Related papers: The impact of atomic data selection on nebular abu…
At variance from 2H, 3He and 4He abundances, 7Li abundance data yield an extra constraint to cosmological parameters, in top of those deriving from CMB, BAO, SNIa or H0 data. This constraint, often disregarded, would favor smaller $\Omega_b…
The iron depletion factors found in Galactic planetary nebulae (PNe) span over two orders of magnitude, suggesting that there are differences in the grain formation and destruction processes from object to object. We explore here the…
Charge-exchange reactions are versatile probes for nuclear structure. In particular, when populating isobaric analog states, these reactions are used to study isovector nuclear densities and neutron skins. The quality of the information…
We present a spectrum of the planetary nebula M 2-36 obtained using the Ultra Violet and Visual Echelle Spectrograph (UVES) at the Very Large Telescope (VLT). 446 emission lines are detected. We perform an analysis of the chemical…
Tests of big bang nucleosynthesis and early universe cosmology require precision measurements for helium abundance determinations. However, efforts to determine the primordial helium abundance via observations of metal poor H II regions…
The origin of the abundance discrepancy is one of the key problems in the physics of photoionized nebula. In this work, we analize and discuss data for a sample of Galactic and extragalactic HII regions where this abundance discrepancy has…
We conducted research on the classification and physical properties of 10 objects from the HASH (Hong Kong/Australian Astronomical Observatory/Strasbourg Observatory H-alpha Planetary Nebula (PN)) database with small angular sizes (<…
We present spectrophotometry of 12 Galactic and 3 Magellanic Cloud planetary nebulae (PNe). Nine of the Galactic PNe were observed by scanning the slit across the PN. We use the fluxes of collisionally excited lines (CELs) to derive…
Molecular oxygen has been the subject of many observational searches as chemical models predicted it to be a reservoir of oxygen. Although it has been detected in two regions of the interstellar medium, its rarity is a challenge for…
We carry out direct numerical simulations of turbulent astrophysical media exposed to the redshift zero metagalactic background. The simulations assume solar composition and explicitly track ionizations, recombinations, and ion-by-ion…
Many extensions of the Standard Model predict large numbers of additional unstable particles whose decays in the early universe are tightly constrained by observational data. For example, the decays of such particles can alter the ratios of…
Supersonic turbulence results in strong density fluctuations in the interstellar medium (ISM), which have a profound effect on the chemical structure. Particularly useful probes of the diffuse ISM are the ArH$^+$, OH$^+$, H$_2$O$^+$…
The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14~elements produced in various nuclear-synthesis processes for 90~open…
It is argued that an important fraction of PNe present large temperature variations that are not due to observational errors nor to incomplete atomic physics. Seven possible causes for these variations are reviewed, one of them is presented…
Opacities and chemical abundance data are crucial ingredients of ultracool dwarf and extrasolar giant planet atmosphere models. We report here on the detailed sources of molecular opacity data employed by our group for this application. We…
Chemical tagging is a central pursuit of galactic archaeology, but requires sufficiently discriminative abundances to uniquely identify sites of star formation. This task is complicated by intrinsic scatter among conatal stars,…
In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances…
We have computed a grid of hydrostatic spherical COMARCS models for C stars covering metallicities from [Z/H]=0 to -2 and values of the carbon excess [C-O] from 6.41 to 9.15, plus some temperature sequences, where the amount of oxygen and…
We have evolved a series of thirteen complete solar models that utilize different assumed heavy element compositions. Models that are based upon the heavy element abundances recently determined by Asplund, Grevesse, and Sauval (2005) are…
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…