The discovery of giant gravitational arcs and arclets in rich clusters of galaxies is one of the major events of the last decade in observational cosmology. High resolution imaging in subarcsecond seeing conditions of giant arcs gives information on [...]
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In the last decade, our understanding of early-type galaxies has greatly changed: from rather uninteresting oblate spheroids flattened by rotation to multicomponent stellar systems whose structure, formation mechanisms, and evolution, are far from [...] In Part II of this paper we comment on the modelling of the complex interactions which take place in cometary comae and tails between parent molecules, radicals, ions, dust grains and the solar electromagnetic and corpuscular radiation (Sect. 4), and [...] This paper traces the evolution of the biogenic elements H, C, N, O, P and S from their creation by cosmic nucleosynthesis to their inclusion in living systems on the surface of the Earth. Evidence for the presence of significant prebiotic molecules [...] Cosmic dust grains play an important role for the thermal, dynamical, and chemical structure of the interstellar medium. This is especially true for the star formation process and the late stages of stellar evolution. Dust grains determine the [...] Binary stars are the main source of fundamental data on stellar masses and radii (M, R). Considerable progress has been made in recent years in the quality and quantity of such data, and stellar masses and radii of high accuracy have led to a number [...] Mass loss is a very important phenomenon for stellar evolution. In the late stages of stars it becomes fairly high (up to 10-4 M?/yr) though with a much decreased expansion velocity (about 30 kms-1). It can also be variable, sporadic. Now, though the [...] From the early discovery in 1948 of X-rays from the Solar corona, X-ray spectroscopy has proven to be an invaluable tool in studying hot astrophysical and laboratory plasmas. Because the emission line spectra and continua from optically thin plasmas [...] In the solar neighborhood, approximately half of all intermediate mass main sequence stars with initially between 1 and about 5 M?become carbon stars with luminosities near 104 L? for typically less than 106 years. These high luminosity carbon stars [...] X-ray images and spectra of clusters of galaxies show strong evidence for cooling flows. In many clusters, the hot gas in the core is cooling at rates of ~ 100M?yr-1 and greater. Few traces of the cooled gas have been observed, but it probably forms [...] |
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