We calculate the timeand energy-dependent opacity of high-energy γ-rays attenuated by pairproduction interactions with accretion-flare photons that are scattered by gas and dust surrounding the nuclei of active galaxies. We show that the temporal behavior of the high-energy opacity cutoff can be used in conjunction with the time history of the accretion flare to determine the location of the γ-...

We present an XMM-Newton observation of the eclipsing binary Algol which contains an X-ray dark B8V primary and an X-ray bright K2IV secondary. The observation covered the optical secondary eclipse and captured an X-ray flare that was eclipsed by the B star. The EPIC and RGS spectra of Algol in its quiescent state are described by a two-temperature plasma model. The cool component has a tempera...

Sensitive radio observations of the 1997 September 24 EIT wave show its velocity to be 830 km s−1. The wave first appears a short distance from the flare site, and its trajectory projects back to the flare site at the peak of the impulsive phase. The radio spectrum appears to be consistent with optically thin coronal emission rather than chromospheric emission. The observed radio brightness tem...

We analyse the coronal elemental abundances during a small flare using Hinode/EIS observations. Compared to pre-flare abundances, we observed strong increase in abundance of Ca XIV 193.84 {\AA}, an emission line with low first ionisation potential (FIP < 10 eV), as quantified by ratio Ca/Ar flare. This is contrast unchanged Si X 258.38 {\AA}/S 264.23 {\AA}. propose two different mechanisms expl...