Related papers: Abundances of Disk Planetary Nebulae in M31 and th…
Radial abundance gradients provide sound constraints for chemo-dynamical models of galaxies. Azimuthal variations of abundance ratios are solid diagnostics to understand their chemical enrichment. In this paper we investigate azimuthal…
We review chemical evolution models developed for M31 as well as the abundance determinations available for this galaxy. Then we present a recent chemical evolution model for M31 including radial gas flows and galactic fountains along the…
Absolute and differential chemical abundances are presented for the largest group of massive stars in M31 studied to date. These results were derived from intermediate resolution spectra of seven B-type supergiants, lying within four OB…
Radio continuum observations trace thermal emission of ionized plasma in planetary nebulae and bring useful information on nebular geometries. A model of homogeneous sphere or shell cannot fit the nebular spectra and brightness…
We present high S/N spectroscopy of 15 emission-line galaxies (ELGs) cataloged in the KPNO International Spectroscopic Survey (KISS), selected for their possession of high equivalent width [O III] lines. The primary goal of this study was…
We have carried out mid-infrared spectroscopy of seven Galactic proto-planetary nebulae (PPNs) using the Spitzer Space Telescope. They were observed from 10-36 microns at relatively high spectral resolution, R~600. The sample was chosen…
(Abridged) Planetary nebulae (PNe) around Wolf-Rayet [WR] central stars ([WR]PNe) constitute a particular photoionized nebula class that represents about 10% of the PNe with classified central stars. We analyse deep high-resolution…
From a spectroscopic survey of candidate H II regions in the Andromeda galaxy (M31) with MMT/Hectospec, we have identified 294 H II regions using emission line ratios and calculated elemental abundances from strong-line diagnostics (values…
Non-LTE abundances of magnesium, aluminum and sulfur are derived for a sample of 23 low-v \sin i stars belonging to six northern OB associations of the Galactic disk within 1 kpc of the Sun. The abundances are obtained from the fitting of…
(Abridged) We have obtained spectra of 135 HII regions located in the inner and extended disks of the spiral galaxies NGC 1512 and NGC 3621, spanning the range of galactocentric distances 0.2-2 x R25 (from 2-3 kpc to 18-25 kpc). We find…
The planetary nebula TS 01 (also called PN G 135.9+55.9 or SBS 1150+599A), with its record-holding low oxygen abundance and its double degenerate close binary core (period 3.9 h), is an exceptional object located in the Galactic halo. We…
We present the results of a large-scale survey of neutron(n)-capture elements in Galactic planetary nebulae (PNe), undertaken to study enrichments from s-process nucleosynthesis in their progenitor stars. From new K band observations of…
We present the result of photo-ionizing modelling of the three planetary nebulae (PNe) A 20, A 15 and MeWe 1-3. All three objects are roughly roundish, highly excited and have a high galactic $z$. The PNe displayed low densities in the…
We present new spectroscopic observations of 13 H II regions in the Local Group spiral galaxy M33. The regions observed range from 1 to 7 kpc in distance from the nucleus. Of the 13 H II regions observed, the [O III] 4363 Angstrom line was…
The spectra of the planetary nebulae NGC3242 and NGC6369 are reanalysed using spectral measurements made in the mid-infrared with the Spitzer Space Telescope and the Infrared Space Observatory (ISO). The aim is to determine the chemical…
We present an overview of the distributions of 11 elemental abundances in the Milky Way's inner regions, as traced by APOGEE stars released as part of SDSS Data Release 14/15 (DR14/DR15), including O, Mg, Si, Ca, Cr, Mn, Co, Ni, Na, Al, and…
Open clusters are distributed all across the disk and are convenient tracers of its properties. In particular, outer disk clusters bear a key role for the investigation of the chemical evolution of the Galactic disk. The goal of this study…
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…
Much of our understanding of dark matter halos comes from the assumption that the mass-to-light ratio (M/L) of spiral disks is constant. The best way to test this hypothesis is to measure the disk surface mass density directly via the…
We present the preliminary analysis of a deep (100ks) XMM-Newton observation of M82. The spatial distribution of the abundances of chemical elements (Fe, O, Ne, Mg, Si, S) is investigated through narrow-band imaging analisys and…