Related papers: Energy balance in two phase models for temperature…
The magnitude of the temperature fluctuations (t^2) required to explain the observed inconsistencies between metallicities inferred from recombination lines and from forbidden lines cannot be attained by steady-state equilibrium…
Aims: We investigate temperature fluctuations in H II regions in terms of a two-phase model, which assumes that the nebular gas consists of a hot and a cold phase. Methods: We derive general formulae for T([O III), the [O III] forbidden…
A present prevailing open problem planetary nebulae research, and photoionized gaseous nebulae research at large, is the systematic discrepancies in ionic abundances derived from recombination and collisionally excited lines in many H II…
A prevailing open problem in planetary nebulae research, and photoionized gaseous nebulae research at large, is the systematic discrepancies in electron temperatures and ionic abundances as derived from recombination and collisionally…
We quantify the energy radiated through all the collisionally excited lines in a photoionized nebula which is permeated by temperature fluctuations. We assume that these correspond to hot spots which are the results of an unknown heating…
We present a detailed model capable of explaining quantitatively the temperature fluctuations observed in luminous, large HII regions. The model is based on two assumptions which we justify on the basis of observations: that the major…
There is evidence for temperature fluctuations in Planetary Nebulae and in Galactic HII regions. If such fluctuations occur in the low-metallicity, extragalactic HII regions used to probe the primordial helium abundance, the derived 4He…
While collisionally excited lines in HII regions allow one to easily probe the chemical composition of the interstellar medium in galaxies, the possible presence of important temperature fluctuations casts some doubt on the derived…
The origin of the abundance discrepancy in nebulae is one of the key problems in the physics of photoionized nebulae. In this work we have analized a sample of Galactic and extragalactic H II regions where the abundance discrepancy have…
We discuss the role of the electron temperature in abundance determinations in ionized nebulae (planetary nebulae and giant HII regions). We show that, even when observations provide a direct estimate of Te, abundance determinations may…
HII regions, ionized nebulae where massive star formation has taken place, exhibit a wealth of emission lines that are the fundamental basis for estimating the chemical composition of the Universe. For more than 80 years, a discrepancy of…
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…
We study the temperature structure of the intergalactic medium (IGM) using a large cosmological N-body/SPH simulation. We employ a two-temperature model for the thermal evolution of the ionized gas, in which the relaxation process between…
The temperature of the low-density intergalactic medium is set by the balance between adiabatic cooling resulting from the expansion of the universe, and photo-heating by the UV-background. We have analysed the Lyman-alpha forest of eleven…
We present a high spatial resolution map of the columnar electron temperature (Tc) of a region to the south west of the Trapezium in the Orion Nebula. This map was derived from Hubble Space Telescope images that isolated the primary lines…
An analysis of the OIII and SIII temperatures measurements compiled by Perez-Montero et al. of emission line objects consisting of HII galaxies, giant extragalactic HII regions, Galactic HII regions and HII regions from the Magellanic…
When comparing nebular electron densities derived from collisionally excited lines (CELs) to those estimated using the emission measure, significant discrepancies are common. The standard solution is to view nebulae as aggregates of dense…
The temperatures of interstellar dust grains are analyzed using stochastic simulations, taking into account the grain composition and size and the discreteness of the photon flux. [...] The distribution of grain temperatures is calculated…
The non-equilibrium fluctuations of power flux in a fluidized granular media have been recently measured in an experiment [Phys. Rev. Lett. 92, 164301, 2004], which was announced to be a verification of the Fluctuation Relation (FR) by…
The existence and origin of large spatial temperature fluctuations in HII regions and planetary nebulae are assumed to explain the differences between the heavy element abundances inferred from collisionally excited and recombination lines,…