相关论文: The effects of spatially distributed ionisation so…
Gas metallicity $Z$ and the related dust-to-gas ratio $f_\textrm{d}$ can influence the growth of HII regions via metal line cooling and UV absorption. We model these effects in star-forming regions containing massive stars. We compute…
We study the relation between the metallicities of ionised and atomic gas in star-forming galaxies at z=0-3 using the EAGLE cosmological, hydrodynamical simulations. This is done by constructing a dense grid of sightlines through the…
Star-forming galaxies with nebular HeII emission contain very energetic ionizing sources of radiation, which can be considered as analogs to the major contributors of the reionization of the Universe in early epochs. It is therefore of…
We analyze high signal-to-noise spectrophotometric observations acquired simultaneously with TWIN, a double-arm spectrograph, from 3400 to 10400 \AA of three star-forming regions in the HII galaxy SDSS J165712.75+321141.4. We have measured…
This is the second paper of a series reporting the results from the PopStar evolutionary synthesis models. Here we present synthetic emission line spectra of H{\sc ii} regions photoionized by young star clusters, for seven values of cluster…
We examine, from a theoretical viewpoint, how the physical parameters of HII regions are controlled in both normal galaxies and in starburst environments. These parameters are the HII region luminosity function, the time-dependent size, the…
The assumption of spherical symmetry is not justified for the vast majority of PNe. The interpretation of spatially-resolved observations cannot rely solely on the application of 1D codes, which may yield incorrect abundances determinations…
HII region electron temperatures are a critical ingredient in metallicity determinations and recent observations reveal systematic variations in the temperatures measured using different ions. We present electron temperatures ($T_e$)…
We extend our time-dependent hydrogen ionization simulations of diffuse ionized gas to include metals important for collisional cooling and diagnostic emission lines. The combination of heating from supernovae and time-dependent collisional…
Photoionization models of HII regions require as input a description of the ionizing SED and of the gas distribution, in terms of ionization parameter U and chemical abundances (e.g. O/H and N/O). A strong degeneracy exists between the…
The spectra of 413 star-forming (or HII) regions in M33 (NGC 598) were observed by using the multifiber spectrograph of Hectospec at the 6.5-m Multiple Mirror Telescope (MMT). By using this homogeneous spectra sample, we measured the…
We analyze the dynamical expansion of the HII region, photodissociation region, and the swept-up shell, solving the UV- and FUV-radiative transfer, the thermal and chemical processes in the time-dependent hydrodynamics code. Following our…
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…
Modelling galaxy formation in hydrodynamic simulations has increasingly adopted various radiative transfer methods to account for photoionization feedback from young massive stars. However, the evolution of HII regions around stars begins…
Context. The He i 1083 nm is a powerful diagnostic for inferring properties of the upper solar chromosphere, in particular for the magnetic field. The basic formation of the line in one-dimensional models is well understood, but the…
Three-dimensional (3D) radiative hydrodynamic model atmospheres of metal-poor late-type stars are characterized by cooler upper photospheric layers than their 1D counterparts. This property of 3D models can dramatically affect elemental…
The study of photoionized environments is fundamental to many astrophysical problems. Up to the present most photoionization codes have numerically solved the equations of radiative transfer by making the extreme simplifying assumption of…
Understanding the complex ionization structure and chemical composition of \hii\ regions poses a significant challenge in astrophysics. The abundance discrepancy problem, characterized by inconsistencies between abundances derived from…
The ionization feedback from HII regions modifies the properties of high-mass starless clumps (HMSCs, of several hundred to a few thousand solar masses with a size of ~0.1-1 pc), such as temperature and turbulence, on the clump scale. The…
When analysing HII regions, a possible source of systematic error on empirically derived physical quantities is the limited size of the slit used for the observations. A grid of photoionization models was built through the Aangaba code…