We report the detection of the line of Si ix using the McMath-Pierce telescope on Kitt Peak. 2 2 3 2s 2p P1 r 0 Observations were made of the solar disk and at various heights above the limb between 2002 May 13 and 17, under nonideal sky conditions, using the 13.5 m vertical spectrograph and an InSb single-diode detector. We report a new rest wavelength for the line and discuss its potential us...

A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to trace data, obtained using the 171Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. (1999). However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a ...

The frequent occurrence of hard X-ray emission from the top of Ñaring loops was one of the discoveries by the Hard X-Ray Telescope on board the Japanese Yohkoh satellite. In this paper we take a Ñare current-sheet geometry and show how the combined e†ect of magnetic Ðeld convergence and pitchangle scattering of nonthermal electrons injected at the top of the loop results in the generation of a ...

Superflares are large explosive events on stellar surfaces one to six orders-of-magnitude larger than the largest flares observed on the Sun throughout the space age. Due to the huge amount of energy released in these superflares, it has been speculated if the underlying mechanism is the same as for solar flares, which are caused by magnetic reconnection in the solar corona. Here, we analyse ob...

We present conspicuous activities of plasma ejections along a light bridge of a stable and mature sunspot in NOAA 8971 on 2000 May 02. We found the ejections both in the Hα (10 K) images obtained with the Domeless Solar Telescope (DST) at Hida Observatory, and in the 171 Å (Fe ix/x, ∼106 K) images obtained with the Transition Region and Coronal Explorer (TRACE). Main characteristics of the ejec...

We present the Ðrst model of resonant heating of coronal loops that incorporates the dependence of the loop density on the heating rate. By adopting the quasi-static equilibrium scaling law o P Q5@7, where o is the density and Q is the volumetric heating rate, we are able to approximate the well-known phenomena of chromospheric evaporation and chromospheric condensation, which regulate the coro...

We present the first comparison between radio images of high–energy electrons accelerated by a solar flare and images of hard X–rays produced by the same electrons at photon energies above 100 keV. The radio and hard X–ray light curves match each other well and both light curves and spectra are quantitatively consistent with an origin in a single population of nonthermal electrons with a power ...

We address the statistical modeling of solar images provided by the Extreme ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SoHO, a joint ESA/NASA mission). We focus in particular on the less structured regions, the “Quiet Sun”. We first review on a brief historical viewpoint on multifractal processes for physical modeling. Then we present a multifractal anal...

We present a method for deriving a twoÈthermal-component approximation to the di†erential emission measure distribution of plasma in the SunÏs corona in the temperature range to which the ExtremeUltraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) spacecraft is sensitive. EIT takes high-resolution full-disk coronal images in three of its four optimized channels b...

The solar corona, anomalously hot outer atmosphere of the Sun, is traditionally described by magnetohydrodynamic, fluid-like approach. Here we review some recent developments when, instead, a full kinetic description is used. It is shown that some of the main unsolved problems of solar physics, such as coronal heating and solar flare particle acceleration can be viewed in a new light when the s...