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The Leo I Cloud: Secular nuclear evolution of NGC 3379, NGC 3384, and NGC 3368?

O. K. Sil'chenko·A. V. Moiseev·V. L. Afanasiev·V. H. Chavushyan·J. R. Valdes
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Abstract

The central regions of the three brightest members of the Leo I galaxy group -- NGC 3368, NGC 3379, and NGC 3384 -- are investigated by means of 2D spectroscopy. In all three galaxies we have found separate circumnuclear stellar and gaseous subsystems -- more probably, disks -- whose spatial orientations and spins are connected to the spatial orientation of the supergiant intergalactic HI ring reported previously by Schneider et al. (1983) and Schneider (1985, 1989). In NGC 3368 the global gaseous disk seems also to be inclined to the symmetry plane of the stellar body, being probably of external origin. Although the rather young mean stellar age and spatial orientations of the circumnuclear disks in NGC 3379, NGC 3384, and NGC 3368 could imply their recent formation from material of the intergalactic HI cloud, the time scale of these secondary formation events, of order 3 Gyr, does not support the collision scenario of Rood & Williams (1985), but is rather in line with the ideas of Schneider (1985, 1989) regarding tidal interactions of the galaxies with the HI cloud on timescales of the intergroup orbital motions.

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O. K. Sil'chenko, A. V. Moiseev, V. L. Afanasiev, V. H. Chavushyan, J. R. Valdes. 2003-03-19. The Leo I Cloud: Secular nuclear evolution of NGC 3379, NGC 3384, and NGC 3368?. https://doi.org/10.1086/375315

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