Four regions of massive star formation in the Large Magellanic Cloud (LMC) were observed for water and methanol maser emission and radio continuum emission. A total of 42 radio detections were made including 27 new radio sources, four water masers, and eight compact HII regions. The lobes of a radio galaxy were resolved for the first time, and the host galaxy identified. Seven sources were associated with known massive young stellar objects (YSOs). A multi-wavelength analysis using both the infrared and radio spectrum was used to characterize the sources. Mid-infrared color-magnitude selection criteria for ultracompact HII (UCHII) regions in the LMC are presented, yielding 136 UCHII region candidates throughout that galaxy. New maser detections identified two previously unknown massive YSOs. No methanol masers were detected, consistent with previous studies and supporting the hypothesis that the LMC may be deficient in these molecules. These discoveries contribute to the history of star formation in the LMC, which will lead to a better understanding of star formation in the Milky Way and throughout the universe.

No description available.

This thesis presents 1.3 mm and 3.1 mm continuum maps of seven star forming regions within the Large Magellanic Cloud (LMC) as observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). The data were taken as part of six projects retrieved from the ALMA public archive plus one project observed specifically for this work. We developed a technique to combine Band 3 and Band 6 maps to estimate dust-only emission corrected for free-free emission contamination. We also present an automated \texttt{clean} masking script, with a listing of the code, which we adapted and used for all of the imaging in this thesis. From these observations we identify 32 molecular clumps in the LMC and estimate their total mass from their dust emission. We derive a cumulative clump mass function ($N(\geq M) \propto M^{\alpha+1}$) and fit it with a double power law to find $\alpha_{\mathrm{low}} = -1.76^{+0.07}_{-0.1}$, $\alpha_{\mathrm{high}} = -3.3^{+0.3}_{-0.6}$, and a break mass of $2500^{+700}_{-300}$ M$_{\odot}$. Comparing to the clump mass function derived by Indebetouw et al. (2013) from carbon monoxide spectral line emission for 30 Doradus-10 shows a consistent mass range of clumps between 205 $\mathrm{M}_{\odot}$ and 5740 $\mathrm{M}_{\odot}$ as well as consistency between their single power law fit and our low mass power law index. Also comparing to core and clump mass functions from several star forming regions in the Milky Way we find consistency between most of their high mass indices and our low mass index, which is where the clump mass ranges overlap. / Thesis / Master of Science (MSc)

A Pequena Nuvem de Magalhães (PNM) é uma galáxia irregular e rica em gás, que juntamente com a Grande Nuvem de Magalhães (GNM) orbita a Via Láctea (VL). Elas formam um sistema triplo em constante interação. A PNM possui metalicidade baixa, e consequentemente seu meio interestelar (MI) apresenta propriedades particularmente diferentes das observadas para o MI da Galáxia. Mais do que isso, a importância do campo magnético em escalas galácticas vem sendo evidenciada cada vez mais. Então, o objetivo desta dissertação foi estudar a estrutura do campo magnético na PNM, e sua relação com componentes do MI desta galáxia. Para este fim, utilizamos dados de polarimetria no óptico, obtidos no Cerro Tololo Inter American Observatory. Construímos um catálogo polarimétrico que contém 7.207 estrelas em 28 campos distribuídos nas secções Nordeste e da Asa da PNM. Os mapas de polarização traçam o campo magnético no plano do céu diretamente, e pode-se obter sua intensidade utilizando o método de Chandrasekhar & Fermi. A partir do catálogo polarimétrico gerado neste trabalho, conseguimos observar que o campo magnético na PNM possui direção bastante irregular, porém é provável a existência de dois padrões em larga escala o primeiro alinhado com a Ponte pan-Magelânica e o segundo alinhado com a Barra da PNM. Obtivemos para o campo magnético regular Bcéu = (1,84 ± 0,11) uG e para o campo turbulento dB = (2,920 ± 0,098) uG. Esse resultado evidencia que na PNM o campo aleatório domina com relação ao de larga escala, justificando a observação de uma configuração tão irregular para os vetores de polarização. Correlacionando os mapas de polarização com estruturas presentes no MI da PNM, pudemos verificar a presença de diversos shells que podem possuir campos magnéticos da ordem de algumas dezenas de uG. Também foi possível observar ambientes onde o campo regular parece ter sido destruído pela turbulência e outros onde ele pode ainda não ter tido tempo de se formar. Derivamos a relação entre polarização e avermelhamento, e obtivemos como resultado que ela é da ordem de P/Av ~ 2, o que indica que na PNM a eficiência para polarização pode ser menor do que na Galáxia, talvez devido a alta turbulência e/ou ao fato de que nela o campo regular é muito baixo. Por fim, a partir da estimativa para as densidades de energia do campo magnético e para o movimento de rotação e de turbulência do gás, pudemos mostrar que o campo magnético possui importância dinâmica para PNM, sendo a componente turbulenta a maior responsável pela pressão magnética. / The Small Magellanic Cloud (SMC) is a gas rich irregular galaxy which, together with the Large Magellanic Cloud (LMC), orbit the Milky Way (MW). They form a triple system in constant interaction. The SMC is a metal poor galaxy and, due to this, its interstellar medium (ISM) presents different properties from the Galaxy\'s ISM. In addition to that, the importance of magnetic fields on galactic scales is being recognized nowadays. Therefore, the aim of this project was to study the magnetic field structure of the SMC and its relationship with other components of SMC\'s ISM. For this purpose we have used starlight optical polarimetric data, obtained at Cerro Tololo Inter-American Observatory. We have constructed a polarization catalog containing a total of 7,207 stars in 28 fields in the Northeast/Wing sections of the SMC. The polarimetric vector maps trace the ISM magnetic field component in the plane of the sky and one can estimate its intensity towards a given region using the Chandrasekhar & Fermi method. Making use of the polarimetric catalog from this work, we have found that the magnetic field in the SMC, although varying from region to region, nevertheless shows two large scale patterns - the first one aligned with the Magellanic Bridge and a second one aligned with the SMC\'s Bar. We derived for the regular sky-projected magnetic field a value of Bsky = (1.84 ± 0.11) uG, and for the turbulent magnetic field dB = (2.920 ± 0.098) uG. These results evidence that in the SMC the random field prevails over the large scale field, which explains the irregular configuration of the polarization vectors often seen. Correlating the polarization maps with structures present on the SMC\'s ISM, we could identify the presence of several shells which may have magnetic fields up to a few tens uG. It was also possible to observe environments where the regular field seems to have been destroyed due to turbulence, and others where it seems that the large scale magnetic field has not enough time to be formed. Studying the relationship with polarization and reddening, we have obtained a value for P/Av ~ 2, which may indicate that the polarization efficiency in the SMC is smaller than in the Galaxy, perhaps due to a higher turbulence and/or because of a smaller regular magnetic field. Lastly, we have estimated the energy density for the magnetic field and for the rotation and turbulent gas motions. We showed that the magnetic field is dynamically important in the SMC\'s ISM, and that the turbulent component is the largest contributor to the magnetic pressure.

A Pequena Nuvem de Magalhães (PNM) é uma galáxia irregular e rica em gás, que juntamente com a Grande Nuvem de Magalhães (GNM) orbita a Via Láctea (VL). Elas formam um sistema triplo em constante interação. A PNM possui metalicidade baixa, e consequentemente seu meio interestelar (MI) apresenta propriedades particularmente diferentes das observadas para o MI da Galáxia. Mais do que isso, a importância do campo magnético em escalas galácticas vem sendo evidenciada cada vez mais. Então, o objetivo desta dissertação foi estudar a estrutura do campo magnético na PNM, e sua relação com componentes do MI desta galáxia. Para este fim, utilizamos dados de polarimetria no óptico, obtidos no Cerro Tololo Inter American Observatory. Construímos um catálogo polarimétrico que contém 7.207 estrelas em 28 campos distribuídos nas secções Nordeste e da Asa da PNM. Os mapas de polarização traçam o campo magnético no plano do céu diretamente, e pode-se obter sua intensidade utilizando o método de Chandrasekhar & Fermi. A partir do catálogo polarimétrico gerado neste trabalho, conseguimos observar que o campo magnético na PNM possui direção bastante irregular, porém é provável a existência de dois padrões em larga escala o primeiro alinhado com a Ponte pan-Magelânica e o segundo alinhado com a Barra da PNM. Obtivemos para o campo magnético regular Bcéu = (1,84 ± 0,11) uG e para o campo turbulento dB = (2,920 ± 0,098) uG. Esse resultado evidencia que na PNM o campo aleatório domina com relação ao de larga escala, justificando a observação de uma configuração tão irregular para os vetores de polarização. Correlacionando os mapas de polarização com estruturas presentes no MI da PNM, pudemos verificar a presença de diversos shells que podem possuir campos magnéticos da ordem de algumas dezenas de uG. Também foi possível observar ambientes onde o campo regular parece ter sido destruído pela turbulência e outros onde ele pode ainda não ter tido tempo de se formar. Derivamos a relação entre polarização e avermelhamento, e obtivemos como resultado que ela é da ordem de P/Av ~ 2, o que indica que na PNM a eficiência para polarização pode ser menor do que na Galáxia, talvez devido a alta turbulência e/ou ao fato de que nela o campo regular é muito baixo. Por fim, a partir da estimativa para as densidades de energia do campo magnético e para o movimento de rotação e de turbulência do gás, pudemos mostrar que o campo magnético possui importância dinâmica para PNM, sendo a componente turbulenta a maior responsável pela pressão magnética. / The Small Magellanic Cloud (SMC) is a gas rich irregular galaxy which, together with the Large Magellanic Cloud (LMC), orbit the Milky Way (MW). They form a triple system in constant interaction. The SMC is a metal poor galaxy and, due to this, its interstellar medium (ISM) presents different properties from the Galaxy\'s ISM. In addition to that, the importance of magnetic fields on galactic scales is being recognized nowadays. Therefore, the aim of this project was to study the magnetic field structure of the SMC and its relationship with other components of SMC\'s ISM. For this purpose we have used starlight optical polarimetric data, obtained at Cerro Tololo Inter-American Observatory. We have constructed a polarization catalog containing a total of 7,207 stars in 28 fields in the Northeast/Wing sections of the SMC. The polarimetric vector maps trace the ISM magnetic field component in the plane of the sky and one can estimate its intensity towards a given region using the Chandrasekhar & Fermi method. Making use of the polarimetric catalog from this work, we have found that the magnetic field in the SMC, although varying from region to region, nevertheless shows two large scale patterns - the first one aligned with the Magellanic Bridge and a second one aligned with the SMC\'s Bar. We derived for the regular sky-projected magnetic field a value of Bsky = (1.84 ± 0.11) uG, and for the turbulent magnetic field dB = (2.920 ± 0.098) uG. These results evidence that in the SMC the random field prevails over the large scale field, which explains the irregular configuration of the polarization vectors often seen. Correlating the polarization maps with structures present on the SMC\'s ISM, we could identify the presence of several shells which may have magnetic fields up to a few tens uG. It was also possible to observe environments where the regular field seems to have been destroyed due to turbulence, and others where it seems that the large scale magnetic field has not enough time to be formed. Studying the relationship with polarization and reddening, we have obtained a value for P/Av ~ 2, which may indicate that the polarization efficiency in the SMC is smaller than in the Galaxy, perhaps due to a higher turbulence and/or because of a smaller regular magnetic field. Lastly, we have estimated the energy density for the magnetic field and for the rotation and turbulent gas motions. We showed that the magnetic field is dynamically important in the SMC\'s ISM, and that the turbulent component is the largest contributor to the magnetic pressure.

The physics pertaining to the asymptotic giant branch (AGB) phase of stellar evolution has been studied for many years. However, the mechanics behind many characteristics displayed at this stage are still not fully understood. As a member of the Long Period Variable class of stars, AGB stars are invaluable in creating three-dimensional maps of the Milky Way, the Magellanic System and other galaxies with resolved stellar populations. Variable stars can be used to determine radial distances from Earth using their periodic luminosity variations. As this type of star has unknown qualities, models of AGB populations need to be calibrated with observed data. Previous research has derived a best-fitting model using the TRILEGAL code (a TRIdimensional modeL of thE GALaxy). This model was calibrated against single-epoch luminosity functions (LFs) calculated from resolved stellar populations in the Small Magellanic Cloud (SMC). With multi-epoch data now available from the VISTA survey of the Magellanic Clouds (VMC), this best-fitting model can now be compared with the LFs as they vary with time. Firstly, statistical tests are completed to measure the extent of the LF variation between epochs and from the mean LF for both the full VMC AGB catalogue and for the oxygen-rich, carbon-rich and extreme AGB classes. Statistical tests are then performed to measure the similarity between the LFs from different epochs and the simulated LFs, again for the entire sample and the three classes. This investigation shows that, while the current best-fitting model is a good approximation of many individual epochs’ AGB LFs in the SMC to within 3σ, inclusion of multi-epoch data would make for a more robust analysis. In order to do this, it would be desirable to have more epochs with deeper and regular observations that could cover full lightcurves of some of the sources. There also seems to be a statistical difference between the inner and outer areas of the SMC, perhaps due to tidal disruptions. It would be interesting to see the results of a similar study using the LMC, which is less affected by the gravitational influence of its smaller companion. / <p>This thesis was written under the supervision of Maria-Rosa Cioni at the Leibniz Institute for Astrophysics in Potsdam. The presentation was held online due to the COVID-19 pandemic.</p>

In this paper, we introduce the Local Volume TiNy Titans sample (LV-TNT), which is a part of a larger body of work on interacting dwarf galaxies: TNT . This LV-TNT sample consists of 10 dwarf galaxy pairs in the Local Universe (< 30 Mpc from Milky Way), which span mass ratios of M-*,M- 1/M-*,M- 2 < 20, projected separations < 100 kpc, and pair member masses of log(M-*/M-aS (TM)) < 9.9. All 10 LV-TNT pairs have resolved synthesis maps of their neutral hydrogen, are located in a range of environments and captured at various interaction stages. This enables us to do a comparative study of the diffuse gas in dwarf-dwarf interactions and disentangle the gas lost due to interactions with haloes of massive galaxies, from the gas lost due to mutual interaction between the dwarfs. We find that the neutral gas is extended in the interacting pairs when compared to non-paired analogues, indicating that gas is tidally pre-processed. Additionally, we find that the environment can shape the H i distributions in the form of trailing tails and that the gas is not unbound and lost to the surroundings unless the dwarf pair is residing near a massive galaxy. We conclude that a nearby, massive host galaxy is what ultimately prevents the gas from being re-accreted. Dwarf-dwarf interactions thus represent an important part of the baryon cycle of low-mass galaxies, enabling the 'parking' of gas at large distances to serve as a continual gas supply channel until accretion by a more massive host.

The next generation of ground-based optical/infrared (IR) telescopes will have primary mirrors of up to 42 m. To take advantage of the large potential increase in angular resolution, adaptive optics will be essential to overcome the resolution limits set by atmospheric turbulence. Novel techniques such as Multi-Conjugate Adaptive Optics (MCAO) and Multi-Object Adaptive Optics (MOAO) are being developed to achieve near diffraction-limited images over large fields-of-view. This thesis concerns the development of MCAO and MOAO pathfinders. Specifically, the construction of CANARY, aMOAO demonstrator, and the on-sky performance and scientific exploitation of the Multi-conjugate Adaptive optics Demonstrator (MAD). CANARY is under construction for the William Herschel Telescope (WHT) in La Palma and contains a telescope simulator to allow testing of the set-up in the laboratory. The simulator contains a natural guide star emulator, turbulence phase screens, and telescope relay optics. The work presented here concerns the integration of the various components in relation to numerical models and the CANARY specifications. MAD was a near-IR imager on the Very Large Telescope (VLT) in Chile. Science demonstration observations were taken of R136, the young, massive cluster situated in the 30 Doradus star-forming region in the Large Magellanic Cloud. These data were used here to determine the MCAO performance across the ~1’x1’ field-of-view, for different pointings with respect to the guide stars, finding high Strehl ratios and relatively uniform corrections across the fields. The MAD data are then used to construct radial surface brightness profiles for R136, providing new insights into intriguing past results from the Hubble Space Telescope. The MAD data reveal that the profile is strongly asymmetric, removing the need for dramatic dynamical evolution of the cluster in the recent past, and highlighting the importance of considering asymmetries when analysing clusters further afield. The MAD data, combined with other near-IR imaging from the VLT, are then used to investigate the nature of candidate young stellar objects from recent observations with the Spitzer Space Telescope.

We examine a diffuse emission region near the center of SNR 0509-67.5 to determine its nature. Within this diffuse region we observe a point-like source that is bright in the near-IR, but is not visible in the B and V bands. We consider an emission line observed at 6766 angstrom and the possibilities that it is Ly alpha, H alpha, and [O II] lambda 3727. We examine the spectral energy distribution (SED) of the source, comprised of Hubble Space Telescope B, V, I, J, and H bands in addition to Spitzer/IRAC 3.6, 4.5, 5.8, and 8 mu m bands. The peak of the SED is consistent with a background galaxy at z approximate to 0.8 +/- 0.2 and a possible Balmer jump places the galaxy at z approximate to 0.9 +/- 0.3. These SED considerations support the emission line's identification as [O II] lambda 3727. We conclude that the diffuse source in SNR 0509-67.5 is a background galaxy at z approximate to 0.82. Furthermore, we identify the point-like source superposed near the center of the galaxy as its central bulge. Finally, we find no evidence for a surviving companion star, indicating a double-degenerate origin for SNR 0509-67.5.

Apesar de a monogamia social ser dominante entre as aves, análises genéticas revelaram relações de parentesco inesperadas, evidenciando diferentes estratégias de reprodução, como a paternidade extra-par e o parasitismo de ninho. Espécies de passeriformes estão entre as mais promíscuas, com altas taxas de paternidade extra-par, enquanto em aves marinhas esse comportamento demonstrou ser menos frequente. Pinguins (Família Spheniscidae) compõem um grupo de 18 espécies de aves marinhas pelágicas e que tem em comum a filopatria, fidelidade a um parceiro e intenso cuidado biparental. Portanto, espera-se que apresentem um comportamento estritamente monogâmico e taxas de paternidade extra-par insignificantes. Avaliamos pela primeira vez o sistema reprodutivo dos Pinguins-de-Magalhães através de uma abordagem genética, buscando investigar a existência e frequência de paternidade extra-par e parasitismo de ninho. O parentesco de 88 filhotes de 44 ninhos de uma colônia na Ilha Quiroga (Argentina) foi determinado com base em análises de 9 marcadores microssatélites. Encontramos baixas taxas de parasitismo de ninho (6%), mas altas taxas de paternidade extra-par (31% e 48% dos ninhos com pelo menos 1 filhote extra-par). Entre os dois anos coletados, encontramos uma pequena diferença na incidência de infidelidade (29% em 2010; 32% em 2011), mas não houve relação com as condições climáticas do período de reprodução da espécie. Além disso, apesar da alta taxa de filhotes extra-par, não encontramos diferença significativa na diversidade genética e nem viés da razão sexual secundária. Acreditamos que a alta taxa de paternidade extra-par encontrada possa ter relação com o comportamento reprodutivo em colônia, a densidade populacional, o sincronismo reprodutivo, ou que parte da paternidade que não correspondeu aos pais sociais seja resultado de troca de parceiros antes da definição final dos casais em cada estação reprodutiva. Nosso estudo pode ajudar a melhor entender e caracterizar o sistema reprodutivo dos Pinguins-de-Magalhães e indica que a espécie é socialmente, mas não geneticamente monogâmica. / Despite the social monogamy being dominant among birds, genetic analysis revealed unexpected kinship relations, showing different reproductive strategies, such as extra-pair paternity and brood parasitism. Passerine species are among the most promiscuous, with high extra-pair paternity rates, while in seabirds this behavior is typically rather less frequent. Penguins (Spheniscidae Family) are a group of 18 species of pelagic seabirds that have in common philopatric behavior, faithfulness to one partner and intense biparental care. Therefore, they are expected to have a strictly monogamous behavior and insignificant rates of extra-pair paternity. For the first time, we evaluated the reproductive system of Magellanic Penguins (Spheniscus magellanicus) through genetic analysis in order to investigate the existence and frequency of extra-pair paternity and brood parasitism. The kinship of 88 offspring of 44 nests from a colony on Quiroga Island (Argentina) was determined based on the analyses of 9 microsatellite markers. We found low rates of brood parasitism (6%), but high extra-pair paternity rates (31% and 48% of nests with at least one extra-pair offspring). Between the two years sampled, we found a small difference in the incidence of infidelity (29% in 2010; 32% in 2011), but no connection with the climatic conditions of each breeding season. In addition, despite the high rate of extra-pair offspring, we found no significant difference in the genetic diversity and no bias in the secondary sex ratio. We believe that the high rate of extra-pair paternity found in our study may be a result of their reproductive behavior of nesting in colonies, breeding synchrony, density, or that part of the mismatching paternity is due mate switching. Our study may help to better understand and characterize the reproductive system of Magellanic penguins and indicates that this species is socially but not sexually monogamous.