Search Publications
Recent theoretical and observational developments in magnetic helicity studies
Démoulin, P.
Magnetic helicity quantifies how the magnetic field is sheared and twisted compared to its lowest energy state (potential field). Such stressed magnetic fields are usually observed in association with flares, eruptive filaments, and coronal mass ejections (CMEs). Magnetic helicity plays a key role in magnetohydrodynamics because it is almost prese…
Orientations of LASCO Halo CMEs and their connection to the flux rope structure of interplanetary CMEs
Yurchyshyn, V.; Lynch, B. J.; Lepping, R. P. +2 more
Coronal mass ejections (CMEs) observed near the Sun via LASCO coronographic imaging are the most important solar drivers of geomagnetic storms. ICMEs, their interplanetary, near-Earth counterparts, can be detected in situ, for example, by the Wind and ACE spacecraft. An ICME usually exhibits a complex structure that very often includes a magnetic …
Measurements of magnetic helicity injected through the solar photosphere
Chae, Jongchul
The amount of magnetic helicity injected into the corona through the photosphere can be measured by inferring the apparent motion of photospheric footpoints of fieldlines from a time series of line-of-sight magnetograms, as originally proposed by [Chae, J., 2001. Observational determination of the rate of magnetic helicity transport through the so…
Temporal variations in solar rotation at the bottom of the convection zone: The current status
Thompson, M. J.; Howe, R.; Komm, R. +4 more
We present the most recent results on the short-period variations in the solar rotation rate near the base of the convection zone. The 1.3-year period which was reported in the early years of solar cycle 23 appears not to persist after 2001, but there are hints of fluctuations at a different period during the declining phase of the cycle.
Coronal mass ejections: Solar cycle aspects
St. Cyr, O. C.; Cremades, Hebe
Research in the area of coronal mass ejections (CMEs) is now mature, since their discovery coincided with the first coronagraph that was flown in space in 1971. However, the continuity of space coronagraphs and similar instruments has allowed the detection and measurement of CMEs over almost three consecutive solar cycles. Their importance in the …
The magnetic field topology associated with two M flares
Mandrini, C. H.; Démoulin, P.; Luoni, M. L. +1 more
On 27 October, 2003, two GOES M-class flares occurred in an interval of 3 h in active region NOAA 10486. The two flares were confined and their associated brightenings appeared at the same location, displaying a very similar shape both at the chromospheric and coronal levels. We focus on the analysis of magnetic field (SOHO/MDI), chromospheric (HA…
GIADA: The Grain Impact Analyser and Dust Accumulator for the Rosetta space mission
Lopez Moreno, J. J.; Rodriguez, J.; Colangeli, L. +13 more
The ESA ROSETTA mission will perform a rendezvous with comet 67P/Churyumov-Gerasimenko and will follow and study it from about 3.25 AU to perihelion at 1.34 AU and, during the foreseen extended mission, up to 2 AU post-perihelion, in order to observe for the first time the onset of activity of a comet and to follow its evolution. The GIADA (Grain …
Reconstruction of solar irradiance using the Group sunspot number
Solanki, S. K.; Krivova, N. A.; Balmaceda, L.
We present a reconstruction of total solar irradiance since 1610 to the present based on variations of the surface distribution of the solar magnetic field. The latter is calculated from the historical record of the Group sunspot number using a simple but consistent physical model. Our model successfully reproduces three independent data sets: tot…
How to improve the maps of magnetic helicity injection in active regions?
Démoulin, Pascal; Pariat, Etienne; Nindos, Alexander
Magnetic helicity, a topological quantity which measures the twist, the writhe and the shear of a magnetic field, has recently appeared as a key quantity to understand some mechanisms of the solar activity such as Coronal Mass Ejections and flare onset. It is thus becoming of major importance to be able to compute magnetic helicity in active regio…
Emission heights of coronal bright points on Fe XII radiance map
Tu, C. -Y.; Marsch, E.; Tian, H. +1 more
The study of coronal bright points (BPs) is important for understanding coronal heating and the origin of the solar wind. Previous studies indicated that coronal BPs have a highly significant tendency to coincide with magnetic neutral lines in the photosphere. Here we further studied the emission heights of the BPs above the photosphere in the bip…