Related papers: The oxygen abundance distribution in M101
Oxygen abundances in the spiral galaxies expected to be richest in oxygen are estimated. The new abundance determinations are based on the recently discovered ff-relation between auroral and nebular oxygen line fluxes in HII regions. We…
We present non-LTE oxygen abundances for a sample of B stars in the Orion association. The abundance calculations included non-LTE line formation and used fully blanketed non-LTE model atmospheres. The stellar parameters were the same as…
This paper presents a spectroscopic investigation of 11 HII regions in the nearby galaxy NGC 2403. The HII regions are observed with a long-slit spectrograph mounted on the 2.16 m telescope at XingLong station of National Astronomical…
We analyze the reliability of oxygen abundances and ionization parameters obtained from different diagnostic diagrams. For this, we compiled from the literature observational emission line intensities and oxygen abundance of 446…
We present spectroscopic observations of a sample of 72 emission-line objects, including mainly HII regions, in the spiral galaxy M 33. Spectra were obtained with the multi-object, wide field spectrograph AF2/WYFFOS at the 4.2m WHT…
The dispersion in chemical abundances provides a very strong constraint on the processes that drive the chemical enrichment of galaxies. Due to its proximity, the spiral galaxy M33 has been the focus of numerous chemical abundance surveys…
To revisit the long-standing problem of possible inconsistency concerning the oxygen composition in the current galactic gas and in the solar atmosphere (i.e., the former being appreciably lower by ~0.3 dex) apparently contradicting the…
(Abridged) We use high S/N spectra of 20 HII regions in the giant spiral galaxy M101 to derive electron temperatures for the HII regions and robust metal abundances over radii R = 0.19-1.25 Ro (6-41 kpc). We compare the consistency of…
The oxygen and nitrogen abundances in the HII regions of the nine Virgo spirals of the sample from Skillman et al (1996) and in nine field spiral galaxies are re-determined with the recently suggested P - method. We confirm that there is an…
We determine the radial abundance gradient of helium in the disc of the Galaxy from published spectra of 19 $\text{H}\thinspace \text{II}$ regions and ring nebulae surrounding massive O stars. We revise the Galactocentric distances of the…
We present chemical abundances of carbon and oxygen in the Large and Small Magellanic Clouds from optical spectra of H II regions. We analyse the behaviour of the O/H, C/H and C/O abundances ratios and their spatial distribution inside the…
The oxygen abundance gradients among nebular emission line regions in spiral galaxies have been used as important constraints for models of chemical evolution. We present the largest ever full-wavelength optical spectroscopic sample of…
We considered two sequences of spiral galaxies with different shapes of the radial gas-phase oxygen abundance distributions from the galaxies in the MaNGA survey: (1) Galaxies in which the gradient is well approximated by a single linear…
By using the Hectospec 6.5 m Multiple Mirror Telescope (MMT) and the 2.16 m telescope of National Astronomical Observatories, Chinese Academy of Sciences (NAOC), we obtained 188 high signal-to-noise ratio (S/N) spectra of HII regions in the…
The debate on the oxygen abundances of metal-poor stars has its origin in contradictory results obtained using different abundance indicators. To achieve a better understanding of the problem we have acquired high quality spectra with the…
We considered five galaxies in the MaNGA survey that show distinct azimuthal asymmetry in the abundance, in the sense that in the inner part (more than half of the optical radius, $R_{25}$) of each galaxy there is a sector-like region where…
We derive the oxygen abundance (O/H), the nitrogen-to-oxygen (N/O) abundance ratio, and their corresponding radial gradients for a sample of 1431 galaxies from MaNGA DR15 survey using two different realizations of the strong line method:…
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…
A detailed spectroscopic study, from lambda 3700 A to 1 um, was performed for a sample of 34 HII galaxies in order to derive fundamental parameters for their HII regions and ionizing sources, as well as gaseous metal abundances. All the…
We present deep spectrophotometry of several Hii regions in the nearby low-mass spiral galaxies NGC 300 and M33. The data have been taken with UVES and OSIRIS spectrographs attached to the 8m VLT and 10.4m GTC telescopes, respectively. We…