I present numerical simulations of intensity and degree of polarization of light reflected by Earth-like exoplanets. The results are presented as a function of wavelength, and for a few different phase angles and a few different points on the planet. At this stage the aim is to show the working code and test a few different set ups of the star-planet system in order to find preferable configurations for observations. Not surprisingly, phase angle 90◦ shows the largest degree of polarization. For beneficial wavelength regions, visual light shows a larger overall degree of polarization, while NIR shows very clear absorption patterns in the degree of polarization, making detection of the atmospheric composition possible.

Made available in DSpace on 2014-12-17T15:15:00Z (GMT). No. of bitstreams: 1 JulianaCS_DISSERT.pdf: 3176095 bytes, checksum: 698fc04621ae821b481850e332892a95 (MD5) Previous issue date: 2011-11-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Since Michel Mayor and his student Didier Queloz s pioneer announcement, in 1995, of the existence of a planet orbiting the star 51 Peg, up to present date, 695 extrasolar planets orbiting stars of spectral type F, G, K and M have been discovered. A study on the behavior of the total angular momentum of the planetary systems known up to present date becomes relevant when we know that about 98% of the angular momentum of the solar system is associated with the planets, although they represent only 0.15 percent of the mass of the whole system. In this dissertation we study the behavior of stellar angular momentum, orbital angular momentum and total angular momentum in a sample of 282 stars harboring planets, including 40 multiple systems. We observed that planetary systems containing more than one known planet have both higher orbital angular momentum and total angular momentum compared to those who have only one planet. This analysis shows that multiplanet systems tend to have higher momenta, suggesting that the planets in such systems that contribute to the greater portion momenta have been found. Thus, planetary systems with lower values for the momenta represent the best candidates to the discovery of new planets / Desde o anuncio pioneiro de Michel Mayor e seu ent?o estudante Didier Queloz, em 1995, da exist?ncia de um planeta orbitando a estrela 51 Peg, at? a presente data, 695 planetas extrasolares foram descobertos, orbitando estrelas do tipo espectral F, G, K e M. Um estudo sobre o comportamento do momentum angular total dos sistemas planet?rios, conhecidos at? o momento, torna-se relevante quando conhecemos que cerca de 98% do momentum angular do Sistema Solar est? associado aos planetas, embora esses representem apenas 0,15% da massa de todo o Sistema. Na presente disserta??o de mestrado estudamos o comportamento do momentum angular estelar, do momentum angular orbital e do momentum angular total numa amostra de 282 estrelas, abrigando planetas, incluindo 40 sistemas multiplos. Observamos que os sistemas planet?rios contendo mais de 1 planeta conhecido possuem tanto momentum angular orbital quanto momentum angular total mais elevado, comparado ?queles sistemas que possuem apenas 1 planeta. Esta an?lise mostra que sistemas planet?rios m?ltiplos tendem a ter momenta mais elevado, sugerindo que em tais sistemas os planetas que contribuem com maior parcela para o momenta j? foram descobertos. Sendo assim, sistemas planet?rios com menores valores para o momenta representam melhores candidatos para a descoberta de novos planetas

This thesis is concerned with various aspects of the detection and characterisation of transiting extra-solar planets. The noise properties of photometric data from SuperWASP, a wide-field survey instrument designed to detect exoplanets, are investigated. There has been a large shortfall in the number of planets such transit surveys have detected, compared to previous predictions of the planet catch. It has been suggested that correlated, or red, noise in the photometry is responsible for this; here it is confirmed that red noise is present in the SuperWASP photometry, and its effects on planet discovery are quantified. Examples are given of follow-up photometry of candidate transiting planets, confirming that modestly-sized telescopes can rule out some candidates photometrically. A Markov-chain Monte Carlo code is developed to fit transit lightcurves and determine the depth of such lightcurves in different passbands. Tests of this code with transit data of WASP-3 b are reported. The results of a search for additional transiting planets in known transiting planetary systems are presented. SuperWASP photometry of 24 such systems is searched for additional transits. No further planets are discovered, but a strong periodic signal is detected in the photometry of WASP-10. This is ascribed to stellar rotational variation, the period of which is determined to be 11.91 ± 0.05 days. Monte Carlo modelling is performed to quantify the ability of SuperWASP to detect additional transiting planets; it is determined that there is a good (> 50 per cent) chance of detecting additional, Saturn-sized planets in P ~ 10 day orbits. Finally, the first-ever attempt to detect the secondary eclipse of a transiting extra-solar planet at radio wavelengths is made. Although no eclipse is conclusively detected, upper limits to the flux density from HD 189733 b are established, and compared to theoretical predictions of the flux due to electron-cyclotron maser emission.

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.