The most intensely star-forming galaxies lie at z ∼ 2 and are thought to be the progenitors of the most massive galaxies today, yet study of this important population has been hampered by vast quantities of dust, making them almost invisible in the optical and ultraviolet (UV) regimes, and by the low sensitivity and angular resolution of many infrared (IR) facilities. Chapter 2 describes the use of the flux and angular extent boost provided by strong gravitational lensing in the detailed study of individual high-redshift dusty star-forming galaxies (DSFGs). The low number density of such systems has been overcome by recent wide area far-infrared (FIR)–mm surveys, and a sample of candidate systems which are bright enough to study with single-dish FIR telescopes are assembled from these surveys. The chapter further describes spectra of these galaxies obtained using the the Spectral and Photometric Imaging REceiver (SPIRE; Griffin et al. 2010) Fourier transform spectrometer (FTS) on board the Herschel Space Observatory (Pilbratt et al. 2010), exploiting the increased flux densities to search for FIR atomic and ionic spectral lines: important coolants of warm gas surrounding star-formation regions. Chapter 3 describes the first “blind” redshift obtained using Herschel, via the detection of [C ii] 158 μm in one of our spectra. Confirmation of this redshift was provided by detection of CO lines with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Plateau de Bure Interferometer (PdBI), and along with multi-wavelength photometric follow-up, allowed a characterisation of the galaxy, indicating both a merger-driven starburst and an active galactic nucleus (AGN) within the system. Chapter 4 describes the first detection of a massive outflow of molecular gas at high-redshift. Stacking five repeat spectra of the Cosmic Eyelash, one of the best-studied strongly lensed DSFGs, one of the massive star-forming clumps is shown to drive this outflow, albeit likely at a velocity lower than that required to become unbound from the hosting gravitational potential well. Chapter 5 describes line measurements and spectral energy distribution (SED) fitting from the full set of spectra and Herschel PACS mini scan maps. The spectra are stacked to search for faint lines, and compared to a detailed interstellar medium (ISM) model to determine average physical properties of the star-forming gas. Photodissociation region (PDR) properties are found to be similar to those derived using other models, however a cosmic ray ionisation rate of 103 times that of the Milky Way, expected in galaxies of this type cannot reproduce the observed line ratios, in particular the low [O i] 63 μm flux. Chapter 6 finally describes the conclusions drawn from the work presented in this thesis and how these data and analysis add to our knowledge and interpretation of high-redshift DSFGs.

La variété de galaxies dans le Groupe Local rend possible l'étude du milieu interstellaire et de la formation d'étoiles dans des conditions différentes de celles trouvées dans la Voie Lactée, tout en conservant une grande résolution spatiale grâce à leur proximité. Nous avons étudié le milieu interstellaire de deux galaxies du Groupe Local, M33 et NGC6822, dont les métallicités sont inférieures d'un facteur 2 à 3 à celle du soleil et qui sont respectivement dix fois et cent fois moins lumineuses que la Voie Lactée. Nos observations de la transition J=2->1 du monoxyde de carbone, avec une résolution suffisante pour résoudre les nuages moléculaires géants, fournissent la première carte du milieu moléculaire de NGC6822 et la cartographie de M33 avec la meilleure combinaison de résolution et de sensibilité. Nous présentons également une cartographie haute résolution du milieu atomique de M33 à partir d'une mosaïque intérférométrique dans la raie à 21cm de l'ensemble du disque de la galaxie. Combinées avec des données allant de l'ultraviolet à l'infrarouge lointain, ces observations permettent l'étude du milieu interstellaire et de la formation d'étoiles à des échelles allant du nuage individuel à la galaxie dans son ensemble. Ces deux objets, chimiquement jeunes, semblent convertir l'hydrogène moléculaire en étoiles plus rapidement que les grandes galaxies spirales comme la Voie Lactée. Est-ce à rapprocher du taux élevé de formation d'étoiles dans les galaxies de l'univers plus jeune (z~0.5-1), également riches en gaz et bleues comme M33 et NGC6822 ? Un soin particulier a été apporté pour tenter de mesurer la masse de dihydrogène, difficile dans ce type d'objet, à l'échelle de la galaxie ainsi qu'à l'échelle du nuage. Une méthode d'identification automatique et de mesure des propriétés physiques des nuages moléculaires géants a permis d'obtenir, dans le cas de M33, le plus grand catalogue de nuage moléculaires dans une galaxie extérieure. Il en résulte que les nuages de M33 et de NGC 6822 ont, en moyenne, une largeur de raie plus faible, pour une taille donnée, que les nuages de la Voie Lactée. Dans M33, la fraction de petits nuages augmente significativement avec le rayon galactocentrique. Au moins un sixième des nuages moléculaires géants ne sont pas associés à de la formation stellaire (détectée) mais nous n'avons pas identifié de caractéristiques physiques particulières pour ces nuages. / The variety of galaxies in the Local Group enables the study of the interstellar medium and star formation under conditions different from those found in the Milky Way, while retaining a good spatial resolution due to their proximity. We have studied the interstellar medium of two Local Group galaxies, M33 and NGC6822, that have metallicities 2 to 3 times less than solar and are respectively 10 and 100 times less luminous than the Milky Way. Our large scale observations of the CO(2-1) transition, with a resolution sufficient to resolve giant molecular clouds, provide the the first molecular gas map of NGC6822 and the M33 map with the best combination of resolution and sensitivity. We also present a high resolution map of the atomic gas from an interferometric mosaic of M33's disk through the 21cm hydrogen line. Combining these observations with data ranging from ultraviolet to far infrared, we study the interstellar medium and star formation on scales ranging from individual clouds to the whole galaxy. These two chemically young objects appear to be converting molecular hydrogen into stars at a faster rate than in large spirals like the Milky Way. Can this be linked to the high star formation rate in galaxies of the earlier universe (z~0.5-1) which were bluer and gas rich like M33 and NGC6822 ? We have taken particular care to try and measure the molecular hydrogen mass, a difficult task in such objects, at the scale both of the galaxy and of the clouds. An automated molecular cloud identification and physical property measurement has been applied to the molecular gas data, yielding, in the case of M33, the largest catalog of giant molecular clouds in an external galaxy. From this catalog, it is found that the M33 molecular clouds have, on average, a smaller line-width, for a given size, than their Galactic counterparts. In M33, the fraction of small clouds increases significantly with the galactocentric radius. At least a sixth of the giant molecular clouds are not associated with detected star formation but we have not identified any particular physical characteristics for these clouds.

In this thesis I present work done on the subject of star formation through the study of infrared dark clouds. We studied the velocity fields in several IRDCs using spectral line mapping. We also performed observations of a high density tracer and its deuterated counterpart. These observations allow me to assess the kinematics of these clouds and the evolutionary state of the observed targets. The sample observed is an important starting point for the search of early and quiescent high-mass regions. We mapped several IRDCs using the 22m ATNF Mopra Telescope in high-density molecular tracers at 3 mm, HNC (1-0) and N2H+ (1-0). We present integrated intensity emission and velocity field maps of these IRDCs. The molecular emission in the maps matches well with the extinction seen in the mid-IR. For an IRDC-complex we see connecting emission in the whole filament. We calculate kinematic distances and masses of the IRDCs. The IRDCs typically display an ordered velocity field within the clouds. The mean velocity gradient of the sample was 0.4 km/s/pc. We show how this velocity gradient can mean gas flows within the cloud into the central regions in order to feed the central cores. We observed 54 cores in IRDCs using N2H+ (1-0) and (3-2) to determine the kinematics of the densest material, where stars will form. We also observed N2D+ (3-2) towards 29 of the brightest peaks to analyze the level of deuteration which is an excellent probe of the quiescent of the early stages of star formation. There were 13 detections of N2D+ (3-2). This is one of the largest samples of IRDCs yet observed in these species. The deuteration ratio in the sources with detected N2D+ (3-2) has a mean of 0.024 and reaches a maximum value of 0.14. For most of the sources the material traced by N2D+ and N2H+ (3-2) still has significant turbulent motions, however three objects show subthermal N2D+ velocity dispersion. Surprisingly the presence or absence of an embedded 70 micron source shows no correlation with the detection of N2D+ (3-2), nor does it correlate with any change in velocity dispersion or excitation temperature. Comparison with recent models of deuteration suggest evolutionary timescales of these regions of several freefall times or less.

This thesis explores the topic of maximum mass stability of neutron stars. The outer structure is detailed and explores nuclear pasta phases, the neutron drip line, and density transitions of matter in the crust and atmosphere layers. Other discussion points include superfluids in the crust and core, vortex roles in neutron stars, and magnetic field effects on the EOS in neutron stars. The inner core is studied in much more detail due to its significant role in EOS. The variety of stars include pion condensate stars, kaon condensate stars, npeu stars, npeu stars with the inclusion of hyperons, quark-hybrid stars, and strange stars. Included with these is a description of nucleon-nucleon, nucleon-nucleon-nucleon interactions, the appearance factors that affect hyperon species, and the formation process of kaons, pions, quarks, and hyperons. The ending EOS are compared with their maximum mass values to determine which ones are likely to limit the mass of neutron stars.

Several different mechanisms leading to the formation of (substituted) naphthalene and azanaphthalenes were examined using theoretical quantum chemical calculations. As a result, a series of novel synthetic routes to Polycyclic Aromatic Hydrocarbons (PAHs) and Nitrogen Containing Polycyclic Aromatic Compounds (N-PACs) have been proposed. On Earth, these aromatic compounds originate from incomplete combustion and are released into our environment, where they are known to be major pollutants, often with carcinogenic properties. In the atmosphere of a Saturn’s moon Titan, these PAH and N-PACs are believed to play a critical role in organic haze formation, as well as acting as chemical precursors to biologically relevant molecules. The theoretical calculations were performed by employing the ab initio G3(MP2,CC)/B3LYP/6-311G** method to effectively probe the Potential Energy Surfaces (PES) relevant to the PAH and N-PAC formation. Following the construction of the PES, Rice-Ramsperger-Kassel-Markus (RRKM) theory was used to evaluate all unimolecular rate constants as a function of collision energy under single-collision conditions. Branching ratios were then evaluated by solving phenomenological rate expressions for the various product concentrations. The most viable pathways to PAH and N-PAC formation were found to be those where the initial attack by the ethynyl (C2H) or cyano (CN) radical toward a unsaturated hydrocarbon molecule led to the formation of an intermediate which could not effectively lose a hydrogen atom. It is not until ring cyclization has occurred, that hydrogen elimination leads to a closed shell product. By quenching the possibility of the initial hydrogen atom elimination, one of the most competitive processes preventing the PAH or N-PAC formation was avoided, and the PAH or N-PAC formation was allowed to proceed. It is concluded that these considerations should be taken into account when attempting to explore any other potential routes towards aromatic compounds in cold environments, such as on Titan or in the interstellar medium.

Os compostos de fósforo apresentam várias implicações em processos atmosféricos e interestelares. Nesta tese, será realizado um estudo ab initio em três diferentes sistemas. (i) Um destes sistemas é o radical PCO. No capítulo três, foi analisado os aspectos conformacionais do radical PCO, sendo avaliado as propriedades moleculares e termodinâmicas da espécie cíclica e das espécies lineares. Entre os isômeros do radical PCO, a espécie i3 (C∞V, 2π) é a mais estável delas, com uma entalpia de formação a 0K de 22.33±2.10 kcal mol-1. Considerando as barreiras de energia, que convergem em direção a espécie i3, elas apresentam valores próximos de 10 kcal mol-1, ao passo que a energia necessária para a isomerização da molécula i3 para outros isômeros é acima de 60 kcal mol-1. Estes valores de energia explicam o fato que, em condições experimentais, foi detectado apenas a espécie i3 (C∞V, 2π). (ii) No capítulo quatro, foi elucidado o mecanismo da reação PH3 +F, assim como foi também caracterizado as propriedades eletrônicas dos intermediários observados nesta reação. Na reação PH3 +F, pode ser observado que, diferente da literatura, dois caminhos são possíveis para esta reação: (a) a reação de abstração de hidrogênio, com a formação dos produtos PH2 e HF, e a reação de adição-eliminação, com a formação das espécies PH2F e H. Analisando a energia eletrônica, é possível observar que a reação de adição-eliminação apresenta uma barreira de energia de 23 kcal mol-1 abaixo da mesma observada para a reação de abstração de hidrogênio. Considerando os intermediários formados na reação PH3 + F, são observados dois tipos de simetria: uma C1 e duas Cs. Além disso, a entalpia de formação em 298K dos intermediários variou de -22.99 to -29.74 kcal mol-1. (iii) No capítulo cinco, foi avaliada a interação da fosfina com diferentes aglomerados de água. Neste capítulo, foi realizada uma análise nos aglomerados PH3-(H2O)n (n=1-8,12,20) e avaliado a estabilidade dos potenciais isômeros, assim como as propriedades moleculares e espectroscópicas dos diferentes isômeros. Nas estruturas PH3-(H2O)n (n=1-8) foi possível observar que os modos vibracionais δ(PH3) e δsym(PH3) apresentaram um deslocamento para o vermelho, ao passo que as freqüências de estiramento simétrico e assimétrico da fosfina apresentaram um deslocamento para o azul. No caso da estrutura PH3(H2O)20, as variações nos modos vibracionais foram similares embora que mais intensas, sendo o mesmo também observado para as respectivas intensidades. Além disso, a energia necessária para o confinamento da fosfina no interior de um aglomerado de água dodecaedro hexagonal variou de -1.81 to -6.38 kcal mol-1. / The phosphorus compounds show several implications to atmospheric and interstellar processes. In this thesis, was performed an ab initio study on three different systems. (i) One of these systems is the PCO radical. In chapter three, was studied the conformation aspects of PCO radicals, which was assessed the molecular and thermodynamic properties of the cyclic and linear species. In PCO species, it was observed that the linear specie i3 (C∞V, 2π) is the most stable one, with the enthalpy formation at 0K of 22.33±2.10 kcal mol-1. Considering the barrier heights, which converge into the direction of i3, they are close to 10 kcal mol-1, while the energy necessary to the isomerization of i3 to other conformations are high than 60 kcal mol-1. These energy values explain the fact that, in experimental conditions, was detected only the i3 (C∞V, 2π) specie. (ii) In chapter four, it was elucidated the mechanism of the PH3 + F reaction, and it was also described the electronic properties of the intermediates observed in this reaction. In the PH3 + F reaction can be seen that, different from the literature, two possible pathways can be observed: (a) the hydrogen abstraction, with the formation of PH2 and HF products, (b) and the addition-elimination route, with the formation of PH2F and H species. Analyzing the electronic energy, can be observed that the barrier energy of the addition-elimination process is 23 kcal mol-1 bellow the hydrogen abstraction route. Considering the intermediates, two different point groups were detected: a C1 and two Cs. In addition, the enthalpy formation at 298K of the intermediates, in the PH3 + F reaction, range from -22.99 to -29.74 kcal mol-1. (iii) In chapter five, it was studied the interaction of phosphine with different water clusters. In this chapter was performed an analysis of the PH3-(H2O)n (n=1-8,12,20) clusters, and evaluated the stability of the potential isomers as also the molecular and spectroscopy aspects of the different species. In the PH3(H2O)n (n=1-8) structures are seen a redshift in the δ(PH3) and δsym(PH3) vibrational modes, while is observed a blueshift from the asymmetric and symmetric stretching frequencies of phosphine. In the case of PH3(H2O)20 structure, the variations in the vibrational modes were similar however more intense, as also in their respective intensities. In addition, the necessary energy to trap phosphine in the interior of an hexagonal dodecahedron water clusters range from -1.81 to -6.38 kcal mol-1.

La formation des étoiles, processus fondamental en astrophysique, résiste toujours à la compréhension. En effet, de nombreux phénomènes interagissent durant les différentes étapes, et ce sur une large gamme d’échelles. Il est donc primordial de comprendre la dynamique du milieu interstellaire, dans lequel les étoiles se forment. En particulier, il est maintenant bien établi que la structure du milieu interstellaire est fortement impactée par des processus de rétroaction de la part des étoiles qui s’y forment. D’une part cette rétroaction limite le taux de formation de nouvelles étoiles, et d’autre part elle est l’un des contributeurs à la morphologie et la dynamique des galaxies : taille du disque, éjection de matière, etc. Ce travail de thèse propose d’étudier numériquement la dynamique du milieu interstellaire, de manière à mettre en évidence l’impact des processus de rétroaction. Le processus principal qui sera étudié est les supernovae, figurant parmi les évènements les plus énergétiques dans le milieu interstellaire. Après l’étude et la modélisation en détail de l’explosion d’une unique supernova dans nuage moléculaire, un modèle numérique incluant formation d’étoiles et rétroaction par supernovae sera présenté et mis en œuvre dans des simulations d’un disque galactique stratifié à l’échelle du kiloparsec. Une extension de ce modèle pour tenir compte du rayonnement ionisant sera proposée. Il est effectivement possible de réguler la formation d’étoiles à l’aide de modèles de rétroaction par les supernovae, mais les résultats précis dépendent de manière significative des détails du schéma mis en œuvre. En utilisant la variante apparaissant comme la plus réaliste, des simulations à haute résolution du milieu interstellaire sont présentées et étudiées. En particulier, il est possible de mettre en évidence des propriétés de la turbulence compressible et magnétisée à l’échelle galactique : variation des spectres de puissance en fonction de l’altitude, alignement spontané de la vitesse et du champ magnétique, effet antagoniste de la rétroaction sur cet alignement et formation de structures. / Star formation, a fundamental process in astrophysics, remains only partially understood. Several processes are known to interact during all the steps over a large range of scales. It is therefore of highest importance to understand the dynamics of the interstellar medium, in which stars form. In particular, it is now well-known that the structure of the interstellar medium is strongly affected by feedback processes emanating from the stars that form in it. On the one hand this feedback limits the rate of formation of new stars, and on the other hand it is one of the main contributors to the shape and dynamics of galaxies: thickness of the disk, matter outflows, etc. This work aims to study numerically the dynamics of the interstellar medium, in order to highlight the impact of stellar feedback processes. The main process that will be studied is supernovae, being among the most energetic events in the interstellar medium. After the study and detailed modeling of the explosion of a single supernova inside a molecular cloud, a numerical model including star formation and supernova feedback will be presented and used in kiloparsec-scale simulations of a stratified galactic disk. An extension of this model will be suggested in order to take into account the ionizing radiation. It is indeed possible to regulate star formation with supernova feedback models, although the precise results strongly depend on the detailed scheme that is implemented. Using the most realistic-looking variant, high-resolution simulations are presented and studied. In particular, it is possible to extract properties of compressible and magnetized turbulence at the galactic scale: variation of the power spectra as a function of altitude, spontaneous alignment between velocity and magnetic field, antagonistic effect of stellar feedback onto this alignment, and structure formation.

Beta Lyrae is a complex binary star system with a 13-day orbital period containing two massive stars that are in the process of mass reversal accretion. The primary star is the higher mass star which is gaining mass from the secondary star. This reversal mass accretion causes gas to build and form a disk around the primary star. The disk is geometrically and optically thick. Previous interferometric studies in Optical and Infrared wavelengths have shown that a bipolar jet exists in the system and suggest that the jet contributes to the H-alpha emission. Meanwhile, other studies have suggested that the disk contributes to the H-alpha emission. We have taken into account various factors to model the emission of H-alpha from Beta Lyrae. The observed profile is double-peaked and varies with orbital phase. We found that the jet produces a single-peak for H-alpha emission. Meanwhile, the disk produces a double-peak for H-alpha emission if it is based on Keplerian motion. We use our model to interpret the observed H-alpha emission variations in the line shape with orbital phase.

Les poussières interstellaires sont des particules solides dont les tailles sont comprises entre le nanomètre et le micron. Bien que représentant une faible proportion en masse du milieu interstellaire, elles jouent un rôle essentiel dans son évolution et de façon générale dans l'évolution des galaxies. Les poussières interstellaires sont observables dans les domaines UV et visible en extinction et de l'infrarouge au submillimétrique en émission. La conduite d'observations astrophysiques conjuguée au développement de modèles numériques de poussières et à l'étude d'analogues de grains en laboratoire permet d'affiner notre connaissance de ces particules solides. En particulier, il existe aujourd'hui de nombreuses preuves d'une évolution des grains dans le milieu interstellaire. Cependant, les processus physiques responsables de cette évolution sont aujourd'hui encore mal connus. Afin de comprendre comment évoluent les grains avec les propriétés physiques, il est nécessaire d'observer les poussières dans différents environnements. Les régions de photodissociation (PDR) sont des zones du milieu interstellaire présentant l'avantage de voir leur champ de rayonnement et leur densité locale varier sur de faibles échelles spatiales (~10- 20 arcsec). De plus, la grande variété de traceurs du gaz permet de contraindre efficacement les conditions physiques dans les PDR. Toutefois, l'émission des grains à l'équilibre thermique dans les PDR, qui domine l’émission dans l’infrarouge lointain, n'était que rarement résolue spatialement. Les instruments PACS et SPIRE, à bord de l'observatoire spatial Herschel, permettent aujourd'hui de disposer d'observations spectro-photométriques entre 70 et 500 µm, dont la résolution spatiale (comprise entre 5 et 35 arcsec) en fait des données idéales pour l'étude de l'évolution des poussières dans les PDR. Nous présentons l'analyse des observations Herschel de trois PDR, la Barre d'Orion, la Tête de Cheval et la NGC 7023 Est, caractérisées par des conditions physiques différentes. En combinant ces données aux observations Spitzer, nous pouvons étudier simultanément l'émission des poussières entre 3.6 et 500 µm à différentes positions de la PDR. Pour cela, des profils d'intensité reliant l'étoile à la PDR sont extraits à chaque longueur d'onde puis comparés spatialement. Un décalage de la position du pic d’émission dû au transfert radiatif est observé : plus la longueur d'onde est grande, plus le pic est éloigné de l'étoile excitatrice. Par contre, la comparaison entre les profils d'intensité observés et ceux calculés à partir d'un code de transfert de rayonnement couplé à un modèle de poussières correspondant aux propriétés du milieu interstellaire diffus révèle des différences liées à une évolution des grains pour chaque PDR étudiée. A la vue des écarts, nous concluons que l'abondance des PAH, plus petite composante de grains interstellaires, est plus faible dans les PDR que dans le milieu diffus suggérant la présence d'un phénomène de photo-destruction et/ou d'agrégation des PAH sur les gros grains dans les PDR. Ceci pourrait être accompagné d'une augmentation d'émissivité des gros grains liée à un mécanisme de coagulation. Les observations Herschel des PDR nous offrent également l'opportunité de nous intéresser aux variations du spectre des grains à l'équilibre thermique avec le rayonnement au travers des PDR. Un ajustement d'une loi de corps noir modifié permet d'extraire une épaisseur optique, une température et un indice spectral des grains. L'étude de ces deux derniers paramètres révèle une anticorrélation confirmant ainsi des travaux précédents. Cependant, la comparaison de la dépendance de la température et de l'indice spectral dans différentes régions montre différents comportements et exclut une dépendance universelle entre ces deux paramètres. Ce résultat ouvre de nouvelles perspectives quant à l'étude de l'évolution des poussières dans le milieu interstellaire. / Interstellar dust grains are nanometre to micrometer-sized particles. Although a weak proportion of the total interstellar mass is at solid state, dust plays a fundamental role in the evolution of the interstellar medium (ISM) and of the galaxy itself. Grains can be observed in the UV and visible wavelength through extinction whereas their emission is in the infrared to sub-millimetre range. Astrophysical observations combined to numerical models and laboratory studies of dust analogues improve our comprehension of the nature and the physics of interstellar grains. For example, evidence of dust evolution in the interstellar medium are now numerous, even if the physical processes responsible of this evolution are still poorly understood. Understanding how grains evolve with physical conditions requires observations of various environments. Photodissociation regions (PDRs) are zones of the ISM where the radiation field and the local density vary on short spatial scales (~10- 20 arcsec). Moreover the many gas tracers offer the opportunity to constraint efficiently the physical conditions within PDRs. Past missions such as ISO and Spitzer allow to study the evolution of dust in the near-Infrared range. At longer wavelengths, where the grains at thermal equilibrium with the radiation dominate the emission, instruments rarely resolved the spatial emission in PDRs. PACS and SPIRE instruments onboard Herschel Space Observatory provide spectro-photometric data between 70 and 500 µm. Their high spatial resolution (from 5 to 35 arcmin) makes these observations ideal for the study of dust evolution in PDRs. We present here an analysis of Herschel observations of three PDRs: the Orion Bar, the Horsehead and NGC 7023 East, characterized by different physical conditions. By combining these data with shorter wavelength observations from Spitzer, we can study the dust emission spectrum from 3.6 to 500 µm at different positions within the PDR. Intensity profiles are extracted along the PDR at each wavelength and spatially compared. We highlight a shift between the position of the emission peak: the longest the wavelength, the furthest the peak from the exciting star. This is a consequence of the radiative transfer in the PDR as shown from a plane parallel transfer code coupled with a dust model. The comparison between the observed and the modelled profiles computed with typical diffuse dust abundances and properties shows differences linked to dust evolution in each studied PDR. These discrepancies between the data and the model indicate a lower Polycyclic Aromatic Hydrocarbon (PAH, the smallest dust component) abundance in the PDR than in the diffuse medium suggesting photo-destruction and/or PAH sticking on larger grains. This could be accompanied by an increase of big grain emissivity linked to coagulation. Herschel's observations of PDR also offer the chance to probe the variations of the grains at thermal equilibrium with the radiation through PDRs. A modified blackbody fit allows to compute an optical depth, a temperature and a dust spectral emissivity index. Those two last parameters are clearly anticorrelated, which confirms previous works. However, comparing the temperature and emissivity index dependence in different regions shows various behaviours, which excludes a universal law between these parameters. This result opens new perspectives in the study of the dust evolution in the interstellar medium.

PILOT (Polarized Instrument for Long wavelength Observation of the Tenuous interstellar medium) est une expérience embarquée en ballon stratosphérique destinée à la mesure de l'émission polarisée de notre galaxie dans le submillimétrique. La charge pointée de PILOT est composée d'un télescope au foyer duquel est placée une caméra embarquant 2048 bolomètres, refroidis à 300 mK, mesurant dans deux bandes spectrales (240 µm et 550 µm) et deux polarisations. La détection de la polarisation est réalisée à l'aide d'un polariseur placé à 45° dans le faisceau, le décomposant en deux composantes polarisées orthogonales chacune détectée par un bloc détecteur, et d'une lame demi-onde rotative. L'Institut d'Astrophysique Spatiale (Orsay, France) est responsable de la réalisation, de l'intégration, des tests et de l'étalonnage spectral de la caméra. Pour cela deux bancs de mesures sont développés, un pour les essais d'imagerie et de polarisation, et un pour l'étalonnage spectral. L'expérimentation permet de valider l'alignement des optiques froides, de caractériser la qualité optique des images, de caractériser les réponses temporelles et en intensité des détecteurs, et de mesurer la réponse spectrale de la caméra. Un modèle photométrique de l'instrument est développé simulant les différentes configurations pour les essais d'étalonnage spectral, d'imagerie en laboratoire, et en vol, ceci afin d'estimer la puissance totale reçue par chaque pixel du détecteur de chaque configuration. Cette puissance totale est issue de l'émission thermique de l'instrument, de l'atmosphère et des sources observées en vol ou de l'environnement du laboratoire. Une campagne de tests a permis de caractériser et d'étalonner la caméra de l'expérience PILOT. Les premières images dans le domaine du submillimétrique ont été révélées, et les premières réponses spectrales mesurées. Suite à la caractérisation et l'étalonnage spectral, la caméra est alignée avec le miroir primaire sur la nacelle CNES pour des caractérisations et des étalonnages en polarisation de l'instrument complet. Le premier vol est prévu pour le milieu de l'année 2014. / The Polarized Instrument for Long wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon borne experiment designed to measure the polarized emission from dust grains in the galaxy in the submillimeter range. The payload is composed of a telescope at the optical focus of which is placed a camera using 2048 bolometers cooled to 300 mK. The camera performs polarized optical measurements in two spectral bands (240 µm and 550 µm). The polarization measurement is based on a cryogenic rotating half-wave plate and a fixed mesh grid polarizer placed at 45° separating the beam into two orthogonal polarized components each detected by a detector array. The Institut d'Astrophysique Spatiale (Orsay, France) is responsible for the design, integration, tests and spectral calibration of the camera. Two optical benches have been designed for its imaging and polarization characterization and spectral calibration. Theses setups allow to validate the alignment of the camera cryogenic optics, to check the optical quality of the images, to characterize the time and intensity response of the detectors, and to measure the overall spectral response. A numerical photometric model of the instrument was developed for the optical configuration during calibration tests (spectral), functional tests (imager) on the ground, and flight configuration at the telescope focus, giving an estimate of the optical power received by the detectors for each configuration. The tests campaign validates the PILOT camera characterization and calibration. It delivered the first submillimeter images and the first spectral responses. Next, the camera will be aligned and integrated with the primary mirror of the telescope on the CNES gondola, for characterization and optical polarization calibration of the complete instrument. The first flight is now planned for mid 2014.