Related papers: A Metallicity Map of M33
We present the results of an exhaustive study of the ionized gas in NGC 588, a giant H II region in the nearby spiral galaxy M33. This analysis uses a high number of diagnostics in the optical and infrared ranges. Four temperature…
We have obtained spectrophotometric observations of 41 anticenter planetary nebulae (PNe) located in the disk of the Milky Way. Electron temperatures and densities, as well as chemical abundances for He, N, O, Ne, S, Cl, and Ar were…
Spectroscopic observations of 63 HII regions in six spiral galaxies (NGC 628, NGC 783, NGC 2336, NGC 6217, NGC 7331, and NGC 7678) were carried out with the 6-meter telescope (BTA) of Russian Special Astrophysical Observatory with the…
We present the results of deep I and V-band photometry of the halo stars near the southeast minor axis of the Local Group spiral galaxy M33. An (I,V-I) color-magnitude diagram distinctly reveals the red giant branch stars at the bright end…
We present chemical abundances and radial velocities of six HII regions in the extremely metal-poor star-forming dwarf galaxy DDO 68. They are derived from deep spectra in the wavelength range 3500 - 10,000 {\AA}, acquired with the Multi…
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…
We present measurements of the [NII]/Ha ratio as a probe of gas-phase oxygen abundance for a sample of 419 star-forming galaxies at z=0.6-2.7 from the KMOS3D near-IR multi-IFU survey. The mass-metallicity relation (MZR) is determined…
We have derived element abundances in 310 emission-line galaxies from the Early Data Release of the Sloan Digital Sky Survey (SDSS) for which the [O {\sc iii}] 4363 emission line was detected, allowing abundance determination by direct…
Although measuring the gas metallicity in galaxies at various redshifts is crucial to constrain galaxy evolutionary scenarios, only rest-frame optical emission lines have been generally used to measure the metallicity. This has prevented us…
We present non-LTE analyses of four M33 early B-supergiant stars and five Galactic counterparts. This is the first time that B supergiants beyond the Magellanic Clouds are analyzed by means of detailed Non-LTE techniques. Stellar…
We present deep, narrowband imaging of the nearby spiral galaxy M101 and its satellites to analyze the oxygen abundances of their HII regions. Using CWRU's Burrell Schmidt telescope, we add to the narrowband dataset of the M101 Group,…
In the framework of the study of the evolutionary status of galaxies in the nearby Lynx-Cancer void, we present the results of the SAO RAS 6-m telescope spectroscopy for 20 objects in this region. The principal faint line [OIII]4363A, used…
The metallicity structure of the Milky Way disk stems from the chemodynamical evolutionary history of the Galaxy. We use the National Radio Astronomy Observatory Karl G. Jansky Very Large Array to observe ~8-10 GHz hydrogen radio…
Accurately determining the elemental abundances of a low metallicity nebula strongly depends on measuring the density (n$_e$) and temperature (T$_e$) of the gas. Because these two parameters are inherently degenerate when derived solely…
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…
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…
We use a sample of 37 H II regions with high quality spectra to study the behavior of the relative abundances of several elements as a function of metallicity. The sample includes spectra for eight H II regions of the Magellanic Clouds,…
Simple relations for deriving the oxygen abundance in HII regions with intensities of the three strong emission lines R_2, R_3, and N_2 (R calibration) or S_2, R_3, and N_2 (S calibration) in their spectra are suggested. A sample of 313…
We present metallicity gradients in 49 local field star-forming galaxies. We derive gas-phase oxygen abundances using two widely adopted metallicity calibrations based on the [OIII]/Hbeta, [NII]/Halpha and [NII]/[OII] line ratios. The two…
The study of group properties of the extremely metal-deficient gas-rich local dwarfs is very promising for the understanding the galaxy formation process at high redshifts. About 20 such objects have been picked up from the literature in…