Related papers: Chemistry in the dIrr galaxy Leo A
We present elemental abundances for multiple HII regions in Leo A and GR 8 obtained from long slit optical spectroscopy of these two nearby low luminosity dwarf irregular galaxies. As expected from their luminosities, and in agreement with…
Study the ionized gas in metal-poor environments is key to understanding the mechanisms regulating galaxy evolution. However, most of the previous studies of extragalactic HII regions rely on unresolved observations of gaseous structures.…
We use previously-published moderate-resolution spectra in combination with stellar atmosphere models to derive the first measured chemical abundance ratios in the Leo II dSph galaxy. We find that for spectra with SNR > 24, we are able to…
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 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 have obtained spectra of 102 red giant branch (RGB) stars in the Leo I dwarf spheroidal galaxy (dSph) and 74 RGB stars in the Leo II dSph using LRIS on the Keck I 10-meter Telescope. We report on the calcium abundances [Ca/H] derived…
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…
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…
We have obtained multi-object spectroscopy of H II regions in the spiral galaxy M51 with the Keck I telescope and the Low Resolution Imaging Spectrometer. For 10 objects we have detected the auroral line [N II] 5755, while [S III] 6312 has…
Ions (e.g., H$_3^+$, H$_2$O$^+$) have been used extensively to quantify the cosmic-ray ionization rate (CRIR) in diffuse sightlines. However, measurements of CRIR in low-to-intermediate density gas environments are rare, especially when…
For the first time, the argon abundance relative to hydrogen abundance (Ar/H) in the narrow line region of a sample of Seyfert 2 nuclei has been derived. In view of this, optical narrow emission line intensities of a sample of 64 local…
(abridged) We present deep spectroscopy of a large sample of low-metallicity emission-line galaxies. The main goal of this study is to derive element abundances in these low-metallicity galaxies. We analyze 121 VLT spectra of HII regions in…
(Shortened version) We report optical spectroscopy of 16 H II regions in NGC 1705 and [O III] 4363 detections for the first time in five H II regions. The resulting mean oxygen abundance derived directly from measured electron temperatures…
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…
We show that in order to minimize the uncertainties in the N and O abundances of low mass, low metallicity (O/H less than or equal to solar/5) emission-line galaxies, it is necessary to employ separate parameterizations for inferring Te[N…
We conducted a long-slit spectrophotometry analysis to obtain the chemical abundances of seven metal-poor HII regions in three galaxies: UM 160, UM 420, and TOL 0513-393. The data have been taken with the Focal Reducer Low Dispersion…
(Abridged) We have obtained new spectrophotometric data for 28 HII regions in the spiral galaxy NGC 300, a member of the nearby Sculptor Group. The detection of auroral lines, including [OIII]4363, [SIII]6312 and [NII]5755, has allowed us…
In this work, we investigated the nitrogen and oxygen abundances in a sample of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their nucleus. Optical spectroscopic data (3 600 - 10 000 {\AA}) of 40 LINERs from the Mapping…
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…
The determination of the heavy element abundances from giant extragalactic H II regions is based on collisionally excited lines. We argue that in the presence of temperature variations the abundances determined are lower limits to the real…