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"Lombardo, Linda"
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Evaluation and stance in war news : a linguistic analysis of American, British and Italian television news reporting of the 2003 Iraqi war
\"Evaluation and Stance in War News functions as a tool kit for the critical evaluation of language in the news, both as raw data in need of interpretation and as carefully packaged products of 'information management' in need of 'unpacking'. The chapters offer an array of theoretical and empirical instruments for revealing, identifying, sifting, weighing and connecting patterns of language use that construct messages. These messages carry with them world views and value systems that can either create an ever wider divide or serve to build bridges between peoples and countries.\"--Jacket.
Book
Constraining nucleosythesis in neutrino-driven winds using the impact of ( α , xn) reaction rates
The lighter heavy elements of the first r-process peak, between strontium and silver, can be synthesized in the moderately neutron-rich neutrino–driven ejecta of either core–collapse supernovae or neutron star mergers via the weak r–process. This nucleosynthesis scenario exhibits uncertainties from the absence of experimental data from ( α , xn ) reactions on neutron–rich nuclei, which are currently based on statistical model estimates. We have performed a new impact study to identify the most important ( α , xn ) reactions that can affect the production of the lighter heavy elements under different astrophysical conditions using new, constrained ( α , xn ) reaction rates based on the Atomki-V2 α OMP. Our results show how when reducing the nuclear physics uncertainties, we can use abundance ratios to constrain the astrophysical conditions/environment. This can be achieved in the near future, when the key ( α , xn ) reaction rates will be measured experimentally in radioactive beam facilities.
Journal Article
Osmium Abundances in Galactic Halo Stars at Intermediate Metallicities
Osmium is a third-peak neutron-capture element predominantly produced by the rapid (r-) process, and it is a valuable tracer of early Galactic chemical enrichment. However, osmium abundance measurements in Galactic stars remain limited due to observational challenges. We present new osmium abundances for 23 stars at intermediate metallicities (−2.5≤ [Fe/H] ≤−1.0) within the framework of the MINCE (Measuring at Intermediate Metallicity Neutron-Capture Elements) project. A standard abundance analysis was carried out using one-dimensional LTE model atmospheres and the optical Os I line at 479 nm observed in high-quality UVES spectra. The derived [Os/Fe] ratio exhibits an anticorrelation with [Fe/H], supporting efficient r-process enrichment during the early phases of the Milky Way’s evolution. We also investigated Os abundances across different Galactic components, finding that halo and Gaia–Sausage–Enceladus stars are more Os-rich than thick-disk stars. A comparison between Os and europium abundances supports a common r-process origin for these elements at intermediate metallicities.
Journal Article
Molybdenum Abundances in MINCE Stars
Molybdenum (Mo, Z = 42) is a neutron-capture element with seven stable isotopes that can be produced by different processes. Previous studies have shown a large scatter in molybdenum abundances for metal-poor ([Fe/H] < −1) stars, indicating that multiple nucleosynthetic channels are responsible for molybdenum production even at very low metallicity. To understand which different nucleosynthesis processes are involved in the chemical enrichment of this element in the Galaxy, a large sample of precise molybdenum abundance is required. In this study, we present molybdenum abundances of 27 metal-poor stars from the Measuring at Intermediate Metallicity Neutron-Capture Elements project sample. We derived molybdenum abundances using three Mo i lines at 550.6 nm, 557.0 nm, and 603.0 nm, which proved to be reliable for measuring Mo abundances in giant stars with [Fe/H] >−2. Our derived [Mo/Fe] abundance ratios show on average slightly higher values (∼0.2 dex) compared to the literature samples. This may be due to an observational bias or to non-local thermodynamic equilibrium effects. We also found that Gaia-Sausage-Enceladus candidate stars have lower [Mo/Fe] than the sample average, while the only Sequoia candidate star has a higher [Mo/Fe] than most sample stars.
Journal Article
Evaluation and stance in war news : a linguistic analysis of American, British and Italian television news reporting of the 2003 Iraqi war
In a world in which advanced communication technologies have made the reporting of disasters and conflicts (also in the form of breaking news) a familiar and 'normalised' activity, the information we present here about television news reporting of the 2003 war in Iraq has implications that go beyond this particular conflict.
eBook
Using (α, xn) reaction rates and abundance ratios to constrain the weak r-process
The lighter heavy elements of the first r-process peak, between strontium and silver, can be synthesized in the moderately neutron-rich neutrino–driven ejecta of either core–collapse supernovae or neutron star mergers via the weak r–process. This nucleosynthesis scenario exhibits uncertainties from the absence of experimental data from ( α, xn ) reactions on neutron–rich nuclei, which are currently based on statistical model estimates. We have performed a new impact study to identify the most important ( α, xn ) reactions that can affect the production of the lighter heavy elements under different astrophysical conditions and using new, constrained ( α, xn ) reaction rates based on the Atomki-V2 α OMP. We have identified a list of relevant reactions that affect elemental abundance ratios that can be compared to abundances from metal-poor stars. Our results show how when reducing the nuclear physics uncertainties, we can use abundance ratios to constrain the astrophysical conditions/environment. This will be possible with the planned experiments to measure key ( α, xn ) reaction rates using the SECAR recoil separator at FRIB that will also be briefly discussed.
Journal Article
Young giants of intermediate mass Evidence of rotation and mixing
In the search of a sample of metal-poor bright giants using Str{\"o}mgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, some of which have high rotational velocities.We determined the chemical composition and rotational velocities of these stars in order to compare them with predictions from stellar evolution models. These stars where of spectral type A to B when on the main sequence, and we therefore wished to compare their abundance pattern to that of main-sequence A and B stars.Stellar masses were derived by comparison of the position of the stars in the colour-magnitude diagram with theoretical evolutionary tracks. These masses, together with Gaia photometry and parallaxes, were used to derive the stellar parameters. We used spectrum synthesis and model atmospheres to determine chemical abundances for 16 elements (C, N, O, Mg, Al, Ca, Fe, Sr, Y, Ba, La, Ce, Pr, Nd, Sm, and Eu) and rotational velocities.The age-metallicity degeneracy can affect photometric metallicity calibrations. We identify 15 stars as likely binary stars. All stars are in prograde motion around the Galactic centre and belong to the thin-disc population. All but one of the sample stars present low [C/Fe] and high [N/Fe] ratios together with constant [(C+N+O)/Fe], suggesting that they have undergone CNO processing and first dredge-up. The observed rotational velocities are in line with theoretical predictions of the evolution of rotating stars.
Paper
Purveyors of fine halos III. Chemical abundance analysis of a potential omega Cen associate
Globular clusters (GCs) are important donors to the build-up of the Milky Way (MW) stellar halo, having contributed at the ten percent level over the Galactic history. Stars that originated from the second generation of dissolved or dissolving clusters can be readily identified via distinct light-element signatures such as enhanced N and Na and simultaneously depleted C and O abundances. In this paper we present an extensive chemical abundance analysis of the halo star J110842, which was previously kinematically associated with the massive MW GC \\(\\omega\\) Centauri (\\(\\omega\\)Cen), and we discuss viable scenarios from escape to encounter. Based on a high-resolution, high signal-to-noise spectrum of this star using the UVES spectrograph, we were able to measure 33 species of 31 elements across all nucleosynthetic channels. The star's low metallicity of [FeII/H]=$-2.10$$\\pm\\(0.02(stat.)\\)\\pm0.07\\((sys.) dex places it in the lower sixth percentile of \\)\\omega\\(Cen's metallicity distribution. We find that all of the heavier-element abundances, from \\)\\alpha\\(- and Fe-peak elements to neutron-capture elements are closely compatible with \\)\\omega\\(Cen's broad abundance distribution. However, given the major overlap of this object's abundances with the bulk of all of the MW components, this does not allow for a clear-cut distinction of the star's origin. In contrast, our measurements of an enhancement in CN and its position on the Na-strong locus of the Na-O anticorrelation render it conceivable that it originally formed as a second-generation GC star, lending support to a former association of this halo star with the massive GC \\)\\omega$Cen.
Paper
Chemical Evolution of R-process Elements in Stars (CERES) II. The impact of stellar evolution and rotation on light and heavy elements
Context. Carbon, nitrogen, and oxygen are the most abundant elements throughout the universe, after hydrogen and helium. Studying these elements in low-metallicity stars can provide crucial information on the chemical composition in the early Galaxy and possible internal mixing processes that can alter the surface composition of the stars. Aims. This work aims to investigate the chemical abundance patterns for CNO elements and Li in a homogeneously analyzed sample of 52 metal-poor halo giant stars. Methods. We used high-resolution spectra with a high signal-to-noise ratio (S/N) to carry out a spectral synthesis to derive detailed C, N, O, and Li abundances for a sample of stars with metallicities in the range of -3.58 <= [Fe/H] <= -1.79 dex. Our study was based on the assumption of one-dimensional (1D) local thermodynamic equilibrium (LTE) atmospheres. Results. Based on carbon and nitrogen abundances, we investigated the deep mixing taking place within stars along the red giant branch (RGB). The individual abundances of carbon decrease towards the upper RGB while nitrogen shows an increasing trend, indicating that carbon has been converted into nitrogen. No signatures of ON-cycle processed material were found for the stars in our sample. We computed a set of galactic chemical evolution (GCE) models, implementing different sets of massive star yields, both with and without including the effects of stellar rotation on nucleosynthesis. We confirm that stellar rotation is necessary to explain the highest [N/Fe] and [N/O] ratios observed in unmixed halo stars. The predicted level of N enhancement varies sensibly in dependence of the specific set of yields that are adopted. For stars with stellar parameters similar to those of our sample, heavy elements such as Sr, Y, and Zr appear to have unchanged abundances despite the stellar evolution mixing processes.
Paper