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|X-Ray and Radio Interactions in the Cores of Cooling Flow Clusters|
We present high-resolution ROSAT X-ray and radio observations of threecooling flow clusters containing steep-spectrum radio sources at theircores. All three systems exhibit strong signs of interaction between theradio plasma and the hot intracluster medium. Two clusters, A133 andA2626, show enhanced X-ray emission spatially coincident with the radiosource, whereas the third cluster, A2052, exhibits a large region ofX-ray excess surrounding much of the radio source. Usingthree-dimensional numerical simulations, we show that a perturbed jetpropagating through a cooling flow atmosphere can give rise to amorphousradio morphologies, particularly in the case where the jet was ``turnedoff'' and allowed to age passively. In addition, the simulated X-raysurface brightness produced both excesses and deficits as seenobservationally.
|A survey of the Pisces-Perseus supercluster. VI - The declination zone +15.5 deg to 21.5 deg|
New results are presented of Arecibo observations in the 21 cm line of765 galaxies with declinations between 15.5 deg and 21.5 deg, in thePisces-Perseus supercluster zone. If considered independently on theneighboring parts of sky, this region, to the South of the superclusterridge, shows significantly less evidence of structure on large scales inexcess of 30 Mpc, contrasting substantially with the characteristics ofthe declination zones immediately to the North.
|HEAO 1 observations of quiescent X-ray emission from flare stars|
The HEAO A-2 data were searched at the positions of the 70 known flarestars for evidence of X-ray emission. Thirteen of them appear to bedetected at the equal to or greater than 3 sigma level. Their X-rayluminosities in the 2-20 keV energy band are in the range 5 x 10 to the28th - 6 x 10 to the 29th ergs/s and L(x)/L(bal) approximately 0.0001 to0.01. There were no detectable X-ray flare events during the time ofHEAO 1 observations. This detection, therefore, refers to the quiescentstate X-ray emission from the coronae of these stars. It appears thatintense coronae belonging to fairly active flare stars are beingobserved. X-ray variability over periods of 6 months was observed forseveral of them.
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