There is currently no explanation of why the corona has the temperature and density it has. We present a model which explains how the dynamics of magnetic reconnection regulates the conditions in the corona. A bifurcation in magnetic reconnection at a critical state enforces an upper bound on the coronal temperature for a given density. We present observational evidence from 107 flares in 37 su...

Time series observations at UV (Extreme Ultraviolet Imaging Telescope/Solar and Heliospheric Observatory) and X-ray (Soft X-Ray Telescope/Yohkoh) wavelengths reveal properties of the global solar corona that are not easily identiÐed in a single image. A median-Ðltering technique that rejects features varying with time is used to isolate background corona. The coronal hole boundaries, polar plum...

Magnetic fields play a dominant role in the atmospheres of the Sun and other Sun-like stars. Outside sunspot regions, the photosphere of the so-called quiet Sun contains myriads of small-scale magnetic concentrations, with strengths ranging from the detection limit of ∼1016 Mx up to ∼ Mx. The tireless motion of these magnetic 20 3 # 10 flux concentrations, along with the continual appearance an...

Cool stars such as our Sun are surrounded by a million degree hot outer atmosphere, the corona. For more than 60 years, the physical nature of the processes heating the corona to temperatures well in excess of those on the stellar surface have remained puzzling. Recent progress in observational techniques and numerical modeling now opens a new window to approach this problem. We present the fir...

A wide swath of North America was reminded during last summer’s eclipse that you can’t stare at the sun without protection. But to study the sun, space probes have to do much more than stare. They have to get extremely close to the sun’s unforgiving environs. Next year, two solar missions will do exactly that— traveling tens of millions of miles to study the sun’s outer atmosphere, its corona, ...

Solar magnetic tornadoes are known to be one of the mass and energy transport mechanisms from the lower solar atmosphere into the upper layers of the solar corona. A bright spiral structure with two arms is observed using high-cadence EUV images of 171, 193 and 304 Ǻ channels of Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) on 10th of July 2011 for three hours. ...

We employ a sequence of Doppler images obtained with the Coronal Multi-channel Polarimeter (CoMP) instrument to perform time-distance seismology of the solar corona. We construct the first k−ω diagrams of the region. These allow us to separate outward and inward propagating waves and estimate the spatial variation of the plane-of-sky projected phase speed, and the relative amount of outward and...

The heating of the solar corona and the puzzle of the slender high reaching magnetic loops seen in observations from the Transition Region And Coronal Explorer(TRACE) has been investigated through 3D numerical simulations, and found to be caused by the well observed plasma flows in the photosphere displacing the footpoints of magnetic loops in a nearly potential configuration. It is found that ...

It is shown that the connection of sufficiently fast flows with dynamical channels for particle escape in the Solar Corona is rather direct: it depends on their ability to deform (in specific cases to distort) the ambient magnetic field lines to temporarily stretch (shrink, destroy) the closed field lines so that the flow can escape the local region. Using a dissipative two–fluid code in which ...

The Sun’s corona is millions of degrees hotter than its 5,000 K photosphere. This heating enigma is typically addressed by invoking the deposition at coronal heights of non-thermal energy generated by the interplay between convection and magnetic field near the photosphere. However, it remains unclear how and where coronal heating occurs and how the corona is filled with hot plasma. We show tha...