Models of the origin of spheroidal stellar systems, or cluster formation scenarios, need to account for empirical correlations both between scale and velocity dispersion σ and between luminosity and σ found in star-forming regions and relaxed spheroidal stellar systems. The model here proposed accounts for both correlations if the stellar system

The GJ 436 system contains a transiting planet GJ 436 b which is a hot analogue of Neptune on an eccentric orbit. Recently, two additional transiting sub-Earth planets have been postulated in the literature. We observed three transits of GJ 436 b over the course of three years using two-meter class telescopes, each with a photometric precision

In this contribution we examine the problem of inferring ages and initial cluster masses from synthesis models at the limit of low-mass clusters ( M≤ a few ×104 M⊙). We show that it is not possible to apply directly synthesis models using standard methods to such clusters, since the basic hypothesis implicit in the models (a fixed proportionality

The suitability of the Eddington approximation as a theoretical framework for the study of the possibility of a k-like overstability mechanism as the driving force of solar modes of oscillation is assessed. A theoretical description of the interaction between the hydrodynamics of the motion and the radiative energy transport is needed. It is found

Recent studies have claimed that the Hubble sequence of late-type spirals, and spirals in general, is scale-free. Within the photometric data used in these works, a trend exists between morphological type and bulge profile shape such that late-type spiral bulges are described by an exponential luminosity profile, where-as the early-type spiral

Assuming that photoionization is the self-limiting process for continued star formation, we estimate the maximum number of massive (OB) stars that can form within a molecular cloud. The most efficient cloud destruction mechanism in the early stages of H II region evolution is the evaporation of the cloud by stars located near the cloud boundary