Related papers: Ionization correction factors for ionized nebulae
The iron depletion factors found in Galactic planetary nebulae (PNe) span over two orders of magnitude, suggesting that there are differences in the grain formation and destruction processes from object to object. We explore here the…
We demonstrate that by combining two robust theoretical quantum chemistry calculation techniques, stepwise ionization of C60 fullerene by UV and extreme UV photons can in principle occur up to a limit as high as q=+26 before coulomb…
As building blocks of dust, rocky planets, and even complex life, the chemical elements heavier than hydrogen (H) and helium (He) - called "metals" in astronomy - play an essential role in our Universe and its evolution. Up to Fe and Ni,…
I explore the effects of observational errors on nebular chemical abundances using a sample of 179 optical spectra of 42 planetary nebulae (PNe) observed by different authors. The spectra are analysed in a homogeneous way to derive physical…
A summary is given of planetary nebulae abundances from ISO measurements. It is shown that these nebulae show abundance gradients (with galactocentric distance), which in the case of neon, argon, sulfur and oxygen (with four exceptions) are…
Aim: To determine whether or not gas-phase chemical models with homogeneous and time-independent physical conditions explain the many observed molecular abundances in astrophysical sources, it is crucial to estimate the uncertainties in the…
The modeling of galaxy formation and reionization, two central issues of modern cosmology, relies on the accurate follow-up of the intergalactic medium (IGM). Unfortunately, owing to the complex nature of this medium, the differential…
Integral field spectroscopy (IFS) offers a distinct advantage for studying extended sources by enabling spatially resolved emission maps for several emission lines without the need for specific filters. This study conducts a detailed…
The analysis of the elemental abundances in galaxy clusters offers valuable insights into the formation and evolution of galaxies. In this study, we explore the chemical enrichment of the intergalactic medium (ICM) in the Ophiuchus cluster…
We investigate numerically the hydrodynamic instability of an ionization front (IF) accelerating into a molecular cloud, with imposed initial perturbations of different amplitudes. When the initial amplitude is small, the imposed…
We present some results of an on-going project aimed at studying a sample of Galactic HII regions ionized by a single massive star to test the predictions of modern generation stellar atmosphere codes in the H Lyman continuum. The…
Using a sample of 28 HII regions from the literature with measured temperature inhomogeneity parameter, t^2, we present a statistical correction to the chemical abundances determined with the Te(4363/5007) method. We used the t^2 values to…
The determination of accurate chemical abundances of planetary nebulae (PN) in different galaxies allows us to obtain important constraints of chemical evolution models for these systems. We have a long term program to derive abundances in…
Aims. We calculate the plasma environment effects on the ionization potentials (IPs) and K-thresholds used in the modeling of K lines for all the ions belonging to the isonuclear sequences of abundant elements apart from oxygen and iron,…
It is well-known that photoionization is the major mechanism powering nebulae emission-lines. For about 30 years, numerical simulations using photoionization codes have been employed to analyze HII regions, planetary nebulae and active…
While the chemical abudances observed in bright planetary nebulae in local spiral galaxies are less varied than their counterparts in dwarfs, they provide new insight. Their helium abundances are typically enriched by less than 50\%…
Precise determinations of the chemical composition in early B-type stars consitute fundamental observational constraints on stellar and galactochemical evolution. Carbon is one of the most abundant metals in the Universe but analyses in…
Ueta & Otsuka (2021) proposed a method, named as the "Proper Plasma Analysis Practice", to analyze spectroscopic data of ionized nebulae. The method is based on a coherent and simultaneous determination of the reddening correction and…
The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate a large…
Aims. The main objective of this article is to provide a simple physical framework with permits a quantitative comparison of measurements of the temperature fluctuations in the ionized interstellar medium with possible mechanisms which can…