相关论文: Resonant temperature fluctuations in nebulae ioniz…

It is argued that an important fraction of PNe present large temperature variations that are not due to observational errors nor to incomplete atomic physics. Seven possible causes for these variations are reviewed, one of them is presented…

The current report presents the work to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination…

This paper continues our study of the behaviour of near infrared helium recombination lines in planetary nebula. We find that the 1.7007um 4^3D-3^3P HeI line is a good measure of the HeI recombination rate, since it varies smoothly with the…

We have obtained medium-resolution, deep optical long-slit spectra of the bulge planetary nebula (PN) M 2-24. The spectrum covers the wavelength range from 3610--7330 A. Over two hundred emission lines have been detected. The spectra show a…

X-ray emitting diffuse nebulae around hot stars are observed to have soft-band temperatures in the narrow range [1-3]$\times10^{6}$ K, independent of the stellar wind parameters and the evolutionary stage of the central star. We discuss the…

Evidence of small-scale condensations in the magnetic molecular clouds has been accumulating over the past decades through radio and optical/ultraviolet observations. The origin and shape of these small-scale condensations is a disputable…

We have carried out optical spectroscopic measurements of emission lines for a sample of Galactic planetary nebulae with Wolf-Rayet (WR) stars and weak emission-line stars (wels). The plasma diagnostics and elemental abundance analysis have…

We consider the effects of inhomogeneous reionization on the distribution of galaxies at high redshifts. Modulation of the formation process of the ionizing sources by large scale density modes makes reionization inhomogeneous and…

We present literature on abundance determinations in planetary nebulae (PN) as well as public tools that can be used to derive them. Concerning direct methods to derive abundances we discuss in some depth such issues as reddening…

We present integral field unit spectroscopic observations of southern Galactic planetary nebulae (PNe), IC 2501, Hen 2-7, and PB4. The goal of studying these objects together is that, although they have roughly similar intermediate…

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…

We present a combined analysis of rest-frame far-UV (1000-2000 A) and rest-frame optical (3600-7000 A) composite spectra formed from very deep observations of a sample of 30 star-forming galaxies with z=2.4+/-0.1, selected to be…

In this contribution, I will briefly review the development of the theory of photoionized gaseous nebulae, highlighting some of the key events. I will then present some recent developments of deep spectroscopy of planetary nebulae (PNe) and…

Though the small-scale, low-ionization knots, filaments and jets (LISs) of planetary nebulae (PNe) are known for ~30yr, some of their observational properties are not well established. In consequence our ability to include them in the wider…

Recent weak emission-line long-slit surveys and modelling studies of PNe have convincingly argued in favour of the existence of an unknown component in the planetary nebula plasma consisting of cold, hydrogen-deficient gas, as an…

We present IFU observations of six emission-line nebulae that surround the central galaxy of cool core clusters. Qualitatively similar nebulae are observed in cool core clusters even when the dynamics and possibly formation and excitation…

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…

Theory predicts that the temperature of the X-ray-emitting gas ($\sim$10$^{6}$ K) detected from planetary nebulae (PNe) is a consequence of mixing or thermal conduction when in contact with the ionized outer rim ($\sim$10$^{4}$ K). Gas at…

We study the hypothesis of high metallicity clumps being responsible for the abundance discrepancy found in planetary nebulae between the values obtained from recombination and collisionaly excited lines. We generate grids of…

We analysed the planetary nebula Hen 2-260 using optical spectroscopy and photometry. We compared our observations with the data from literature to search for evolutionary changes. The nebular line fluxes were modelled with the Cloudy…