The average distance between this galaxy cluster and the Earth is 99 millionSecond gap(321 millionLight year）, of which 10 are the brightestspiral galaxyOfApparent magnitudeBetween 12 and 14 grades, amateur astronomers can see with telescopes with an aperture of more than 20 cm.In the middle, there are two hugeElliptical galaxy：NGC 4874andNGC 4889。This galaxy cluster is far away from thethe galaxyThe North Pole is only a few degrees.Most of the galaxies in the central part of the Backhair Cluster are hugeElliptical galaxy, and there are abundantDwarf galaxyAnd giant elliptical galaxies.
The galaxies in this group are all very hotIntergalactic gasShrouded in and radiated remarkableX-ray radiation。These free gases have also changedCosmic microwave background radiationOfmicrowavespectrum, this effect is calledSunyaev Zel'dovich effect。The mass of the gas between these galaxies is far greater than the total mass of the galaxies in this galaxy cluster.
Members of galaxy clusters
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Such a rich cluster of galaxies, usuallyElliptical galaxyandLenticular galaxyWith overwhelming majority, the youngerspiral galaxyOnly a few, and probably most, are scattered around the outer edge of the cluster.
Although many galaxies have been identified separately, the understanding of galaxy clusters was incomplete until the 1950s,Palomar Observatory Only after the beginning of rigorous research did astronomers of.
dark substance
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Backhair ClusterAbout 90% of the quality is considered to bedark substanceHowever, the distribution of dark matter in the whole group is very unnatural.
X-ray source
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Before 1966, it was reported that there was an X-ray diffusion source centered at 1300+28 in the direction of the Backhair Cluster.The X-ray source is composed ofSounding balloonIt was discovered, but the X-ray Astronomy Group of the US Naval Research Laboratory launched theSounding rocket, the X-ray source was not detected in flight.X-ray observation satelliteLibertyA strong X-ray source was found near the center of the cluster, and this source was labeled as X-1 of the constellation.
With RA1256 ± 2Dec28 ° 6 '± 12' (1950 minutes) as the center on the celestial sphere, within an area of 100 X 100 arc minutes, the Backhair Galaxy Cluster contains about 800 galaxies with brightness Lx=2.6 x 10ergs/s flux.The source is diffuse, about 45 'in size, which has led to a dispute about whether it is emitted by a single galaxy.The observation of Freedom pointed out that there is a 2500 electron volt radiation source whose intensity does not exceed~10 photon centimeters skeV, which is inconsistent with the earlier observation that the size is about 5 °, at 25000 electron volts, the intensity is~10 photon centimeters skeVat 25 keV, and a size of.
