Related papers: Low-latitude coronal holes, decaying active region…
Magnetic fields in the solar corona are responsible for a wide range of phenomena. However, any direct measurements of the coronal magnetic fields are very difficult due to lack of suitable spectral lines, weak magnetic fields, and high…
The emergence of magnetic flux from the convection zone into the corona is an important process for the dynamical evolution of the coronal magnetic field. In this paper we extend our previous numerical investigations, by looking at the…
Rapidly decaying long-period oscillations often occur in hot coronal loops of active regions associated with small (or micro-) flares. This kind of wave activity was first discovered with the SOHO/SUMER spectrometer from Doppler velocity…
Extrapolation codes for modelling the magnetic field in the corona in cartesian geometry do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, \textit{e.g.}, a single active region.…
Coronal structure of active regions appearing in coronal holes is studied by using the data obtained with the Soft X-Ray Telescope (SXT) aboard {\it Yohkoh} from 1991 November to 1993 March. The following characteristics are found; Many of…
Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal phenomena at all scales. We employed STEREO/COR1 data obtained during a deep minimum of solar activity in February 2008…
The interaction between emerging active regions and the pre-existing coronal magnetic field is important to understand better the mechanisms of storage and release of magnetic energy from the convection zone to the high corona. We are…
Using advanced processing techniques, we analyze high-cadence, high-resolution extreme ultraviolet images and show that, throughout the solar cycle, mid-latitude coronal holes (CHs) are made up of ubiquitous and space-filling funnel-shaped…
The solar magnetic field is the primary agent that drives solar activity and couples the Sun to the Heliosphere. Although the details of this coupling depend on the quantitative properties of the field, many important aspects of the corona…
Adopting the thermal free-free emission mechanism, the coronal and chromospheric magnetic fields are derived from the polarization and spectral observations with the Nobeyama Radioheliograph at 1.76 cm. The solar active regions (AR) located…
Plasma upflows with a Doppler shift exceeding -10 km/s at active region (AR) boundaries are considered potential sources of the nascent slow solar wind. We investigate the driving mechanisms of a pair of coronal upflow regions on the…
Remote and in-situ observations strongly imply that the slow solar wind consists of plasma from the hot, closed-field corona that is released onto open magnetic field lines. The Separatrix Web (S-Web) theory for the slow wind proposes that…
Coronal dimmings are transient depletions of coronal plasma observed in extreme ultraviolet and soft X-rays, interpreted as low-corona signatures of coronal mass ejections (CMEs). Their evolution is closely linked to CME dynamics, flare…
The heliospheric magnetic field is of pivotal importance in solar and space physics. The field is rooted in the Sun's photosphere, where it has been observed for many years. Global maps of the solar magnetic field based on full disk…
A statistical survey of 26 major electron events during the period 2002 February through the end of solar cycle 23 is presented. We have obtained electron solar onset times and the peak flux spectra for each event by fitting to a powerlaw…
Global magnetic field models use as input synoptic data, which usually show "aging effects" as the longitudinal 360{\deg} information is not obtained simultaneously. Especially during times of increased solar activity, the evolution of the…
An application of active contours without edges is presented as an efficient and effective means of extracting and characterizing coronal holes. Coronal holes are regions of low-density plasma on the Sun with open magnetic field lines. As…
Regularities of formation of coronal holes (CH) at the rising phase of cycle 23 are investigated. The period from 01.01.1997 to 01.03.2000 (Carrington rotations (CRs) 1918-2059) is considered in detail. The evolution of the global magnetic…
Recent advances have made it possible to obtain two-dimensional line-of-sight magnetic field maps of the solar corona from spectropolarimetric observations of the Fe XIII 1075 nm forbidden coronal emission line. Together with the linear…
The motion of faint propagating disturbances (PD) in the solar corona reveals an intricate structure which must be defined by the magnetic field. Applied to quiet Sun observations by the Atmospheric Imaging Assembly (AIA)/Solar Dynamics…