Related papers: Nebular abundance gradient in the Cartwheel galaxy…

The validity of oxygen and nitrogen abundances derived from the global emission-line spectra of galaxies via the P-method has been investigated using a collection of published spectra of individual HII regions in irregular and spiral…

A thorough critical literature survey has been carried out for reliable measurements of oxygen and neon abundances of planetary nebulae (PNe) and HII regions. By contrasting the results of PNe and of HII regions, we aim to address the…

We determine the gas-phase oxygen abundance for a sample of 695 galaxies and H II regions with reliable detections of [O III]4363, using the temperature-sensitive Te method. Our aims are to estimate the validity of empirical methods such as…

We derive the Mg/H ratio in the Orion nebula and in 30 Doradus. We also derive the O/H and the Fe/O ratios in the extremely metal poor galaxy SBS 0335-052. We estimate the dust depletions of Mg, Si, and Fe in Galactic and extragalactic H II…

I present deep spectroscopy of four HII regions in the inner, metal-rich zone of the spiral galaxy M101 obtained with the LRIS spectrograph at the Keck telescope. From the analysis of the collisionally excited lines in two of the target HII…

Spectra of 34 H II regions in the late-type galaxies NGC1087, NGC2967, NGC3023, NGC4030, NGC4123, and NGC4517A were observed with the South African Large Telescope (SALT). In all 34 H II regions, oxygen abundances were determined through…

We present results of long-slit spectroscopy in several positions of the Orion nebula. Our goal is to study the spatial distribution of a large number of nebular quantities, including line fluxes, physical conditions and ionic abundances at…

We present spectroscopy of planetary nebulae in M32 and in the bulge of M31 that we obtained with the MOS spectrograph at the Canada-France-Hawaii Telescope. Our sample includes 30 planetary nebulae in M31 and 9 planetary nebulae in M32. We…

Gas infall and outflow are critical for determining the star formation rate and chemical evolution of galaxies but direct measurements of gas flows are diffcult to make. Young massive stars and HII regions in the halos of galaxies are…

Using data from the LAMOST Medium-Resolution Spectroscopic Survey of Nebulae, we create a sample of 17,821 diffuse ionized gas (DIG) spectra in the anti-center region of the Milky Way, by excluding fibers in the directions of H II regions…

The CHemical Abundances of Spirals (CHAOS) project leverages the combined power of the Large Binocular Telescope (LBT) with the broad spectral range and sensitivity of the Multi Object Double Spectrograph (MODS) to measure "direct"…

We have obtained spectroscopic observations from 3600 Angstrom to 9200 Angstrom with FORS at the Very Large Telescope for approximately 70 H II regions located in the spiral galaxies NGC 1232, NGC 1365, NGC 2903, NGC 2997 and NGC 5236.…

Highly ionized species such as C IV, N V, and O VI, are commonly observed in diffuse gas in various places in the universe, such as in our Galaxy's disk and halo, high velocity clouds (HVCs), external galaxies, and the intergalactic medium.…

We present deep high-resolution (R~15,000) and high-quality UVES optical spectrophotometry of nine planetary nebulae with dual-dust chemistry. We compute physical conditions from several diagnostics. Ionic abundances for a large number of…

Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with…

We present integral field spectroscopy of two selected zones in the Orion Nebula obtained with the Potsdam Multi-Aperture Spectrophotometer (PMAS), covering the optical spectral range from 3500 to 7200 A and with a spatial resolution of 1".…

(Abridged) Main sequence massive stars embedded in an HII region should have the same chemical abundances as the surrounding nebular gas+dust. The Cocoon nebula, a close-by Galactic HII region ionized by a narrow line B0.5 V single star…

XMM-Newton observations of 19 galaxy clusters are used to measure the elemental abundances and their spatial distributions in the intracluster medium. The sample mainly consists of X-ray bright and relaxed clusters with a cD galaxy. Along…

We present the first attempt to determine the iron abundance in hot central stars of planetary nebulae. We perform an analysis with fully metal-line blanketed NLTE model atmospheres for a sample of ten stars (T_eff >= 70.000 K) for which…

We investigate relationships between observed auroral and nebular oxygen line fluxes in spectra of HII regions. We find a relation that is metallicity-dependent at low metallicities, but becomes independent of metallicity (within the…