Search

In core-collapse supernovae, titanium-44 ((44)Ti) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed compact object. As such, it provides a direct probe of the supernova engine. Observations of supernova 1987A (SN1987A) have resolved the 67.87- and 78.32-kilo-electron volt emission lines from decay of (44)Ti produced in the supernova explosion. These lines are narrow and redshifted with a Doppler velocity of ~700 kilometers per second, direct evidence of large-scale asymmetry in the explosion.

Two clusters of galaxies have been observed with EXOSAT to map the distribution of cool gas. For A1367 we have detected the two brightest sources found by EINSTEIN. We confirm the identification of a X-ray source with a blue object near NGC3842. By comparing the EXOSAT and the EINSTEIN count rates we can state, either that the source is variable, or that the HI column density is low and the spectrum is either a power-law with a spectral index > 1.5 or thermal with a temperature below 6x106K. For A1060 we confirm the classification from optical data of NGC3311 as the dominant galaxy but we find no evidence for a central source as inferred from the EINSTEIN data. We derive an accretion rate of ~10Mo/yr.

The binary system Capella has been observed on 1979 March 15 and on 1980 March 15-17, with the objective grating spectrometer on board the Einstein Observatory. The spectrum measured with the 1000 1/mm grating covers the range 5-30 A with a resolution less than 1 A. The spectra show evidence for a bimodal temperature distribution of emission measure in an optically thin plasma with one component about 5,000,000 K and the other one about 10,000,000 K. Spectral features can be identified with line emissions from O VIII, Fe XVII, Fe XVIII, Fe XXIV, and Ne X ions. Good spectral fits have been obtained assuming standard cosmic abundances. The data are interpreted in terms of emission from hot static coronal loops rather similar to the magnetic arch structures found on the sun. It is shown that the conditions for such a model can exist on Capella. Typical values of loop base pressure and half-length are derived for both temperature components and discussed in relation to UV observations.