An experiment is proposed to measure a critical part of the chromospheric flash spectrum during the eclipse which will occur November 13, 2012. The idea is to obtain rapid (30 Hz), high signal-to-noise spectrographic data at at least one chromospheric line, the calcium H line being the most desirable, at a spectral resolution of 15,000 or higher. A small telescope with a small exit pupil can be...

We present the X-ray observation of Vela shrapnel B with the XIS on board the Suzaku satellite. The shrapnel is one of several ejecta fragment-like features protruding beyond the primary blast wave shock front of the Vela supernova remnant. The spectrum of shrapnel B is well-represented by a singletemperature thin-thermal plasma in a non-equilibrium ionization state. The elemental abundances of...

The iron depletion level and the gas-phase iron abundance in the hot (∼ 106 K) interstellar medium (ISM) are critical to our understanding of its energy balance as well as the thermal sputtering, cooling, and heating processes of dust grains. Here we report on the first detection of the Fe XVII absorption line at 15.02 Å from the hot ISM in the spectrum of the low mass X-ray binary 4U 1820–303 ...

A table is presented that summarizes published absorption line measurements for the highand intermediate velocity clouds (HVCs and IVCs). New values are derived for N(H I) in the direction of observed probes, in order to arrive at reliable abundances and abundance limits (the H I data are described in Paper II). Distances to stellar probes are revisited and calculated consistently, in order to ...

We present measurements of the oxygen abundance of the Milky Way’s ISM by observing the K-shell X-ray photoionization edge towards galaxy clusters. This effect is most easily observed towards objects with galactic columns (nH) of a few times 1021 cm−2. We measure X-ray column densities towards 11 clusters and find that at high galactic columns above approximately 1021 cm−2 the X-ray columns are...