The study shows that there is a noticeable number of galaxies, attributed to the types E, S0, Sa and Sb (Table 1), which have relatively early spectral features (A and F spectral types) typical for the irregular and Sc galaxies. In most cases, central parts of these anomalous galaxies have considerable negative color residuals (Table 2). In addition, the color in these galaxies becomes redder, whereas color in the normal galaxies usually becomes bluer when removing from their centers. Besides this, the continuum in the short-wave part of the spectra of anomalous galaxies is relatively stronger. The examination of the data on the colors and spectra permits to conclude that central parts of the considered galaxies in addition to principal radiation (usually due to the type II stellar population) produce a strong continuum in violet and ultraviolet region of the spectrum. The investigation brings to the conclusion that this additional radiation, which probably represents a result of nuclear activity, has a non-stellar origin and seems to accompany the formation of new subsystems of stars going on in the same galaxy.
Communications of the Byurakan Astrophysical Observatory
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