Abstract We report the discovery of highly ionized line emission from CIVλ1550Å, OIII] λ1663Å, and OVI/SiIV λ1400Å, observed by the Berkeley UVX experiment on Shuttle mission 61-C. The CIV and OIII] lines were detected in 4 out of 8 directions, and the OVI/SiIV in 2 directions. The CIV line intensity exhibits a definite anticorrelation with HI column density, and shows significant pole brightening (a factor of 5 at least). There is evidence that the gas is not isothermal. When compared to observed CIV absorption column densities, we derive intrinsic densities of .01–.05 cm−3, and pressure p/k=1000–8000 (T/10 sup 5 K) cm−3 K, assuming the gas has a scale height of 2 kpc. Much higher densities and pressures are indicated if the gas is local (100–200 pc), which would give pressures in violation of canonical limits. Finally, we show that photoionized models, which break down at high densities because of charge exchange with HI, are inconsistent with the observed densities.
Discovery of highly ionized line emission in the far ultraviolet
Advances in Space Research ; 6 , 2 ; 79
1986-01-01
1 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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