Search Publications
Asymptotic g modes: Evidence for a rapid rotation of the solar core
Provost, J.; Corbard, T.; Turck-Chièze, S. +11 more
Context. Over the past 40 years, helioseismology has been enormously successful in the study of the solar interior. A shortcoming has been the lack of a convincing detection of the solar g modes, which are oscillations driven by gravity and are hidden in the deepest part of the solar body - its hydrogen-burning core. The detection of g modes is ex…
The magnetic connectivity of coronal shocks from behind-the-limb flares to the visible solar surface during γ-ray events
Rouillard, A. P.; Plotnikov, I.; Share, G. H.
Context. The observation of >100 MeV γ-rays in the minutes to hours following solar flares suggests that high-energy particles interacting in the solar atmosphere can be stored and/or accelerated for long time periods. The occasions when γ-rays are detected even when the solar eruptions occurred beyond the solar limb as viewed from Earth provid…
Improvement of solar-cycle prediction: Plateau of solar axial dipole moment
Kusano, K.; Shiota, D.; Imada, S. +2 more
Aims: We report the small temporal variation of the axial dipole moment near the solar minimum and its application to the solar-cycle prediction by the surface flux transport (SFT) model.
Methods: We measure the axial dipole moment using the photospheric synoptic magnetogram observed by the Wilcox Solar Observatory (WSO), the ESA/NASA So…
Blowout jets and impulsive eruptive flares in a bald-patch topology
Srivastava, A. K.; Mandrini, C. H.; Schmieder, B. +7 more
Context. A subclass of broad extreme ultraviolet (EUV) and X-ray jets, called blowout jets, have become a topic of research since they could be the link between standard collimated jets and coronal mass ejections (CMEs).
Aims: Our aim is to understand the origin of a series of broad jets, some of which are accompanied by flares and associated…
Computational helioseismology in the frequency domain: acoustic waves in axisymmetric solar models with flows
Gizon, Laurent; Birch, Aaron C.; Fournier, Damien +7 more
Context. Local helioseismology has so far relied on semi-analytical methods to compute the spatial sensitivity of wave travel times to perturbations in the solar interior. These methods are cumbersome and lack flexibility.
Aims: Here we propose a convenient framework for numerically solving the forward problem of time-distance helioseismology…
Magnetic reconnection during eruptive magnetic flux ropes
Lin, J.; Roussev, I. I.; Keppens, R. +1 more
Aims: We perform a three-dimensional (3D) high resolution numerical simulation in isothermal magnetohydrodynamics to study the magnetic reconnection process in a current sheet (CS) formed during an eruption of a twisted magnetic flux rope (MFR). Because the twist distribution violates the Kruskal-Shafranov condition, the kink instability occu…
Photospheric activity of the Sun with VIRGO and GOLF. Comparison with standard activity proxies
García, R. A.; Pallé, P. L.; Bertello, L. +3 more
We study the variability of solar activity using new photospheric proxies originally developed for the analysis of stellar magnetism with the CoRoT and Kepler photometric observations. These proxies were obtained by tracking the temporal modulations in the observations associated with the spots and magnetic features as the Sun rotates. We analyzed…
Photospheric and coronal magnetic fields in six magnetographs. II. Harmonic scaling of field intensities
Mursula, Kalevi; Virtanen, Ilpo
Context. Photospheric magnetic fields have been observed since the 1970s by several ground-based and satellite instruments. While the different instruments show a fairly similar large-scale structure and temporal evolution of the photospheric magnetic field, the magnetic field intensity varies significantly between the observations.
Aims: We …
Transition from eruptive to confined flares in the same active region
Aulanier, G.; Schmieder, B.; Chandra, R. +2 more
Context. Solar flares are sudden and violent releases of magnetic energy in the solar atmosphere that can be divided into two classes: eruptive flares, where plasma is ejected from the solar atmosphere resulting in a coronal mass ejection (CME), and confined flares, where no CME is associated with the flare.
Aims: We present a case study show…
Pre-flare coronal dimmings
Ji, H. S.; Zhang, Q. M.; Su, Y. N.
Context. Coronal dimmings are regions of decreased extreme-ultravoilet (EUV) and/or X-ray (originally Skylab, then Yohkoh/SXT) intensities, which are often associated with flares and coronal mass ejections (CMEs). The large-scale impulsive dimmings have been thoroughly observed and investigated. The pre-flare dimmings before the flare impulsive ph…