Determining the state of the corona prior to CMEs is crucial to understanding and ultimately predicting solar eruptions. A common and compelling feature of CMEs is their three-part morphology, as seen in white-light observations of a bright expanding loop, followed by a relatively dark cavity, and finally a bright core associated with an erupting prominence/filament. This morphology is an impor...

Forbes & Lin derived simple equations to link the properties of magnetic reconnection in the corona to observed signatures of solar flares. We measured the photospheric magnetic fields and the flare ribbon separation speeds then applied these equations to derive two physical terms for the magnetic reconnection rates: the rate of magnetic flux change ’rec involved in magnetic reconnection in the...

It is shown that a generalized magneto–Bernoulli mechanism can effectively generate high velocity flows in the Solar chromosphere by transforming the plasma pressure energy into kinetic energy. It is found that at reasonable heights and for realistic plasma parameters, there is a precipitous pressure fall accompanied by a sharp amplification of the flow speed. Subject headings: Sun: atmosphere ...

A forward model is described in which we synthesize spectra from an ab-initio 3D MHD simulation of an outer stellar atmosphere, where the coronal heating is based on braiding of magnetic flux due to photospheric footpoint motions. We discuss the validity of assumptions such as ionization equilibrium and investigate the applicability of diagnostics like the differential emission measure inversio...

We point out the priority of our paper (Mahajan et al. 2001) over (Aschwanden et al. 2007) in introducing the term ”Formation and primary heating of the solar corona” working out explicit models (theory as well as simulation) for coronal structure formation and heating. On analyzing the (Aschwanden et al. 2007) scenario of coronal heating process (shifted to the chromospheric heating) we stress...

White-light observations of the solar corona show that there are two characteristic types of Coronal Mass Ejections (CMEs) in terms of speed-height profiles: so-called fast CMEs that attain high speeds low in the corona and slow CMEs that gradually accelerate from low initial speeds. Low and Zhang have recently proposed that fast and slow CMEs result from initial states with magnetic configurat...

Observations of type II radio bursts and energetic electron events indicate that shocks can form at 1Y3 solar radii and are responsible for the GeV nucleon 1 energies observed in ground level solar energetic particle (SEP) events. Here we provide the first study of the lower corona produced from 10 state-of-the-art models. In particular, we look to the Alfvén speed profiles as the criterion for...

We present the first observations of nonthermal decimetric burst emission of the Sun using the new 400 cm (74 MHz) system at the VLA. Our VLA observations were carried out in collaboration with the Large Angle Spectroscopic Coronagraph (LASCO) and the Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft. Full-disk observations at 400 and 91 cm w...

We use time series observations from the Solar and Heliospheric Observatory and Yohkoh spacecraft to study solar polar rays. Contrary to our expectations, we find that the rays are associated with active regions on the Sun and are not features of the polar coronal holes. They are extended, hot plasma structures formed in the active regions and projected onto the plane of the sky above the polar...

It is generally believed that the magnetic free energy accumulated in the corona serves as a main energy source for solar explosions such as coronal mass ejections (CMEs). In the framework of the flux rope catastrophe model for CMEs, the energy may be abruptly released either by an ideal magnetohydrodynamic (MHD) catastrophe, which belongs to a global magnetic topological instability of the sys...