We present new high-resolution observations of the central region in the late-type spiral galaxy M100 (NGC 4321) supplemented by three-dimensional numerical modeling of stellar and gas dynamics, including star formation (SF). Near-infrared imaging has revealed a small bulge of 4" effective diameter; a 60" radial length stellar bar of moderate

The Century Survey is a photometric survey strip from which we select blue stars to probe the Milky Way halo. We obtain S/N=30 spectra for every star with (V-R)

We present new CCD narrowband images and spatially resolved intermediate-dispersion spectroscopy of the hydrogen-poor nebulae A30 and A58. These data have allowed us to obtain information on the physical properties and chemical abundances of the inner knots and outer envelopes of A30 and A58 as a basis for the discussion of their implications in

The abundance gradient in M 33 is studied on the basis of IPCS and CCD data on emission lines in selected H II regions, using O II, O III, S II, and S III in the wavelength range 3700-9600 A to refine the oxygen abundances in the inner parts as well as to study the behavior of S/O. Spatially resolved observations in each H II region permit the

Aims. The aim of this work is to shed some light on the problem of the formation of carbon stars of R-type from a detailed study of their chemical composition. Methods: We use high-resolution and high signal-to-noise optical spectra of 23 R-type stars (both early- and late-types) selected from the Hipparcos catalogue. The chemical analysis is made

Spectroscopic studies of stars with and without planetary systems have concluded that planet hosts are more metal-rich. This enrichment is also seen in the other chemical elements studied and is likely to be primordial in nature. Interesting trends of different chemical elements begin to appear as the number of extrasolar planets continues to grow