Related papers: Planetary Nebulae in the Magellanic Clouds: Probin…
We compare the populations of Red Giant stars and Planetary Nebulae in the Galactic Bulge, in the light of recent determinations of their abundances patterns. We find both populations to be compatible. From the planetary nebulae, we find…
The past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field,…
The goal of this article is to summarize the current state of play in the field of radio pulsar statistics. Simply put, from the observed sample of objects from a variety of surveys with different telescopes, we wish to infer the properties…
In view of their nature, planetary nebulae have very short lifetimes, and the chemical abundances derived so far have a natural bias favoring younger objects. In this work, we report physical parameters and abundances for a sample of old…
New observations and derived chemical abundances are reported for a sample of 57 bulge planetary nebulae (PN). Together with our previous results, a total of over a hundred objects have been analyzed, which constitute one of the largest…
A historical perspective on the study of asymmetries in planetary nebulae (PNs) is presented. We also describe our ongoing work in high resolution spectroscopy of planetaries, and discuss some likely future directions for the study of…
Although there are many more stellar population studies of elliptical and lenticular galaxies, studies of spiral galaxies are catching up, due to higher signal to noise data on one hand, and better analysis methods on the other. Here I…
We review the possible mechanisms for the generation of cosmological magnetic fields, discuss their evolution in an expanding Universe filled with the cosmic plasma and provide a critical review of the literature on the subject. We put…
Recent work on globular cluster systems in dwarf galaxies outside the Local Group is reviewed. Recent large imaging surveys with the Hubble Space Telescope and follow-up spectroscopy with 8-m class telescopes now allow us to compare the…
This review is focussed on the outer halos of elliptical galaxies. Its emphasis is on (i) planetary nebulae as test particles to trace the stellar kinematics at large radii, (ii) the observed angular momentum in elliptical galaxy halos and…
After a recall of fundamental concepts used in galactic dynamics, we review observational facts as well as results of orbit theory and numerical simulations which suggest long-term evolution of galaxies. Dynamical interactions between…
Why 80% of planetary nebulae are not spherical is not yet understood. The Binary Hypothesis states that a companion to the progenitor of the central star of a planetary nebula is required to shape the nebula and even for a planetary nebula…
A revival over the past two decades in planetary nebula (PN) morphological studies springs from a combination of factors, including the advent of wide-area, high dynamic range detectors; the growing archives of high resolution images from…
Nearly 50 years ago, in the proceedings of the first IAU symposium on planetary nebulae, Lawrence H. Aller and Stanley J. Czyzak said that "the problem of determination of the chemical compositions of planetary and other gaseous nebulae…
Context: In recent years mid- and far infrared spectra of planetary nebulae have been analysed and lead to more accurate abundances. It may be expected that these better abundances lead to a better understanding of the evolution of these…
This paper summarizes a project designed to study abundances in a sample of planetary nebulae representing a broad range in progenitor mass and metallicity. We collect abundances of C, N, and O determined for the entire sample and compare…
We observed five central stars of planetary nebulae (CSPN) in the Large Magellanic Cloud (LMC) and three in the Small Magellanic Cloud (SMC) with the Far Ultraviolet Spectroscopic Explorer (FUSE), in the range 905-1187 Ang. We performed a…
I discuss the development and resolution of the solar neutrino problem, as well as opportunities now open to us to extend our knowledge of main-sequence stellar evolution and neutrino astrophysics.
Planetary nebulae (PNe) are essential tracers of the kinematics of the diffuse halo and intracluster light where stellar spectroscopy is unfeasible, due to their strong emission lines. However, that is not all they can reveal about the…
Hydrodynamical (HD) simulations played an important role in understanding the dynamics and shaping of Planetary Nebulae (PNe) in the past century. However, HD solutions are just a first order approach. The new millennium arrives with the…