Titlebook: Galaxies and Cosmology; Françoise Combes,Patrick Boissé,Alain Blanchard Textbook 1995 Springer-Verlag Berlin Heidelberg 1995 Universe.acti

解冻

The Galactic Interstellar Medium,der of 1 particle per cm., 10 cm. in clouds of atomic hydrogen, and 1000 cm. in molecular clouds. Its temperature goes from 5 K in these latter regions up to 10. K in ionized regions heated by young stars. Hydrogen forms the bulk of the interstellar gas, helium around 25%. Other elements are present

粘

BADGE

Elliptical Galaxies, this deceptive simplicity and until the end of the 1970s believed that they had succeeded in giving a complete mathematical description of the structure of these galaxies. Ellipticals were then thought to be axially symmetric isothermal ensembles, increasingly flattened the more rapidly they rotate

INTER

Intrepid

Interactions between Galaxies,xies in effect group themselves in clusters, small groups, or pairs: far from being isolated systems they are formed and evolve in interaction with their environment and in particular with neighbouring galaxies.

青石板

Extragalactic Radio Sources,dio-emission maximum in the constellation Cygnus. It was the first detection of Cygnus A, one of the brightest of all extragalactic sources (that is, located outside our Galaxy) in the radio region. These observations, made at low frequencies (160 MHz) and with the aid of small receivers, gave only

angina-pectoris

Quasars and Other Active Nuclei, on account of their remarkably small angular size and were therefore particularly suitable for a search for an associated optical object. For 3C 48, optical exposures of the corresponding field indicated an object with a stellar appearance; its spectrum showed very strong emission lines that at fir

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