Stellar X-ray and Radio Activities and Coronal Magnetic Field

Radio emission from exoplanets: the role of the stellar coronal density and magnetic field strength

Context. The search for radio emission from extra-solar planets has so far been unsuccessful. Much of the effort in modelling the predicted emission has been based on the analogy with the well-known emission from Jupiter. Unlike Jupiter, however, many of the targets of these radio searches are so close to their parent stars that they may well lie inside the stellar magnetosphere. Aims. For thes...

X-ray and Radio Emission from Colliding Stellar Winds

The collision of the hypersonic winds in early-type binaries produces shock heated gas, which radiates thermal X-ray emission, and relativistic electrons, which emit nonthermal radio emission. We review our current understanding of the emission in these spectral regions and discuss models which have been developed for the interpretation of this emission. Physical processes which affect the resu...

Coronal Magnetic Field Measurements

A long-standing solar problem has been to measure the coronal magnetic field. We believe it determines the coronal structure and dynamics from the upper chromosphere out into the heliospheric environment. It is only recently that Zeeman splitting observations of infrared coronal emission lines have been successfully used to deduce the coronal magnetic flux density. Here we extend this technique...

Reconstruction of Solar Coronal Linear Force-Free Magnetic Field

Coronal type III radio bursts and their X-ray flare and interplanetary type III counterparts

Context. Type III bursts and hard X-rays are both produced by flare energetic electron beams. The link between both emissions has been investigated in many previous studies, but no statistical studies have compared both coronal and interplanetary type III bursts with X-ray flares. Aims. Using events where the coronal radio emission above 100 MHz is exclusively from type III bursts, we revisited...