Black holes at the centers of the galaxies grow mainly by the processes of accretion, mergers, and consumption of stars. In the case of gas accretion with cooling sources, the flow is momentum driven, after which the black ...

Context. Weak G -band (wGb) stars are a very peculiar class of red giants; th ey are almost devoided of carbon and often present mild lithium enrichment. Desp ite their very puzzling abundance pa tterns, very few ...