Related papers: The effects of spatially distributed ionisation so…
We present a detailed comparison of the ionizing spectral energy distributions (SEDs) predicted by four modern stellar atmosphere codes, TLUSTY, CMFGEN, WMbasic, and FASTWIND. We consider three sets of stellar parameters representing a late…
We investigate how HII region temperature structure assumptions affect "direct-method" spatially-resolved metallicity observations using multispecies auroral lines in a galaxy from the SAMI Galaxy Survey. SAMI609396B, at redshift $z=0.018$,…
With the advent of Integral Field Units (IFUs), surveys can now measure metallicities across the discs of nearby galaxies at scales $\lesssim 100~$ pc. At such small scales, many of these regions contain too few stars to fully sample all…
Determining the properties of solar-like oscillating stars can be subject to many biases. A particularly important example is the helium-mass degeneracy, where the uncertainties regarding the internal physics can cause a poor determination…
The emission line ratios [OIII]5007/H-beta and [NII]6584/H-alpha have been adopted as an empirical way to distinguish between the fundamentally different mechanisms of ionization in emission-line galaxies. However, detailed interpretation…
In the present paper, we aim to constrain the properties of the ionisation region in a star from the oscillation frequency variation (a so-called glitch) caused by rapid structural variations in this very region. In particular, we seek to…
Massive stars and their associated ionized (HII) regions could play a key role in the formation and evolution of filaments that host star formation. However, the properties of filaments that interact with H regions are still poorly known.…
(Abridged) We present fine structure and recombination lines observations of the ionized gas toward a sample of 18 sources located within 300 pc of the center of the Galaxy (GC). The fine structure lines from [NII] and [SIII] have been…
Observing giant HII regions at fine spatial scales uncovers detailed structures and reveals variations in ionization, abundance, and dynamical properties of ionized gas and the effect of stellar feedback. Using emission line data of M33…
We investigate, whether the alleged failure of standard photoionization codes of the Diffuse Ionized Gas (DIG) is simply caused by geometrical effects and the insufficient treatment of the radiative transfer. Standard photoionization models…
Spectra of high-metallicity (12+log(O/H) > 8.2) HII regions where oxygen auroral lines are measurable in both the O+ and O++ zones, have been extracted from the Data Release 6 of the Sloan Digital Sky Survey (SDSS). Our final sample…
We use the optical integral field observations with Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope, together with CLOUDY photoionization models to study ionization structure and physical conditions of two luminous HII…
We study the physical and chemical properties of a sample of HII regions located at RG >11 kpc and present the radial distribution of abundances towards the Galaxy anticentre. We carried out optical spectroscopic observations of nine HII…
The accepted explanation of the observed dichotomy of two orders of magnitude between in situ measurements of electron density in HII regions, derived from emission line ratios, and average measurements based on integrated emission measure,…
HII region heavy-element abundances throughout the Galactic disk provide important constraints to theories of the formation and evolution of the Milky Way. In LTE, radio recombination line (RRL) and free-free continuum emission are accurate…
In cold dark matter cosmological models, the first stars to form are believed to do so within small protogalaxies. We wish to understand how the evolution of these early protogalaxies changes once the gas forming them has been enriched with…
We have computed a series of realistic and self-consistent models that have been shown to be able to reproduce the emitted spectra of HII galaxies in a star bursting scenario (Martin-Majon et al. 2008). Our models combine different codes of…
We simulate a self-gravitating, turbulent cloud of 1000 Msol with photoionization and radiation pressure feedback from a 34 Msol star. We use a detailed Monte Carlo radiative transfer scheme alongside the hydrodynamics to compute…
Given the rarity of young O star candidates, compact HII regions embedded in dense molecular cores continue to serve as potential sites to peer into the details of high-mass star formation. To uncover the ionizing sources of the most…
Observations of nearby galaxies have firmly established, over a broad range of galactic environments and metallicities, that star formation occurs exclusively in the molecular phase of the interstellar medium (ISM). Theoretical models show…