Related papers: The impact of strong recombination on temperature …
The origin of the abundance discrepancy is one of the key problems in the physics of photoionized nebula. In this work, we analize and discuss data for a sample of Galactic and extragalactic HII regions where this abundance discrepancy has…
(Abridged) Results from the first dedicated study of Galactic PNe by means of optical integral field spectroscopy with the VLT FLAMES Argus IFU are presented. Three typical Galactic-disk PNe have been mapped with the 11.5''x7.2'' Argus…
This chapter presents a review on the latest advances in the computation of physical conditions and chemical abundances of elements present in photoionized gas H II regions and planetary nebulae). The arrival of highly sensitive…
Fluorescent excitation of spectral lines is demonstrated as a function of temperature-luminosity and the distance of the emitting region from the central stars of planetary nebulae. The electron densities and temperatures are determined,…
A few results that indicate the presence of temperature variations in gaseous nebulae are reviewed. The evidence is based on: a) temperatures derived from different methods, and b) on comparisons of abundances predicted by models of…
The elemental abundances of ten planetary nebulae, derived with high accuracy including ISO and IUE spectra, are analysed with the aid of synthetic evolutionary models for the TP-AGB phase. Model prescriptions are varied until we achieve…
We present deep spectroscopy of planetary nebulae (PNe) that are associated with the substructures of the Andromeda Galaxy (M31). The spectra were obtained with the OSIRIS spectrograph on the 10.4 m GTC. Seven targets were selected for the…
We present spectroscopy of planetary nebulae in M32 and in the bulge of M31 that we obtained with the MOS spectrograph at the Canada-France-Hawaii Telescope. Our sample includes 30 planetary nebulae in M31 and 9 planetary nebulae in M32. We…
We present the results of a study aimed at determining the 12C/13C ratio in two samples of planetary nebulae (PNe) by means of millimeter wave observations of 12CO and 13CO. The first group includes six PNe which have been observed in the…
Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with…
Based on O II recombination lines we present a new calibration (called O II[RL]) of Pagel's O23 indicator to determine the O/H abundance ratio in extragalactic H II regions and emission line galaxies. The O II(RL) calibration produces O/H…
Accurate rates for energy-degenerate l-changing collisions are needed to determine cosmological abundances and recombination. There are now several competing theories for the treatment of this process, and it is not possible to test these…
In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances…
Planetary nebulae are the products of the evolution of low and intermediate mass stars. The chemical property studies of these objects give important information about the elemental abundances as He, O, Ne, Ar, S and their modifications…
In planetary nebulae, abundances of oxygen and other heavy elements derived from optical recombination lines are systematically higher than those derived from collisionally excited lines. We investigate the hypothesis that the destruction…
Plasma diagnostics are the bases of investigation into the physical and chemical properties of line-emitting gaseous systems. To perform plasma diagnostics properly, it is essential to correct the input spectrum for extinction properly.…
We have undertaken a large spectroscopic survey of over 80 planetary nebulae with the goal of providing a homogeneous spectroscopic database between 3600-9600 Angstroms, as well as a set of consistently determined abundances, especially for…
The spectroscopic evolution of Hen\,3-1357, the Stingray Nebula, is presented by analysing data from 1990 to 2021. High resolution data obtained in 2021 with South African Large Telescope High Resolution Spectrograph and in 2009 with…
We previously determined abundances of He, C, N, O, and Ne for a sample of planetary nebulae (PNe) representing a broad range in progenitor mass and metallicity, and we now compare them with theoretical predictions of PNe abundances from a…
We present integral field unit (IFU) spectroscopy and self-consistent photoionisation modelling for a sample of four southern Galactic planetary nebulae (PNe) with supposed weak emission-line (WEL) central stars. The Wide Field Spectrograph…