We present the final results from a targeted search for brown dwarfs with unusual near-infrared colors. From a positional cross-match of the Sloan Digital Sky Survey (SDSS), 2-Micron All-Sky Survey (2MASS), and Wide-Field Infrared Survey Explorer (WISE) catalogs, we have identified 144 candidate peculiar L and T dwarfs. Spectroscopy confirms that 20 of the objects are peculiar or are candidate binaries. Of the 420 objects in our full sample 9 are young (less than or similar to 200 Myr; 2.1%) and another 8 (1.9%) are unusually red, with no signatures of youth. With a spectroscopic J-K-s color of 2.58 +/- 0.11 mag, one of the new objects, the L6 dwarf 2MASS J03530419 +0418193, is among the reddest field dwarfs currently known and is one of the reddest objects with no signatures of youth known to date. We have also discovered another potentially very-low-gravity object, the L1 dwarf 2MASS J00133470+1109403, and independently identified the young L7 dwarf 2MASS J00440332+0228112, which was first reported by Schneider and collaborators. Our results confirm that signatures of low gravity are no longer discernible in low to moderate resolution spectra of objects older than similar to 200 Myr. The 1.9% of unusually red L dwarfs that do not show other signatures of youth could be slightly older, up to similar to 400 Myr. In this case a red J - K-s color may be more diagnostic of moderate youth than individual spectral features. However, its is also possible that these objects are relatively metal-rich, and thus have enhanced atmospheric dust content.

This project aims to obtain and interpret the measurements of the mean longitudinal magnetic field of the chemically peculiar star V1148 Ori. To achieve this aim 12 spectropolarimetric observations obtained by the CFHT using the spectropolarimeter ESPaDOnS were used. The method used to extract the magnetic field signatures from the spectra is called least-squares deconvolution. This method yields line-averaged profiles with a high signal-to-noise ratio. These mean line profiles are necessary to compute the mean longitudinal field. Results of the mean longitudinal field measurements were plotted as a function of the rotational phase, and to this, a sinusoidal function describing a dipolar field was fitted. The dipolar field parameters were computed for two different stellar radii. Inconsistent values for the stellar radii were obtained from the literature, and therefore we calculated two values for each of the parameters. For the surface polar field strength, we found BR1 = 17.38±0.30 kG and BR2 = 12.81±0.22 kG. The calculations involving one of the stellar radii gave results more consistent with previous findings. However, the discrepancy in parameter values could not be accounted for by the small uncertainties. So no definite conclusions can be drawn about the dipolar field parameters. Our fit aligns well with our longitudinal field measurements, no clear indication of any significant deviation from our model assumption, which suggests that the mean longitudinal field is consistent with a large-scale dipolar-like structure.

Magnetic fields play a crucial roll in the stellar activity and evolutionof stars. Despite much research there is much that we do notunderstand. Among Ap stars, empirical evidence has suggested a minimumthreshold for the dipolar magnetic field strength of Bp ≈ 300G.This thesis studies the magnetic field of the Ap star EP UMa usingthe oblique rotator model, which is modeling the star’s magnetic fieldas a dipole. The magnetic field was calculated through the StokesV- and I-spectrum emitted by the star. In total 16 observations ofthe Stokes V and I spectrum were used, collected from the spectropolarimeterNARVAL. These spectra were then analysed using the leastsquares deconvolution method, creating average Stokes V and I profiles,through which the magnetic field were calculated. The result ofthis study indicates a magnetic field of EP UMa with polar strengthof 74G ≤ Bp ≤ 196G, which is well below the suggested minimumthreshold.

Dwarf carbon (dC) stars are main-sequence stars with carbon molecular bands (C_2, CN, CH) in their optical spectra. They are an important class of post-mass transfer binaries since, as main-sequence stars, dCs cannot have produced carbon themselves. Rather, the excess carbon originated in an evolved companion, now a white dwarf, and was transferred to the dC. Because of their complex histories, dCs are an excellent sample for testing stellar physics, including common-envelope evolution, wind accretion, mass transfer efficiencies, and accretion spin-up. However, their fundamental properties remain a mystery, and this impedes efforts to use dCs to constrain the evolution of binary systems. Here, I have investigated the observed properties of dCs, both as a population and as individual objects. Using multi-epoch spectroscopy, I constrained the dC binary fraction to be consistent with 100% binarity. The best-fit orbital separation distribution agrees with the few known dC orbital periods, and suggests a bimodal distribution (one sample with mean periods of hundreds of days, the other thousands of days). I also built a set of optical templates to find and classify additional dCs in spectroscopic surveys. Further, I discovered periodic variability in photometry of 34 dCs, dramatically increasing the number of measured periods. This allowed me to investigate mass transfer mechanisms that are likely to be important in the formation of dCs. Interestingly, some of these objects have short periods (P < 2d), indicating they have gone through a common-envelope phase. I explored the implications of these short-period dCs and how they will allow for constraints to be placed on the physics of common-envelope evolution. Finally, I searched for signs of spin-up and activity in dCs using X-ray emission. From this, I found that dCs are consistent with being rapid rotators, similar to what is observed in samples of normal young dwarfs. In summary, this dissertation presents the most extensive set of dC observational properties that has been compiled to date. I have confirmed the binary origin of dCs and linked some to post-common-envelope binaries. My work has provided a firmer foundation for the use of dCs to explore many essential astrophysical phenomena.

Utilizing an interdisciplinary, multi-level perspective analysis this thesis reviews niche- regime-landscape interactions (analogous to the clusters of actors working at the local level of Gotland representing niche; the regime being national governance goals; and the landscape incorporating global level affairs and institutions such as the European Union (EU)) and their (mis)alignments within the biogas/biofertilizer production system of Gotland, Sweden, a small-island case study for energy-food-transportation transition and sustainable destination development. The study analyzes the heterarchical and polycentric development of biogas on Gotland—a socio-technical niche, nested within a larger energy regime and global landscape for transition—developing an understanding of (mis)alignments of pressures interacting on, at, and between the niche-regime- landscape as they combine with the peculiar competencies, as Loorbach describes, “creative minds, strategists, and visionaries” of a cluster of actors working in the food- energy-transport nexus on the island (2010, p. 6). These peculiar competencies, defined in section two, incorporate, and explore trust, storytelling, crisis, agency, cognitive features, influence, orchestration, social learning, perception, emotion, and expectation dynamics, operating within a strategic niche management context meeting goals for the region, as well as national and international goals set by actors such as the EU and Swedish national government. This is further problematized by landscape-level pressures due to crisis. The purpose is to investigate how clusters of actors with different competencies— connected to the socio-technical niche-level of biogas and biofertilizer production on Gotland—are initiating and accelerating real-world, incremental transition for a region, aligned with niche-, regime- and landscape-level pressures. This research will answer what peculiar competencies are required of key cluster actors within the socio-technical niche of biogas production on Gotland, needed to activate a waste management system, aligned with niche-, regime-, and landscape-level pressures. The study identifies a cluster of actors working in the domains of food, energy, and waste recovery on the island. Through semi-structured interviews and informal participant observation the research describes the political economy of socio-technical governance at the local level of Gotland; the soft features of this domain and their socio-cultural foundations; and expressions of necropolitical power, repurposing the hard features of the niche-regime-landscape to accelerate transition. By identifying the frontrunners for energy transition; their peculiar competencies in this small-island context; and what alignments they foster between the niche, regime and the landscape, the work aims to offer innovative and replicable paths to accelerate transition in small-island contexts. By offering a descriptive overview—and prescriptive recommendations for transition in a variety of regional contexts—the research can provide possible recommendations to increase collaborative initiators, coherence, orchestration, and trust, replicable across regions in Sweden, while transitioning transition research.

Le modèle de concordance de la cosmologie moderne repose entre autre sur l'existence de matière dite « noire », matière qui n'intéragirait que gravitationellement et qui ne peut donc pas être observée directement. Les vitesses particulières des galaxies, puisqu'elles tracent le champ de gravité, sont des sondes non-biaisées de la matière dans l'Univers. Ainsi, l'étude de ces vitesses particulières permet non seulement de cartographier l'Univers proche (matière noire comprise), mais aussi de tester le modèle ΛCDM via la vitesse d'expansion de l'Univers et le taux de formation des structures. Observationnellement, la mesure de la vitesse particulière d'une galaxie se fait à partir de la mesure de sa distance, mesure très imprécise pour les données extragalactiques. Mal modélisée, cette incertitude conduit à des analyses biaisées des vitesses particulières, et ainsi détériore la qualité de cette sonde cosmologique. Dans ce contexte, cette thèse s'intéresse aux erreurs systématiques statistiques des analyses de vitesses particulières. D'abord en étudiant puis modélisant ces erreurs systématiques. Ensuite en proposant de nouveaux modèles pour les prendre en compte. En particulier, y est développé un modèle permettant, à partir des mesures de la vitesse de rotation des galaxies, de reconstruire le champ de densité de l'Univers Local. Ce modèle s'appuie sur l'analyse des corrélations de vitesse données par le modèle de concordance, et la modélisation de la relation de Tully-Fisher, qui lie la vitesse de rotation des galaxies à leur luminosté. Le modèle développé est appliqué au catalogue de distances extragalactiques CosmicFlows-3, permettant ainsi une nouvelle cartographie de l'Univers proche et de sa cinématique / The cosmological concordance model relies on the existence of a ≪ dark ≫ matter which hypothetically only interacts through gravity. Hence, the dark matter could not be observed directly with standard techniques. Since they directly probe gravity, peculiar velocities of galaxies are an unbiased tool to probe the matter content of the Universe. They can trace the total matter field and constrain the Local Universe’s expansion rate and growth of structures. The peculiar velocity of a galaxy can only be measured from its distance, which determination is very inaccurate for distant objects. If not correctly modeled, these uncertainties can lead to biaised analyses and poor constraints on the ΛCDM model. Within this context, this PhD studies the systematic and statistical errors of peculiar velocity analyses. First by investigating and modeling these errors. Then by building Bayesian models to include them. In particular, a model of the Local Universe’s velocity field from the observations of the rotational velocity of galaxies is presented. This model relies on the ΛCDM’s peculiar velocity correlations and on a Tully-Fisher relation model. The model has then been applied to the CosmicFlows-3 catalog of distances and provides a new kinematic map of the Local Universe

<p>We present an investigation of the magnetic field geometries and inhomogeneous distribution of chemical elements in the atmospheres of peculiar A and B stars. Our study combines high-quality spectroscopic and spectropolarimetric stellar observations with the development and application of novel techniques for theoretical interpretation of the shapes and variability of stellar line profiles. In particular, we extend the method of Doppler imaging to the analysis of spectra in the four Stokes parameters, making it possible to derive detailed and reliable stellar magnetic maps simultaneously with the imaging chemical inhomogeneities.</p><p>The magnetic Doppler imaging is applied to study of magnetic topologies and distributions of chemical elements in the peculiar stars α² CVn and 53 Cam. We found that the magnetic field geometry of 53 Cam is considerably more complex than a low-order multipolar topology, commonly assumed for magnetic A and B stars. Our Doppler imaging analysis also led to a discovery and study of spots of enhanced mercury abundance in the atmosphere of α And, a star where the presence of a global magnetic field is unlikely.</p><p>The ESO 3.6-m telescope is used to collect unique, very high spectral- and time-resolution observations of rapidly oscillating peculiar A (roAp) stars and to reveal line profile variations due to stellar pulsations. We present a detailed characterization of the spectroscopic pulsational behaviour and demonstrate a remarkable diversity of pulsations in different spectral lines. The outstanding variability of the lines of rare-earth elements is used to study propagation of pulsation waves through the stellar atmospheres and identify pulsation modes. This analysis led to a discovery of a non-axisymmetric character of pulsations in roAp stars.</p><p>Our study of chemical stratification in the atmosphere of the roAp star γ Equ provides a compelling evidence for significant variation of the chemical composition with depth. We find a combined effect of extreme chemical anomalies and a growth of pulsation amplitude in the outermost atmospheric layers to be the most likely origin of the high-amplitude pulsational variations of the lines of rare-earth elements.</p><p>Observations of cool magnetic CP stars are obtained with the ESO Very Large Telescope and are used for empirical investigation of the anomalies in the atmospheric temperature structure. We show that the core-wing anomaly of the hydrogen Balmer lines observed in some cool CP stars can be attributed to a hot layer at an intermediate atmospheric depth.</p>

We present an investigation of the magnetic field geometries and inhomogeneous distribution of chemical elements in the atmospheres of peculiar A and B stars. Our study combines high-quality spectroscopic and spectropolarimetric stellar observations with the development and application of novel techniques for theoretical interpretation of the shapes and variability of stellar line profiles. In particular, we extend the method of Doppler imaging to the analysis of spectra in the four Stokes parameters, making it possible to derive detailed and reliable stellar magnetic maps simultaneously with the imaging chemical inhomogeneities. The magnetic Doppler imaging is applied to study of magnetic topologies and distributions of chemical elements in the peculiar stars α2 CVn and 53 Cam. We found that the magnetic field geometry of 53 Cam is considerably more complex than a low-order multipolar topology, commonly assumed for magnetic A and B stars. Our Doppler imaging analysis also led to a discovery and study of spots of enhanced mercury abundance in the atmosphere of α And, a star where the presence of a global magnetic field is unlikely. The ESO 3.6-m telescope is used to collect unique, very high spectral- and time-resolution observations of rapidly oscillating peculiar A (roAp) stars and to reveal line profile variations due to stellar pulsations. We present a detailed characterization of the spectroscopic pulsational behaviour and demonstrate a remarkable diversity of pulsations in different spectral lines. The outstanding variability of the lines of rare-earth elements is used to study propagation of pulsation waves through the stellar atmospheres and identify pulsation modes. This analysis led to a discovery of a non-axisymmetric character of pulsations in roAp stars. Our study of chemical stratification in the atmosphere of the roAp star γ Equ provides a compelling evidence for significant variation of the chemical composition with depth. We find a combined effect of extreme chemical anomalies and a growth of pulsation amplitude in the outermost atmospheric layers to be the most likely origin of the high-amplitude pulsational variations of the lines of rare-earth elements. Observations of cool magnetic CP stars are obtained with the ESO Very Large Telescope and are used for empirical investigation of the anomalies in the atmospheric temperature structure. We show that the core-wing anomaly of the hydrogen Balmer lines observed in some cool CP stars can be attributed to a hot layer at an intermediate atmospheric depth.

The purpose of this thesis is to define a “local” version of Ozsváth and Szabó’s Heegaard Floer homology HFL^ for links in the 3-sphere, i.e. a Heegaard Floer homology HFT^ for tangles in the 3-ball. The decategorification of HFL^ is the classical Alexander polynomial for links; likewise, the decategorification of HFT^ gives a local version ∇ˢ of the Alexander polynomial. In the first chapter of this thesis, we give a purely combinatorial definition of this polynomial invariant ∇ˢ via Kauffman states and Alexander codes and investigate some of its properties. As an application, we show that the multivariate Alexander polynomial is mutation invariant. In the second chapter, we define HFT^ in two slightly different, but equivalent ways: One is via Juhász’s sutured Floer homology, the other by imitating the construction of HFL^. We then state a glueing theorem in terms of Zarev’s bordered sutured Floer homology, which endows HFT^ with additional structure. As an application, we show that any two links related by mutation about a (2,−3)-pretzel tangle have the same δ-graded link Floer homology. This result relies on a computer calculation. In the third and last chapter, we specialise to 4-ended tangles. In this case, we give a reformulation of HFT^ with a glueing structure in terms of (what we call) peculiar modules. Together with a glueing theorem, we can easily recover oriented and unoriented skein relations for HFL^. Our peculiar modules also enjoy some symmetry relations, which support a conjecture about δ-graded mutation invariance of HFL^. However, stronger symmetries would be needed to actually prove this conjecture. Finally, we explore the relationship between peculiar modules and twisted complexes in the wrapped Fukaya category of the 4-punctured sphere. There are four appendices, some of which might be of independent interest: In the first appendix, we describe a general construction of dg categories which unifies all algebraic structures used in this thesis, in particular type A and type D modules from bordered theory. In the second appendix, we prove a generalised version of Kauffman’s clock theorem, which plays a major role for our decategorified invariants. The last two appendices are manuals for two Mathematica programs. The first is a tool for computing the generators of HFT^ and the decategorified tangle invariant ∇ˢ. The second allows us to compute bordered sutured Floer homology using nice diagrams.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-09-15T21:10:44Z No. of bitstreams: 1 dissertacao1 - F.pdf: 19663712 bytes, checksum: b4d07b5a7a0e8418855eb7151fddc47c (MD5) / Made available in DSpace on 2016-09-15T21:10:44Z (GMT). No. of bitstreams: 1 dissertacao1 - F.pdf: 19663712 bytes, checksum: b4d07b5a7a0e8418855eb7151fddc47c (MD5) Previous issue date: 2016-03-16 / This work shows the development of a graphical interface to reduce spectroscopic observations of peculiar galaxies present in the Catalogue of Southern Peculiar Galaxies and Associations (Arp and Madore 1987). The data have been observed with the Cassegrain spectrograph installed at the 1.6-m telescope of the Observat?rio do Pico dos Dias, Brazil/Laborat?rio Nacional de Astrof?sica ? Minist?rio da Ci?ncia Tecnologia e Inova??o (OOD/LNA-MCTI). The interface is called "PyOPD-Cass". In this project, the tasks present in IRAF package are sequenced together in order to produce calibrated data in flux and wavelength. Thus, the methodology used to reduce spectral data allows the user to quickly and easily insert all the necessary parameters for the spectral reduction process. The material developed in this work, within the concept of "pipeline", has the advantage of minimizing the time in the spectral reduction. As application of the computational process, we show only the spectral reduction to a selected set of 73 peculiar galaxies with emission lines observed over the long-term project carried out in OPD/LNA-MCTI ("Spectroscopic Study of Peculiar Galaxies and associations", OP2012A-009). The scientific results of these active galaxies will be discussed later in another study, already under development. All the development program was conducted in Python, further comprising PyRAF language and PyQt adapter as a basis for the final GUI architecture. / Este trabalho, aplicado na sub?rea de Astronomia Extragal?ctica, apresenta o desenvolvimento de uma interface gr?fica de redu??o de dados espectrais no ?ptico para Gal?xias Peculiares e Associa??es do Cat?logo de Arp e Madore (?A Catalogue of Southern Peculiar Galaxies and Associations?, 1987), que vem sendo observadas com o espectr?grafo Cassegrain instalado no foco f/10 do telesc?pio de 1,60m do OPD/LNA-MCTI (Observat?rio do Pico dos Dias/Laborat?rio Nacional de Astrof?sica ? Minist?rio da Ci?ncia Tecnologia e Inova??o). Denominamos a mesma neste trabalho de ?PyOPD-Cass?. Neste projeto de Computa??o Aplicada, as tarefas de redu??o de dados presentes no IRAF ser?o sequenciadas e agrupadas afim de produzir dados finais calibrados em fluxo e comprimento de onda. Dessa forma, constru?mos uma metodologia otimizada para a redu??o dos dados espectrais, a qual permitir? ao usu?rio a inser??o de maneira f?cil e r?pidade todos os par?metros necess?rios para o processo de redu??o espectral. O material desenvolvido neste trabalho, dentro do conceito de "pipeline", possui a grande vantagem de minimizar o tempo de redu??o espectral em rela??o ao processo empregado atualmente. Como aplica??o do processo computacional desenvolvido neste trabalho, ser? mostrada apenas a redu??oespectral para um conjunto selecionado de 73 gal?xias peculiarescom linhas de emiss?o observadas ao longo do projeto de longo prazo realizado no OPD/LNA-MCTI (?Estudo Espectrosc?pico de Gal?xias Peculiares e Associa??es?, OP2012A-009), de autoria do orientador deste trabalho dissertativo. Todo desenvolvimento de programa??o foi realizado no ambiente Python, integrando ainda a linguagem PyRAF e o adaptador de linguagem PyQT, como base para a arquitetura final da interface gr?fica.