Quasars
(Quasi-stellar Objects)
QSO
Star
Strange “stars” were found with spectral lines that turned out to be normal lines but at extremely high red Doppler shifts. The expansion of the Universe means that they must be VERY far away, yet they were not too faint.
Even Seyfert nuclei would not be bright enough. The energy output would have to be up to 100’s of times that from a whole normal galaxy, but the source was point-like.