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History of observation - History of observation Later it...

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History of observation Later it was found that not all (actually only 10% or so) quasars have strong radio emission (are 'radio-loud'). Hence the name 'QSO' (quasi-stellar object) is used (in addition to 'quasar') to refer to these objects, including the 'radio-loud' and the 'radio-quiet' classes. One great topic of debate during the 1960s was whether quasars were nearby objects or distant objects as implied by their redshift . It was suggested, for example, that the redshift of quasars was not due to the expansion of space but rather to light escaping a deep gravitational well . However a star of sufficient mass to form such a well would be unstable and in excess of the Hayashi limit . [16] Quasars also show ' forbidden ' spectral emission lines which were previously only seen in hot gaseous nebulae of low density, which would be too diffuse to both generate the observed power and fit within a deep gravitational well. [17] There were also serious concerns regarding the idea of cosmologically distant quasars. One strong argument against them was that
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