Related papers: Coronal Hole Detection and Open Magnetic Flux
On 21 August 2017 a total solar eclipse swept across the contiguous United States providing excellent opportunities for diagnostics of the Sun's corona. The Sun's coronal structure is notoriously difficult to observe except during solar…
Solar "magnetic tornadoes" are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that such rotating features are an integral part of…
We used our newly developed magnetohydrodynamic (MHD) code to perform 2.5D simulations of a fast-mode MHD wave interacting with coronal holes (CH) of varying Alfv\'en speed which result from assuming different CH densities. We find that…
The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometres per…
Data from recent numerical simulations of the solar corona and transition region are analysed and the magnetic field connection between the low corona and the photosphere is found to be close to that of a potential field. The fieldline to…
Sunspots on the surface of the Sun are the observational signatures of intense manifestations of tightly packed magnetic field lines, with near-vertical field strengths exceeding 6,000 G in extreme cases. It is well accepted that both the…
Coronal hole boundaries are the interfaces between closed and open magnetic field regions in the solar atmosphere. Many fundamental processes take place at these regions, including magnetic reconnection that is responsible for solar wind…
We use data at 131, 171, and 304 A from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) to search for hot flux ropes in 141 M-class and X-class solar flares that occurred at solar longitudes equal to or…
The present spectroscopic study of the ultraviolet coronal emission in a polar hole, detected on April 6-9, 1996 with the Ultraviolet Coronagraph Spectrometer aboard the SOHO spacecraft, identifies the inter-plume lanes and background…
The magnetic field in the Sun's corona stores energy that can be released to heat the coronal plasma and drive solar eruptions. Measurements of the global coronal magnetic field have been limited to a few snapshots. We present observations…
Faraday rotation measurements of extragalactic radio sources occulted by the solar corona serve as a powerful complementary tool for probing the pre-eruption electron density and magnetic field structure. These measurements thereby allow us…
Eruptions of coronal mass ejections (CMEs) from the Sun are usually associated with a number of signatures that can be identified in solar disc imagery. However, there are cases in which a CME that is well observed in coronagraph data is…
The hemispheric pattern of solar filaments is considered in the context of the global magnetic field of the solar corona. In recent work Mackay and van Ballegooijen have shown how, for a pair of interacting magnetic bipoles, the observed…
Coronal jets are transient narrow features in the solar corona that originate from all regions of the solar disk: active regions, quiet sun, and coronal holes. Recent studies indicate that at least some coronal jets in quiet regions and…
Measuring the magnetic helicity distribution in the solar corona can help in understanding the trigger of solar eruptive events because magnetic helicity is believed to play a key role in solar activity due to its conservation property. A…
Observations of surface magnetic fields are now within reach for many stellar types thanks to the development of Zeeman-Doppler Imaging. These observations are extremely useful for constraining rotational evolution models of stars, as well…
We developed a new numerical code that is able to perform 2.5D simulations of a magnetohydrodynamic (MHD) wave propagation in the corona, and its interaction with a low density region, such as a coronal hole (CH). We show that the impact of…
The shapes of solar coronal loops are sensitive to the presence of electrical currents that are the carriers of the nonpotential energy available for impulsive activity. We use this information in a new method for modeling the coronal…
Small-scale magnetic flux emergence in the quiet Sun is crucial for maintaining solar magnetic activity. On the smallest scales studied so far, namely within individual granules, two mechanisms have been identified: emergence in tiny…
Magnetic clouds (MCs) are twisted magnetic structures ejected from the Sun and probed by in situ instruments. They are typically modeled as flux ropes (FRs). The determination of the FR global characteristics requires the estimation of the…