We present ultrahigh-resolution spectra for a set of nearby F-G-K stars on, or close to, the main sequence. The wavelength shifts of stellar lines relative to their laboratory wavelengths are measured for more than a thousand Fe I lines per star, finding a clear correlation with line depth. The observed patterns are interpreted as convective

When evolutionary synthesis models take into account the stochastic nature of the IMF together with the discrete number of stars in real stellar clusters, typical output turns to dispersion bands (where real data can be placed) instead of narrow lines. We present here a qualitative analysis of such dispersion in the SN rate, the kinetic energy and

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The effect of temperature fluctuations in the spectra of ionized nebulae was firstly explored by Peimbert (1967). Since then, the problem of their existence has remained an open question. In fact, there are observations and models that argue both in favor and against such fluctuations and these are reviewed in this paper. We also discuss the