Related papers: The oxygen abundance gradient in M101: the reliabi…
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…
We study the sensitivity of the methods available for abundance determinations in H II regions to potential observational problems. We compare the dispersions they introduce around the oxygen and nitrogen abundance gradients when applied to…
(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 compilation of published spectra of Galactic HII regions with available diagnostic [OIII]4363 line has been carried out. Our list contains 71 individual measurements of 13 HII regions in the range of galactocentric distances from 6.6 to…
The well-observed spiral galaxy M101 was considered. The radial distributions of oxygen abundances determined in three different ways (with the classic Te - method, with the R23 - method, and with the P -- method) were compared. It was…
We have obtained multi-slit spectroscopic observations from 3700A to 9200A with LRIS at the Keck I telescope for 31 HII regions in the disk of the Andromeda galaxy (M31), spanning a range in galactocentric distance from 3.9 kpc to 16.1 kpc.…
This is our second paper devoted to the problem of line intensity - oxygen abundance calibration starting from the idea of McGaugh (1991) that the strong oxygen lines contain the necessary information to determine accurate abundances in HII…
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…
We present deep spectrophotometry of 18 HII regions in the nearby massive spiral galaxies M101 and M31. We have obtained direct determinations of electron temperature in all the nebulae. We detect the CII 4267 line in several HII regions,…
The extended HI disk and tidal tails of M81 present an interesting environment to study the effects of galaxy interaction on star formation and chemical evolution of the outer disk of a large spiral galaxy. We present H{\alpha} imaging 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…
While collisionally excited lines in HII regions allow one to easily probe the chemical composition of the interstellar medium in galaxies, the possible presence of important temperature fluctuations casts some doubt on the derived…
We present initial results from the M33 Metallicity Project. Out of the thousands of cataloged HII regions in M33, only ~30 have electron-temperature based abundances in the literature. We have obtained Keck spectroscopy of a sample of ~200…
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,…
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…
Using a sample of 28 HII regions from the literature with measured temperature inhomogeneity parameter, t^2, we present a statistical correction to the chemical abundances determined with the Te(4363/5007) method. We used the t^2 values to…
The discrepancy between the oxygen abundances in high-metallicity HII regions determined through the Te-method (and/or through the corresponding "strong lines - oxygen abundance" calibration) and that determined through the model fitting…
New optical spectra of 28 H II regions in the M101 disk have been obtained, yielding 10 new detections of the [O III]{\lambda}4363 auroral line. The oxygen abundance gradient measured from these data, combined with previous observations,…
We present high signal-to-noise spectrophotometric observations of seven luminous HII galaxies. The observations have been made with the use of a double-arm spectrograph which provides spectra with a wide wavelength coverage, from 3400 to…
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…