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We exploit the unprecedented depth of integral field data from the KMOS Ultra-deep Rotational Velocity Survey (KURVS) to analyse the strong (H alpha) and forbidden ([MI], [SII]) emission line ratios in 22 main-sequence galaxies at z approximate to 1.5. Using the (NII]/H alpha emission-line ratio, we confirm the presence of the stellar mass-gas-phase metallicity relation at this epoch, with galaxies exhibiting on average 0.13 +/- 0.04 dex lower gas-phase metallicity (12 + log(O/H)(M13) = 8.40 +/- 0.03) for a given stellar mass (log(10)(M-*[M-circle dot] = 10.1 +/- 0.1) .than local main-sequence galaxies. We determine the galaxy-integrated [SII] doublet ratio, with a median value of [SII]lambda 6716/lambda 6731 = 1.26 +/- 0.14 equivalent to an electron density of log(10)(n(e)[cm(-3)]) = 1.95 +/- 0.12. Utilising CANDELS HST multi-band imaging we define the pixel surface-mass and star-formation rate density in each galaxy and spatially resolve the fundamental metallicity relation at z approximate to 1.5, finding an evolution of 0.05 +/- 0.01 dex compared to the local relation. We quantify the intrinsic gas-phase metallicity gradient within the galaxies using the [NII]/H alpha calibration, finding a median annuli-based gradient of Delta Z/Delta R = -0.015 +/- 0.005 dex kpc(-1). Finally, we examine the azimuthal variations in gas-phase metallicity, which show a negative correlation with the galaxy integrated star-formation rate surface density (r(s) = -0.40, p(s) = 0.07) but no connection to the galaxies kinematic or morphological properties nor radial variations in stellar mass surface density or star formation rate surface density. This suggests both the radial and azimuthal variations in interstellar medium properties are connected to the galaxy integrated density of recent star formation.

The determination of the solar oxygen abundance is a topic that has long beenunder debate, where the exact value has varied between researchers. These variationsin the oxygen abundance have implications on our understanding of the Sun and itsinterior as well as our understanding of other stars. The aim of this report is to explorethe di erences between three observations; the Liège, Hamburg and SST, and their effecton the solar oxygen abundance calculated from the 777 nm triplet. In the reportit was found that the abundance from the Liège and SST data was lower and in betteragreement (A(O) ≈ 8.709 dex) compared to the Hamburg data (A(O) ≈ 8.732 dex).One of the potential reasons for these di erences explored in the thesis were the e ectsof magnetic elds. After comparing the di erences it was argued that the SST dataset as well as the Liège could be considered more reliable compared to the Hamburg.The argued abundance was therefore of a somewhat lower value which does not helplessen the inconsistency between solar models and helioseismology. Bestämningen av mängden syre i solen har länge varit ett debatterat område där det exakta numeriska värdet varierat bland forskare. Dessa variationer av mängden syre ger konsekvenser för vår förståelse av solen och dess inre samt för vår förståelse av andra stjärnor. Syftet med denna rapport är att utforska skillnaderna mellan tre observationer; från Liège, Hamburg och SST, samt deras påverkan på mängden syre i solen beräknad från 777 nm tripletten. Rapporten fann att mängden syre beräknad från Liège- och SST-datan både var lägre samt stämde bättre överens (A(O) ≈ 8.709 dex) i jämförelse med mängden från Hamburg observationen (A(O) ≈ 8.732 dex). En potentiell anledning till skillnaden i resultat som utforskades i denna uppsats var påverkan av magnetiska fält. Efter jämförelse av skillnaderna kunde det konstateras att datan från SST så väl som från Liège kan anses mer pålitliga i förhållande till Hamburg-datan. Den förespråkade mängden syre var åt det lägre hållet vilket inte bidrar till minskningen av avvikelserna mellan modeller av solen och mätningar via helioseismologi.

Understanding the spatial distribution of metals within galaxies allows us to study the processes of chemical enrichment and mixing in the interstellar medium. In this work, we map the 2D distribution of metals using a Gaussian Process Regression (GPR) for 19 star-forming galaxies observed with the Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT–MUSE) as a part of the PHANGS–MUSE survey. We find that 12 of our 19 galaxies show significant 2D metallicity variation. Those without significant variations typically have fewer metallicity measurements, indicating this is due to the dearth of ${\rm H\, {\small II}}$ regions in these galaxies, rather than a lack of higher-order variation. After subtracting a linear radial gradient, we see no enrichment in the spiral arms versus the disc. We measure the 50 per cent correlation scale from the two-point correlation function of these radially subtracted maps, finding it to typically be an order of magnitude smaller than the fitted GPR kernel scale length. We study the dependence of the two-point correlation scale length with a number of global galaxy properties. We find no relationship between the 50 per cent correlation scale and the overall gas turbulence, in tension with existing theoretical models. We also find more actively star-forming galaxies, and earlier type galaxies have a larger 50 per cent correlation scale. The size and stellar mass surface density do not appear to correlate with the 50 per cent correlation scale, indicating that perhaps the evolutionary state of the galaxy and its current star formation activity is the strongest indicator of the homogeneity of the metal distribution.

We present a spatially resolved study of the relation between dust and metallicity in the nearby spiral galaxies M 101 (NGC 5457) and NGC 628 (M 74). We explore the relation between the chemical abundances of their gas and stars with their dust content and their chemical evolution. The empirical spatially resolved oxygen effective yield and the gas-to-dust mass ratio (GDR) across both disc galaxies are derived, sampling 1 dex in oxygen abundance. We find that the metal budget of the NGC 628 disc and most of the M 101 disc appears consistent with the predictions of the simple model of chemical evolution for an oxygen yield between half and one solar, whereas the outermost region (R ≥ 0.8 R 25 ) of M 101 presents deviations suggesting the presence of gas flows. The GDR-metallicity relation shows a two slopes behaviour, with a break at 12 + log(O/H) ≈ 8.4, a critical metallicity predicted by theoretical dust models when stardust production equals grain growth. A relation between GDR and the fraction of molecular to total gas, ΣH 2 }/Σ gas is also found. We suggest an empirical relationship between GDR and the combination of 12 + log(O/H), for metallicity, and ΣH 2 /Σ gas , a proxy for the molecular clouds fraction. The GDR is closely related with metallicity at low abundance and with ΣH 2 /Σ gas for higher metallicities suggesting interstellar medium dust growth. The ratio Σ dust /Σ star correlates well with 12+ log(O/H) and strongly with log(N/O) in both galaxies. For abundances below the critical one, the 'stardust' production gives us a constant value suggesting a stellar dust yield similar to the oxygen yield. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society., This work was partially supported by the Spanish Ministerio de Economia y Competitividad under grants AYA2016-79724-C4-4-P and AYA2016-79724-C4-3-P, and excellence project PEX2011-FQM-7058 of Junta de Andalucia (Spain). MR acknowledges support by the research projects AYA2014-53506-P and AYA2017-84897-P from the Spanish Ministerio de Economia y Competitividad and Junta de Andalucia grant FQM108; support from the European Regional Development Funds (FEDER) is acknowledged.

We present new accurate measurements of the mass, metallicity and star-formation rate of a statistically significant sample of 93 galaxies at z greater than or similar to 2 using near-infrared spectroscopy taken as part of the 3D-Hubble Space Telescope survey. We derive a mass-metallicity relation (MZR) for our sample with metallicities based on the oxygen and Hβ nebular emission lines. We find the MZR derived from our data to have the same trend as previous determinations in the range 0

The abundances of the planetary nebulae (PNe) in the galactic bulge are presented. Comparisons are made with the disk nebulae, the solar values, and the prediction based on the observed gradients in the disk. The mean abundances in the bulge PNe cannot be predicted by the observed gradient in the disk sample. Except for helium and nitrogen, which are systematically higher in the bulge, all other elements show distributions similar to their counterparts in the disk PNe. The relatively older age of the bulge objects suggests a much faster enhancement in the bulge. The significantly higher mean N/O ratio in the bulge PNe compared to the disk PNe, is caused by the much larger fraction of low abundance nebulae with a high N/O ratio in the bulge, rather than by having -on average- more massive progenitors. This is argued since the low abundance is noticed not only in the case of oxygen, which could be largely reduced if we allow for a more intensive ON-cycle to occur, but also in the cases of neon, sulfur, and argon - the elements which are believed to be essentially untouched by the nucleosynthesis in the PN progenitors.Several lines of evidence strongly argue that in the bulge, the production rates of elements and isotopes mostly produced in low and intemediate stars relative to those of elements mainly produced in massive stars, are higher than the corresponding ratios in the solar neighbourhood or in other positions in the disk. This probably indicates an initial mass function in the bulge which is different from that in the rest of the Galaxy.An evolutionary scenario for the bulge, allowing for a more efficient star formation and a much shorter timescale to collapse than in the disk, with an initial mass function such that the fraction of massive stars is lower than in the solar neighbourhood, is then proposed to explain the exisiting data.

Abundance determinations of about 110 planetary nebulae, which are likely to be in the Galactic Bulge are presented. Plasma diagnostics have been performed by making use of the available forbidden line ratios combined with radio continuum measurements. Chemical abundances of He, O, N, Ne, S, Ar, and Cl are then derived by employing theoretical nebular models as interpolation devices in establishing the ionization correction factors (ICFs) used to estimate the distribution of atoms among unobserved ionization stages. The overall agreement between the results derived by using the model-ICFs and those obtained from the theoretical models is reasonably good. The uncertainties related to the total abundances show a clear dependence on the level of excitation. In most cases, the abundances of chlorine can be derived only in objects with a relatively high Cl-abundance. Contrary to the conclusion previously drawn by Webster (1988), we found the excitation classes are not uniformly distributed. A clear peak at about classes 5 and 6 is noticed. The distribution is shifted toward a lower excitation range with respect to that of the nearby nebulae, reflecting the difference in the central star temperature distribution between the two samples.

The abundances of the planetary nebulae (PNe) in the galactic bulge are presented. Comparisons are made with the disk nebulae, the solar values, and the prediction based on the observed gradients in the disk. The mean abundances in the bulge PNe cannot be predicted by the observed gradient in the disk sample. Except for helium and nitrogen, which are systematically higher in the bulge, all other elements show distributions similar to their counterparts in the disk PNe. The relatively older age of the bulge objects suggests a much faster enhancement in the bulge. The significantly higher mean N/O ratio in the bulge PNe compared to the disk PNe, is caused by the much larger fraction of low abundance nebulae with a high N/O ratio in the bulge, rather than by having -on average- more massive progenitors. This is argued since the low abundance is noticed not only in the case of oxygen, which could be largely reduced if we allow for a more intensive ON-cycle to occur, but also in the cases of neon, sulfur, and argon - the elements which are believed to be essentially untouched by the nucleosynthesis in the PN progenitors. Several lines of evidence strongly argue that in the bulge, the production rates of elements and isotopes mostly produced in low and intemediate stars relative to those of elements mainly produced in massive stars, are higher than the corresponding ratios in the solar neighbourhood or in other positions in the disk. This probably indicates an initial mass function in the bulge which is different from that in the rest of the Galaxy. An evolutionary scenario for the bulge, allowing for a more efficient star formation and a much shorter timescale to collapse than in the disk, with an initial mass function such that the fraction of massive stars is lower than in the solar neighbourhood, is then proposed to explain the exisiting data.

The abundances of the planetary nebulae (PNe) in the galactic bulge are presented. Comparisons are made with the disk nebulae, the solar values, and the prediction based on the observed gradients in the disk. The mean abundances in the bulge PNe cannot be predicted by the observed gradient in the disk sample. Except for helium and nitrogen, which are systematically higher in the bulge, all other elements show distributions similar to their counterparts in the disk PNe. The relatively older age of the bulge objects suggests a much faster enhancement in the bulge. The significantly higher mean N/O ratio in the bulge PNe compared to the disk PNe, is caused by the much larger fraction of low abundance nebulae with a high N/O ratio in the bulge, rather than by having -on average- more massive progenitors. This is argued since the low abundance is noticed not only in the case of oxygen, which could be largely reduced if we allow for a more intensive ON-cycle to occur, but also in the cases of neon, sulfur, and argon - the elements which are believed to be essentially untouched by the nucleosynthesis in the PN progenitors. Several lines of evidence strongly argue that in the bulge, the production rates of elements and isotopes mostly produced in low and intemediate stars relative to those of elements mainly produced in massive stars, are higher than the corresponding ratios in the solar neighbourhood or in other positions in the disk. This probably indicates an initial mass function in the bulge which is different from that in the rest of the Galaxy. An evolutionary scenario for the bulge, allowing for a more efficient star formation and a much shorter timescale to collapse than in the disk, with an initial mass function such that the fraction of massive stars is lower than in the solar neighbourhood, is then proposed to explain the exisiting data.