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Astronomy and Astrophysics for the 1980's, Volume 2 Reports of the Panels (1983) / Chapter Skim
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V. Extreme-Ultraviolet Astronomy
Pages 38-42

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 38...
... This very limited survey revealed five discrete extrasolar sources of E W radiation and demonstrated the feasibility and potential scientific importance of E W astronomy. In addition, various observations have led to the conclusion that the average density of interstellar matter is less than had been previously assumed and is highly nonuniform.
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From page 39...
... have provided detailed information about the temperatures, densities, and velocity structures in the chromospheres and lower transition regions of stellar atmospheres where the temperatures range up to 105 K In upper transition regions and coronas, where the temperatures are in the range from 105 to 107 R
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From page 40...
... white dwarfs are absent. Soft x-ray observations of a number of cataclysmic variables have shown that their spectra rise sharply with decreasing energy near 0.1 keV, while far- W observations by IUE have shown that the ultraviolet flux of many cataclysmic variables and magnetic white dwarfs rises with increasing energy near 0.01 keV.
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From page 41...
... 4. The Interstellar Medium Various observations lead to the conclusion that the interstellar medium is very inhomogeneous in temperature and density, with conditions ranging from cold dense clouds near absolute zero to ratified intercloud gas with temperatures up to a million kelvins.
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From page 42...
... Since the spectrum of this gas is dominated by line emission, high-resolution spectral observations will be a rich source of information on the temperature and composition of the gas. Intervening neutral hydrogen imposes a low-energy cutoff on the spectrum of this background radiation at wavelengths determined by the amount of absorbing material along the line of sight.
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Key Terms

  • white dwarfs
  • unique information
  • stellar atmospheres
  • transition regions
  • degenerate dwarf

  • cataclysmic variables
  • various observations
  • stellar evolution
  • stellar spectra
  • provide unique

  • ultraviolet explorer
  • white dwarf
  • magnetic field
  • cataclysmic variable
  • energy near

  • magnetic white
  • decreasing energy
  • neutral hydrogen
  • explorer program
  • conditions occur

  • gas produces
  • five discrete
  • polarimetric measurements
  • ultraviolet flux
  • sensitive probe

  • dwarfs rises
  • immediate progenitors
  • stars radiate
  • interstellar gas
  • velocity structures


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