Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present a new method for quantifying such structures using density-sensitive extreme ultraviolet line intensities to derive a density irregularity parameter, a rela...

Based on the conjectured existence of primary solar emanations (plasma flows from the solar surface), a model for the Origin of the Fast Solar Wind, and the creation and heating of the coronal structures is developed. Preliminary results reproduce many of the salient observational features.

We present a measurement of the abundance of Fe relative to H in the solar corona using a technique which diiers from previous spectroscopic and solar wind measurements. Our method combines EUV line data from the CDS spectrometer on SOHO with thermal bremsstrahlung radio data from the VLA. The coronal Fe abundance is derived by equating the thermal bremsstrahlung radio emission calculated from ...

The abundance of helium in the Sun's interior is estimated by the method of`model-oriented' helioseismic inversion of solar oscillation frequencies. In this method, the equations of state and thermal balance are used in addition to the hydrostatic equation. By inverting the observed p-mode frequencies, direct evidence for gravitational settling of helium has been obtained. However, the helium s...

It is generally acknowledged that CMEs, especially the faster ones, must deceleration somewhere between the high corona and interplanetary medium. However, the detailed characteristics and spatial region over which this deceleration occurs is still largely unknown. Simultaneous radio and white-light observations can provide information on the speed profiles of the CME or CME/shock in the high c...

The slow solar wind belt in the quiet corona, observed with Metis coronagraph on board Solar Orbiter May 15, 2020, during activity minimum of cycle 24, a field view extending from 3.8 $R_\odot$ to 7.0 $R_\odot$, is formed by and dense stream running along coronal current sheet, accelerating radial direction reaching at 6.8 speed within 150 km s$^{-1}$ 190 s$^{-1}$, depending assumptions velocit...

[1] We present a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD) model describing the time-dependent expulsion of a coronal mass ejection (CME) from the solar corona propagating to 1 astronomical unit (AU). The simulations are performed using the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. We begin by developing a global steady-state model of the corona...

The existence of the Sun's hot atmosphere and the solar wind acceleration continues to be an outstanding problem in solar-astrophysics. Although magnetohydrodynamic (MHD) modes and dissipation of magnetic energy contribute to heating and the mass cycle of the solar atmosphere, yet direct evidence of such processes often generates debate. Ground-based 1-m Swedish Solar Telescope (SST)/CRISP, Hα ...

We show that the coronal heating and the fast solar wind acceleration in the coronal holes are natural consequence of the footpoint fluctuations of the magnetic fields at the photosphere, by performing one-dimensional magnetohydrodynamical simulation with radiative cooling and thermal conduction. We initially set up a static open flux tube with temperature 10K rooted at the photosphere. We impo...