in th…
Velocity vectors of a quiescent prominence observed by Hinode/SOT and the MSDP (Meudon)
Schmieder, B.; Chandra, R.; Berlicki, A. +1 more
Context. The dynamics of prominence fine structures present a challenge to our understanding of the formation of cool plasma prominence embedded in the hot corona.
Aims: Observations performed by the high resolution Hinode/SOT telescope allow us to compute velocities perpendicular to the line-of-sight or transverse velocities. Combining simul…
Reconstructing the solar integrated radial velocity using MDI/SOHO
Meunier, N.; Lagrange, A. -M.; Desort, M.
Context. Searches for exoplanets with radial velocity techniques are increasingly sensitive to stellar activity. It is therefore crucial to characterize how this activity influences radial velocity measurements in their study of the detectability of planets in these conditions.
Aims: In a previous work we simulated the impact of spots and pla…
Observations of a rotating macrospicule associated with an X-ray jet
Solanki, S. K.; Inhester, B.; Curdt, W. +2 more
Aims: We attempt to understand the driving mechanism of a macrospicule and its relationship with a coronal jet.
Methods: We study the dynamics of a macrospicule and an associated coronal jet captured by multi-spacecraft observations. Doppler velocities in both the macrospicule and the coronal jet are determined by EIS and SUMER spectra. …
Flux emergence and coronal eruption
Hood, A. W.; Archontis, V.
Aims: Our aim is to study the photospheric flux distribution of a twisted flux tube that emerges from the solar interior. We also report on the eruption of a new flux rope when the emerging tube rises into a pre-existing magnetic field in the corona.
Methods: To study the evolution, we use 3D numerical simulations by solving the time-dep…
A precise measurement of the solar differential rotation by tracing small bright coronal structures in SOHO-EIT images. Results and comparisons for the period 1998-2006
Hanslmeier, A.; Wöhl, H.; Brajša, R. +1 more
Aims: We precisely determine the solar rotation velocity during most of the 23rd solar cycle, in the years 1998-2006. We measure the solar differential rotation by tracing small bright coronal structures (SBCS) in SOHO-EIT images.
Methods: The 28.4 nm EIT channel was used and positions of more than 55 000 structures were measured applyin…
Comparing eclipse observations of the 2008 August 1 solar corona with an MHD model prediction
Riley, P.; Linker, J. A.; Mikić, Z. +7 more
Context. The structure of the white-light and emission solar coronas and their MHD modelling are the context of our work.
Aims: A comparison is made between the structure of the solar corona as observed during the 2008 August 1 total eclipse from Mongolia and that predicted by an MHD model.
Methods: The model has an improved energy formu…