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Spectrophotometry of the infrared emission of Earth-like Planets / Spectrophotométrie de l'émission infrarouge des exoplanètes telluriquesGómez Leal, Illeana 11 July 2013 (has links)
Le signal thermique d'une exoplanète tellurique est une clé pour caractériser les propriétés physiques et chimiques de son atmosphère. La résolution spectrale, et donc la caractérisation spectrale que nous pouvons réaliser des planètes extrasolaires, est malheureusement très limité, en particulier pour les planètes similaires à la Terre. Dans cette thèse, j'ai étudié la possibilité de caractériser des exoplanètes telluriques par l'analyse de la variabilité de son émission infrarouge. L'émission thermique apparente est en effet modulée par les saisons, la rotation de la planète, le mouvement et la variabilité des nuages, la phase orbitale, et aussi par la présence des satellites naturels.Premièrement, nous avons étudié l' émission thermique de la Terre vue en tant que point-source distante, ainsi que la variabilité et la dépendance du signal de la géométrie d'observation. J'ai modélisé l'émission de la Terre à l'aide des données satellitaires et des données produites par des modèles de circulation général (GCMs) du Laboratoire de Météorologie Dynamique de Paris (LMD), en comparant les deux types de données afin de valider les simulations.Pendant la deuxième partie de mon travail, j'ai utilisé des donnés du GCM pour modéliser des planètes telluriques qui diffèrent de la Terre par seulement un ou deux paramètres tels que: la vitesse de rotation (y compris des planètes synchrones), une surface planétaire entièrement recouverte par la glace ou de l'eau, l'obliquité de l'axe de rotation ou l'excentricité de l'orbite. Pour toutes ces planètes virtuelles, j'ai étudié le climat, déduit les propriétés physiques de la planète, et produit et analysé les signaux intégrés associés à différentes géométries d'observation.La dernière partie de la thèse est un travail préliminaire qui consiste en ne plus considérer l'émission bolométrique mais le signal de bandes spectrales étroites, grâce à une nouvelle génération de GCM. Parce que chaque bande explore un niveau spécifique dans l'atmosphère, l'étude de la variation du spectre en comparant les variabilités photométriques entre les bandes, permet d'étudier la dynamique, la composition, la distribution et l'évolution de l'atmosphère de la planète, ce qui ouvre un champ encore inexploré pour la caractérisation des exoplanètes. / The thermal emission received from a planet is a key to characterize the physical and chemical properties of its atmosphere. The spectral resolution, and therefore the spectral characterization that we can achieve for extrasolar planets is unfortunately very limited in particular for terrestrial planets. In this thesis, we study the possibility to characterize an Earth-like exoplanet by the analysis of the broadband infrared emission variability. The apparent thermal emission is indeed modulated by the seasons, the rotation of the planet, the motion and variability of atmospheric patterns and clouds, the orbital phase, and even the presence of a moon. As a reference case, we have studied the thermal emission of the Earth seen as a distant point-source, as well as the variability and the dependency of the signal on the observation geometry. We have modeled the emission of the Earth using data derived from observations and data produced by a General Circulation Models (GCMs), comparing both types of data in order to validate our simulations.As a second part of our work, we have used the GCM to model Earth-like planets that differ from the Earth by a few parameters such as different rotation rates (including tidally-locked planets), a planetary surface completely covered by ice or water, different obliquities and eccentricities. For all these virtual planets, we have studied the climate derived from the physical properties and the photometric infrared signal associated with them.The last part of the thesis is a preliminary work that no longer consider the bolometric emission but the signal from narrow spectral bands, thanks to a new generation of GCMs. Because each band probes a specific level in the atmosphere, studying how the low resolution spectrum of the planets varies by comparing the photometric variabilities between bands, we can study the dynamics, composition, distribution and evolution of the atmosphere of the planet, which it opens a yet unexplored field for the characterization of exoplanets.
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The Relationship Between a Variable Orbital Eccentricity and Climate on an Earth-Like Planet / Förhållandet mellan en variabel excentricitet och klimat på en jordliknande planetWanzambi, Ellinor January 2019 (has links)
By using climate models based on the Earth’s climate, you can get information about how the climate on exoplanets can look like. ROCKE-3D is a general circulation model based on ModelE2, which is used for simulations of modern and prehistoric Earth’s climate. ROCKE-3D, on the other hand, is used to simulate terrestrial planets both in our solar system and around other stars. The orbital eccentricity affects a planet’s climate, if the eccentricity is high, the planet will be closer to its star certain parts of the year and further away from it for other parts. Because of this, it is interesting to study the eccentricity’s influence on the climate of exoplanets, especially since the boundaries of the habitable zone change. In this report, the climate of an Earth-like planet with varying orbital eccentricity has been investigated using ROCKE-3D. The results show that the annual average temperature increased if the eccentricity increased, even though it was expected to decrease because the planet was further away from its star for longer periods than it was closer. The reason for this was that the ocean dampened the surface temperature drop. The amount of snow and ice was also examined. As eccentricity increased, the ocean ice became thicker and snow accumulated in the northern hemisphere. This can be explained, even though the annual average temperature increased due to the warmer winters, by the fact that the temperature in the summer decreased so much that the snow and ocean ice did not melt away completely and started to accumulate for the years with higher eccentricities.
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Spectroscopic characterization of transiting exoplanets : A study of the possibility to detect atmospheres around exoplanets using SIMPLEWaldén, Pierre, Aronson, Erik January 2011 (has links)
This report describes simulations of observations with the near-infrared high-resolution spectrometer SIMPLE that is proposed to the ESO telescope E-ELT. We simulate M4 and G2 stars with transiting Earth-like planets and the goal is to distinguish spectral features originating from the atmosphere of the exoplanet. Noise levels of different magnitudes are added to the simulations and the minimal signal-to-noise required for detection of the atmosphere is estimated. Our conclusion is that detection of atmospheric features looks promising using this setup.
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