We use daily full-disk vector magnetograms from Vector Spectromagnetograph (VSM) on Synoptic Optical Long-term Investigations of the Sun (SOLIS) system to synthesize the first Carrington maps of the photospheric vector magnetic field. We describe these maps and make a comparison of observed radial field with the radial field estimate from LOS magnetograms. Further, we employ these maps to study the hemispheric pattern of current helicity density, H c , during the rising phase of the solar cycle 24. Longitudinal average over the 23 consecutive solar rotations shows a clear signature of the hemispheric helicity rule, i.e. H c is predominantly negative in the North and positive in South. Although our data include the early phase of cycle 24, there appears no evidence for a possible (systematic) reversal of the hemispheric helicity rule at the beginning of cycle as predicted by some dynamo models. Further, we compute the hemispheric pattern in active region latitudes (-30 • ≤ θ ≤ 30 • ) separately for weak (100< |B r | <500 G)and strong (|B r | >1000 G) radial magnetic fields. We find that while the current helicity of strong fields follows the well-known hemispheric rule (i.e., θ·H c < 0), H c of weak fields exhibits an inverse hemispheric behavior (i.e., θ·H c > 0) albeit with large statistical scatter. We discuss two plausible scenarios to explain the opposite hemispheric trend of helicity in weak and strong field region.

Abstract.The results of the first observations of a zebra pattern at frequencies around 5.6 GHz are presented. The fine structures in the emission spectrum were recorded simultaneously by the Siberian Solar Radiotelescope and the spectropolarimeters of the National Astronomical Observatories, which allowed us to study the presented event with high spatial, temporal and spectral resolution. The apparent source size does not exceed 10 arcsec, and the sources of the different stripes of the zebra structure coincide spatially. The circular polarization degree reaches 100%, and the polarization sense corresponds to the extraordinary wave. We argue that the most probable generation mechanism of the zebra pattern is nonlinear coupling of Bernstein waves. In this case the value of the magnetic field in the burst source, determined by the frequency separation between the adjacent stripes, is 60-80 G.

On 17 January 2010, STEREO-B observed in extreme ultraviolet (EUV) and white light a large-scale dome-shaped expanding coronal transient with perfectly connected off-limb and on-disk signatures. Veronig et al. (2010, ApJL 716, 57) concluded that the dome was formed by a weak shock wave. We have revealed two EUV components, one of which corresponded to this transient. All of its properties found from EUV, white light, and a metric type II burst match expectations for a freely expanding coronal shock wave including correspondence to the fast-mode speed distribution, while the transient sweeping over the solar surface had a speed typical of EUV waves. The shock wave was presumably excited by an abrupt filament eruption. Both a weak shock approximation and a power-law fit match kinematics of the transient near the Sun. Moreover, the power-law fit matches expansion of the CME leading edge up to 24 solar radii. The second, quasi-stationary EUV component near the dimming was presumably associated with a stretched CME structure; no indications of opening magnetic fields have been detected far from the eruption region.

No abstract

We continue our study (Grechnev et al. (2013),