Photospheric Plasma Flows Around a Solar Spot (original) (raw)

Photospheric plasma and magnetic field dynamics during the formation of solar AR 11190

Astronomy & Astrophysics, 2019

Context.The Sun features on its surface typical flow patterns called the granulation, mesogranulation, and supergranulation. These patterns arise due to convective flows transporting energy from the interior of the Sun to its surface. The other well known elements structuring the solar photosphere are magnetic fields arranged from single, isolated, small-scale flux tubes to large and extended regions visible as sunspots and active regions.Aims.In this paper we will shed light on the interaction between the convective flows in large-scale cells as well as the large-scale magnetic fields in active regions, and investigate in detail the statistical distribution of flow velocities during the evolution and formation of National Oceanic and Atmospheric Administration active region 11190.Methods.To do so, we employed local correlation tracking methods on data obtained by the Solar Dynamics Observatory in the continuum as well as on processed line-of-sight magnetograms.Results.We find that ...

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

Solar Physics

Seeking to establish whether active-region upflow material contributes to the slow solar wind, we examine in detail the plasma upflows from Active Region (AR) 10978, which crossed the Sun’s disc in the interval 8 to 16 December 2007 during Carrington rotation (CR) 2064. In previous work, using data from the Hinode/EUV Imaging Spectrometer, upflow velocity evolution was extensively studied as the region crossed the disc, while a linear force-free-field magnetic extrapolation was used to confirm aspects of the velocity evolution and to establish the presence of quasi-separatrix layers at the upflow source areas. The plasma properties, temperature, density, and first ionisation potential bias [FIP-bias] were measured with the spectrometer during the disc passage of the active region. Global potential-field source-surface (PFSS) models showed that AR 10978 was completely covered by the closed field of a helmet streamer that is part of the streamer belt. Therefore it is not clear how any...

Rotation of Plasma in Sunspots

Solar Physics, 1998

In this paper we present the results of a sunspot rotation study using Abastumani Astrophysical Observatory photoheliogram data for 324 sunspots. The rotation amplitudes vary in thełinebreak 2–64° range (with maximum at 12–14°), and the periods around 0–20 days (with maximum atłinebreak 4–6 days). It could be concluded that sunspot rotations are rather inhomogeneous and asymmetric, but several types of sunspots are distinguished by their rotational parameters. During solar activity maximum, sunspot average rotation periods and amplitudes slightly increase. This can be affected by the increase of sunspot magnetic flux tube depth. So we can suppose that sunspot formation during solar activity is connected to a rise of magnetic tubes from deeper layers of the solar photosphere, strengthening the processes within the tube and causing variations in rotation. There is a linear relation between tilt-angle oscillation periods and amplitudes, showing higher amplitudes for large periods. The variations of those periods and especially amplitudes have a periodical shape for all types of sunspots and correlate well with the solar activity maxima with a phase delay of about 1–2 years.