Related papers: Oxygen and Nitrogen in Isolated Dwarf Irregular Ga…
We study how the void environment affects galactic chemical evolution by comparing the oxygen and nitrogen abundances of dwarf galaxies in voids with dwarf galaxies in denser regions. Using spectroscopic observations from SDSS DR7, we…
We present two samples of $\hii$ galaxies from the Sloan Digital Sky Survey (SDSS) spectroscopic observations data release 3. The electron temperatures($T_e$) of 225 galaxies are calculated with the photoionized $\hii$ model and $T_e$ of…
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 Nitrogen-to-Oxygen (N/O) abundance ratio is an important diagnostic of galaxy evolution since the ratio is closely tied to the growth of metallicity and the star formation history in galaxies. Estimates for the N/O ratio are…
We present the results of low dispersion optical spectroscopy of 186 H II regions spanning a range of radius in 13 spiral galaxies. Abundances for several elements (oxygen, nitrogen, neon, sulfur, and argon) were determined for 185 of the H…
(Abridged) We present deep WSRT observations of neutral hydrogen in 12 nearby elliptical and lenticular galaxies. The selected objects come from a representative sample of nearby galaxies earlier studied at optical wavelengths with the…
We present optical spectra of nine Galactic H II regions observed with the 10.4 m Gran Telescopio Canarias telescope and located at Galactocentric distances (RG) from 4 to 8 kpc. The distances of the objects have been revised using Gaia DR2…
We present results on carbon, nitrogen, and oxygen abundances for a sample of unevolved metal-poor stars with metallicities in the range -0.3< [Fe/H]< -3. Oxygen abundances derived from different indicators are compared showing consistently…
We suggest an empirical calibration for determination of oxygen and nitrogen abundances and electron temperature in HII regions where the [OII]3727+3729 line (R_2) is not available. The calibration is based on the strong emission lines of…
The metal content of a galaxy is a key property for distinguishing between viable galaxy evolutionary scenarios, and it strongly influences many of the physical processes in the interstellar medium. An absolute and robust determination of…
We present deep optical spectroscopy of eight HII regions located in the anticentre of the Milky Way. The spectra were obtained at the 10.4m GTC and 8.2m VLT. We determined Te([NII]) for all objects and Te([OIII]) for six of them. We also…
We present oxygen abundances relative to hydrogen (O/H) in the narrow line regions (NLRs) gas phases of Seyferts 1 (Sy 1s) and Seyferts 2 (Sy 2s) Active Galactic Nuclei (AGNs). We used fluxes of the optical narrow emission line intensities…
The observed oxygen abundances in a number of irregular galaxies have been compared with predictions of the closed-box model of chemical and photometric evolution of galaxies. Oxygen is found to be deficient with respect to the predicted…
We argue that isolated gas-rich dwarf galaxies -- in particular, dwarf irregular (dIrr) galaxies -- do not necessarily undergo significant gas loss. Our aim is to investigate whether the observed properties of isolated, gas-rich dwarf…
This Letter presents a new, remarkably simple diagnostic specifically designed to derive chemical abundances for high redshift galaxies. It uses only the H \alpha, [N II] and [S II] emission lines, which can usually be observed in a single…
The factors influencing chemical evolution of galaxies are poorly understood. Both gas inflow and gas outflow reduce a gas-phase abundance of heavy elements (metallicity) whereas the ongoing star formation continuously increases it. To…
The infrared (IR) range is extremely useful in the context of chemical abundance studies of the gas-phase interstellar medium (ISM) due to the large variety of ionic species traced in this regime, the negligible effects from dust…
We used the $H\alpha$ images from a large sample of nearby late-type dwarf galaxies to investigate properties of their emission structure. The sample consists of three hundred galaxies of the irregular (Irr), Magellanic irregular (Im), blue…
We have derived nebular abundances for 10 dwarf galaxies belonging to the M81 Group, including several galaxies which do not have abundances previously reported in the literature. For each galaxy, multiple H \ii regions were observed with…
We obtained new quantitative determinations of the nitrogen abundance and a consistent relation between nitrogen and oxygen abundances for a sample of Seyfert 2 galaxies located at redshift $z < 0.1$. We carried out this analysis using the…