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Carter, Andrew James. "Observation and modeling of extrasolar planets." Thesis, Open University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578669.
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The field of exoplanet research has currently yielded the discovery of 552 planets. This figure includes 132 transiting planets which can be studied in greater detail and have formed the cornerstone of research to characterise the exoplanet population. In particular, such studies seek to analyse the planetary atmospheres, but research has thus far yielded more questions than answers. Exoplanetary atmospheric studies have typically focussed on one planet apiece - complicating any comparative analysis as every result employs different methods and instruments. For a comprehensive, comparative study, a robust and reliable means of reducing and analysing such observations is required, along with a body of data from a single instrument. One such instrument is the Bubble Space Telescope (BST) whose NICMOS (Near Infrared Camera and Multi-Object Spectrometer) instrument has observed the transits of nine extrasolar planets across multiple wavelengths in the near-infrared. A robust pipeline has been developed to reduce all such observations using the fame techniques. This pipeline reduces grism images of an exoplanet host star across a transit event. These exposures are checked for bad pixels, flat fielded and background-subtracted before robust extraction of a transit light curve. This light curve is then detrended to remove systematic noise by application of a new technique developed in this study. Following detrending, the light curve is modelled using a be- spoke MCMC (Markov-Chain Monte-Carlo) algorithm to determine the planetary parameters. A continuum of wavelength-dependent transit light curves is also extracted, detrended and modelled to de- termine the variation in transit depth with wavelength; and .hereby infer the transmission spectrum of the planet's atmosphere. The finished pipeline has been applied to three sets of HST NIC- MOS observations covering the transits of WASP-2b, HD189733b and GJ436b. For each data set, a new set of planetary parameters has been derived and for WASP-2b and HD189733b an atmospheric transmission spectrum extracted. Both spectra show signs of atmospheric haze and molecular absorption, but also evidence of residual systematic noise, complicating analysis.
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Muterspaugh, Matthew Ward. "Binary star systems and extrasolar planets." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34646.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.Includes bibliographical references (p. 121-137).
For ten years, planets around stars similar to the Sun have been discovered, confirmed, and their properties studied. Planets have been found in a variety of environments previously thought impossible. The results have revolutionized the way in which scientists understand planet and star formation and evolution, and provide context for the roles of the Earth and our own solar system. Over half of star systems contain more than one stellar component. Despite this, binary stars have often been avoided by programs searching for planets. Discovery of giant planets in compact binary systems would indirectly probe the timescales of planet formation, an important quantity in determining by which processes planets form. A new observing method has been developed to perform very high precision differntial astrometry on bright binary stars with separations in the range of 0.1 - 1.0 arcseconds. Typical measurement precisions over an hour of integration are on the order of 10 micro-arcseconds (as), enabling one to look for perturbations to the Keplerian orbit that would indicate the presence of additional components to the system. This method is used as the basis for a new program to find extrasolar planets. The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) is a search for giant planets orbiting either star in 50 binary systems. The goal of this search is to detect or rule out planets in the systems observed and thus place limits on any enhancements of planet formation in binaries. It is also used to measure fundamental properties of the stars comprising the binary, such as masses and distances, useful for constraining stellar models at the 10-3 level.
(cont.) This method of differential astrometry is applied to three star systems. Equulei is among the most well-studied nearby binary star systems. Results of its observation have been applied to a wide range of fundamental studies of binary systems and stellar astrophysics. PHASES data are combined with previously published radial velocity data and other previously published differential astrometry measurements to produce a combined model for the system orbit. The distance to the system is determined to within a twentieth of a parsec and the component masses are determined at the level of a percent. n Pegasi is a well-known, nearby triple star system consisting of a "wide" pair with semi-major axis 235 milli-arcseconds, one component of which is a single-line spectroscopic binary (semi-major axis 2.5 milli-arcseconds). Using high-precision differential astrometry and radial velocity observations, the masses for all three components are determined and the relative inclination between the wide and narrow pairs' orbits is found to be 43.8 ± 3.0 degrees, just over the threshold for the three body Kozai resonance. The system distance is determined to a fifth of a parsec, and is consistent with trigonometric parallax measurements. V819 Herculis is a well-studied triple star system consisting of a "wide" pair with 5.5 year period, one component of which is a 2.2-day period eclipsing single-line spectroscopic binary. Differential astrometry measurements from PHASES determine the relative inclination of the short- and long-period orbits. Finally, the prospects for finding planets that simultaneously circle both stars in a binary system are evaluated. Planet searches of this type would represent a complementary investigation to PHASES and contribute similar scientific results.
by Matthew Ward Muterspaugh.
Ph.D.
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Hood, Ben Andrew Ashcom. "Extrasolar planet search and characterisation." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/359.
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Dominis, Dijana. "The role of binary stars in searches for extrasolar planets by microlensing and astrometry." Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2006/1081/.
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Leigh, Christopher. "The detection and characterisation of extrasolar planets." Thesis, University of St Andrews, 2004. http://hdl.handle.net/10023/12943.
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Since the discovery of 51 Pegasi b in 1995, continued observations have indirectly identified over 110 planetary objects. These Jupiter-mass objects cause their host star to "wobble" slightly about the common centre-of-mass of the system, which is detectable as radial motion in high-precision Doppler spectroscopy. Of the known planets, approximately 20% are found to orbit within 0.1 AU of the star, whilst the transit of HD209458 has inferred the gas-giant nature of these close-in extrasolar giant planets (CEGPs). The discovery of CEGPs has produced a wave of speculative theory as to the exact nature of these objects, and how they came to exist so close to their parent star. Our spectroscopic technique provides a method of achieving the direct detection of a CEGP atmosphere, the results of which will allow us to test emerging models that aim to predict the atmospheric nature of CEGPs and may provide additional information on the orbital inclination and mass of the planet. We start with a historical review of the field of extrasolar planets, followed by an introduction to the fundamental concepts which underpin the reflection of starlight from a planet's surface. We then investigate the prospects of detecting such a reflection, before detailing the technique we have devised and applied here to two known CEGP hosts. In the first instance, r Bootis, we combined observations at the 4.2-m William Herschel telescope in 1998, 1999 and 2000. The dataset comprised 893 high-resolution échelle spectra with a total integration time of 75hr 32min spanning 17 nights. We establish an upper limit on the planet's geometric albedo p < 0.39 (at the 99.9% significance level) at the most probable orbital inclination i ~ 36 deg, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp - 1.2RJup. Although a weak candidate signal appears near to the most probable radial velocity amplitude, its statistical significance is insufficient for us to claim a detection with any confidence. In the second instance, HD75289, 4 nights of VLT(UT2)/UVES observations were secured in 2003 Jan, yielding 684 high-resolution spectra with a total integration time of 26 hours. We establish an upper limit on the planet's geometric albedo p < 0.12 (to the 99.9% significance level) at the most probable orbital inclination i ~/= 60 deg, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp = 1.6RJup. In both cases, we are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks.
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Doellinger, Michaela. "Hunting for extrasolar planets around K giants." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-99700.
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Nikku, Madhusudhan 1980. "Retrieval of atmospheric properties of extrasolar planets." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/63006.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 133-137).
We present a new method to retrieve molecular abundances and temperature profiles from exoplanet atmosphere photometry and spectroscopy. Our method allows us to run millions of 1-D atmosphere models in order to cover the large range of allowed parameter space. In order to run such a large number of models, we have developed a parametric pressure-temperature (P-T) profile coupled with line-by-line radiative transfer, hydrostatic equilibrium, and energy balance, along with prescriptions for non-equilibrium molecular composition and energy redistribution. The major difference from traditional 1-D radiative transfer models is the parametric P-T profile, which essentially means adopting energy balance only at the top of the atmosphere and not in each layer. We see the parametric P-T model as a parallel approach to the traditional exoplanet atmosphere models that rely on several free parameters to encompass unknown absorbers and energy redistribution. The parametric P-T profile captures the basic physical features of temperature structures in planetary atmospheres (including temperature inversions), and reproduces a wide range of published P-T profiles, including those of solar system planets. We apply our temperature and abundance retrieval method to two exoplanets which have the best data available, HD 189733b and HD 209458b. For each planet, we compute - 107 atmospheric spectra on a grid in the parameter space, and report contours of the error surface, given the data. For the day-side of HD 189733b, we place constraints on the atmospheric properties based on three different data sets available. Our best-fit models to one of the data sets allow for very efficient daynight energy redistribution in HD 189733b. The different constraints on molecular abundances confirm the presence of H20, CH4 , CO and CO 2 in HD 189733b. Our results also rule out the presence of a thermal inversion in this planet. The model constraints due to the different data sets indicate that the planetary atmosphere is variable, both, in its energy redistribution state and in the chemical abundances. The variability is evident in the data; some key observations with different instruments at the same wavelength differ at the - 2- level. If, on the other hand, the differences in data represent underestimated errors, and if all the data sets have to be reconciled simultaneously, then we are unable to make specific constraints on the molecular abundances or on the temperature profile, beyond identification of molecules and the presence or absence of a thermal inversion. For HD 209458b, we confirm and constrain a thermal inversion in the day-side atmosphere, and the data allows for very efficient day-night redistribution of energy. We report detection of CO, CH4 and CO 2 on the dayside of HD 209458b, along with placing an upper-limit on the amount of H2 0. We also report atmospheric models for three transiting exoplanets with limited data: TrES-2, HAT-P-7b, GJ 436b. For TrES-2 and HAT-P-7b, where only four observations each are available, we find that the data can be fit with models with and without thermal inversions, if we make no assumptions of chemical equilibrium. Finally, in this work, we report the first steps towards developing a parameter estimation procedure for exoplanetary atmospheres. We demonstrate with simulated data that our model can be used with a formal Bayesian parameter estimation algorithm, like MCMC, to place constraints on the atmospheric properties of hot Jupiters.
by Nikku, Madhusudhan.
Ph.D.
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Kipping, D. M. "The transits of extrasolar planets with moons." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1306758/.
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The search for extrasolar planets is strongly motivated by the goal of characterizing how frequent habitable worlds and life may be within the Galaxy. Whilst much effort has been spent on searching for Earth-like planets, large moons may also be common, temperate abodes for life as well. The methods to detect extrasolar moons, or “exomoons” are more subtle than their planetary counterparts and in this thesis I aim to provide a method to find such bodies in transiting systems, which offer the greatest potential for detection. Before one can search for the tiny perturbations to the planetary signal, an understanding of the planetary transit must be established. Therefore, in Chapters 3 to 5 I discuss the transit model and provide several new insights. Chapter 4 presents new analytic expressions for the times of transit minima and the transit duration, which will be critical in the later search for exomoons. Chapter 5 discusses two sources of distortion to the transit signal, namely blending (with a focus on the previously unconsidered self-blending scenario) and light curve smearing due to long integration times. I provide methods to compensate for both of these effects, thus permitting for the accurate modelling of the planetary transit light curve. In Chapter 6, I discuss methods to detect exomoons through their gravitational influence on the host planet, giving rise to transit timing and duration variations (TTV and TDV). The previously known TTV effect is updated with a new model and the associated critical problems are outlined. I then predict a new effect, TDV, which solves these problems, making exomoon detection viable. Chapter 7 presents a feasibility study for detecting habitable-zone exomoons with Kepler, where it is found that moons down to 0.2M⊕ are detectable. Finally, conclusions and future work are discussed in Chapter 8.
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Gaudi, B. Scott. "Microlensing and the search for extrasolar planets /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488199501405399.
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Lewis, Nikole Kae. "Atmospheric Circulation of Eccentric Extrasolar Giant Planets." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242352.
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This dissertation explores the three-dimensional coupling between radiative and dynamical processes in the atmospheres of eccentric extrasolar giant planets GJ436b, HAT-P-2b, and HD80606b. Extrasolar planets on eccentric orbits are subject to time-variable heating and probable non-synchronous rotation, which results in significant variations in global circulation and thermal patterns as a function of orbital phase. Atmospheric simulations for the low eccentricity (e=0.15) Neptune sized planet GJ436b reveal that when Neptune-like atmospheric compositions are assumed day/night temperature contrasts and equatorial jet speeds are significantly increased relative to models that assume a solar-like composition. Comparisons between our theoretical light curves and recent observations support a high metallicity atmosphere with disequilibrium carbon chemistry for GJ436b. The analysis of full-orbit light curve observations at 3.6 and 4.5 microns of the HAT-P-2 system reveal swings in the planet's temperature of more than 900 K during its significantly eccentric (e=0.5) orbit with a four to six hour offset between periapse passage and the peak of the planet's observed flux. Comparisons between our atmospheric model of HAT-P-2b and the observed light curves indicate an increased carbon to oxygen ratio in HAT-P-2b's atmosphere compared to solar values. Atmospheric simulations of the highly eccentric (e=0.9) HD80606b show that flash-heating events completely alter planetary thermal and jet structures and that assumptions about the rotation period of this planet could affect the shape of light curve observations near periapse. Our simulations of HD80606b also show the development an atmospheric shock on the nightside of the planet that is associated with an observable thermal signature in our theoretical light curves. The simulations and observations presented in this dissertation mark an important step in the exploration of atmospheric circulation on the more than 300 exoplanets known to possess significantly non-zero eccentricities.
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Sissa, Elena. "Observation of extrasolar planets at various ages." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3426311.
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The search and characterization of extrasolar planets is one of the main topics of current astronomy, with the ultimate goals of understanding the formation and evolution of planetary systems, the general conditions for the formation of life-friendly environments, and possibly detecting signature of extra-solar life.
In the last decades the research of extrasolar planets underwent a steep increase of interest and different methods of detection were developed.
Each of them has its own merit and lack in studying the extrasolar system architecture and the characteristics of extrasolar planets.
Stars and their planetary entourage form and grow together, at least in most cases, tied by the circumstellar disk.
A unique theory that can describe all the processes that happen between the protostellar cloud collapse and the final system stabilization is not available at the moment. Indirect methods are very useful to study more evolved systems, where the protoplanetary disk contribution is negligible, in their innermost regions.
On the other hand, direct imaging with high-contrast instruments offers the possibility to study the early phases of the planet formation, that are not accessible to other indirect methods of planets detection, and plays a key role in current planet formation theories.
This thesis focuses on the capabilities of direct imaging with SPHERE, the new high-contrast imager of VLT, in detecting planets at different stages of their evolution, coupled with radial velocities observations of old systems obtained from SARG, the old TNG echelle spectrograph.
Chapter 1 briefly introduces the planet formation and evolution theories with the most important exoplanets research methods.
Chapter 2 describes the SPHERE instrument used for the majority of the results presented in this thesis.
In Chapter 3 I present the case of four young objects. I exploit the SPHERE visible channel to study Z CMa jets, and the near-IR channel for HD 100546 and T Cha, looking for the presence of planets. At the same time, I was able to study in detail the circumplanetary disk of HD 100546 in a quite wide spectral range: in the dedicated Section I show that the system brightest structures suggest the presence of at least three gaps in the inner regions of the disk, coupled with other structures, such as spiral arms.
I detected a diffuse source at the location of the claimed planet HD 100546 b, but the nature of this emission is, however, still unknown.
Lastly, LkCa15 was studied both in the visible and in the near-IR of SPHERE.
In Chapter 4 I present the study of the accretion signature in a few objects. GQ Lup b accretion was observed both in H_alpha and in Paschen beta, exploiting all three SPHERE subsystems.
Two systems that have already cleaned out their surroundings from gas and dust are presented in Chapter 5: HIP 80591 and HD 65426. In the latter, I first found out that one companion candidate had high probability to be bound to the star due to its position and it spectral features. These findings were later confirmed by a deeper analysis and follow up observations that demonstrate HD 65426 b, the companion I studied, is a warm Jupiter-like planet with mass between 6 and 12 M_J.
In Chapter 6, I study the chromospheric activity in older binary stars in order to detect a radial velocity signal hidden by the Doppler shift induced by the activity. I found out that Ha-excess, an index based on the Halpha line, is a good indicator of the star activity when the log_RHK' index is not available and can be used also to infer stellar ages in case of stars younger then 1.5 Gyr. Moreover, HD 76073 B shows a high radial velocities scatter that can be explained by the presence of a low-mass companion (Sissa et al. 2016).
Finally, in Chapter 7 I give the conclusions and explain future prospects.
Appendixes are dedicated to the more technical aspects of my work, that were needed to improve instrument capabilities and data reduction, and to better defining the instrument set-ups needed to achieve different scientific aims.La ricerca e la caratterizzazione dei pianeti extrasolari è uno dei maggiori campi di ricerca dell’astronomia attuale, con lo scopo ultimo di capire i meccanismi di formazione e di evoluzione dei sistemi planetari, le condizioni che permettono la formazione di ambienti adatti alla vita, e di trovare le prove di vita extra-solare. Negli ultimi decenni, la ricerca dei pianeti extrasolari ha visto un rapido aumento di interesse, e sono state cosí sviluppate nuove metodologie di ricerca. Ognuna di esse ha aspetti positivi e negativi per lo studio dell’architettura dei sistemi extrasolari e la caratterizzazione dei pianeti. Le stelle e il loro entourage planetario si formano e crescono assieme, per lo meno nella maggioranza dei casi, legate dal disco circumstellare. Al momento manca una teoria universale che possa descrivere tutti i processi che accadono tra le fasi del collasso della nube protostellare e la stabilizzazione finale del sistema. I metodi indiretti sono molto utili per studiare le zone interne dei sistemi più evoluti, nei quali il contributo del disco protoplanetario è trascurabile. Dall’altro lato, la tecnica dell’imaging diretto con strumenti ad alto contrasto offre la possibilità di studiare le prime fasi della formazione planetaria, non accessibili con altri metodi indiretti, e gioca un ruolo fondamentale per le attuali teorie di formazione planetaria. Questa tesi si focalizza sulle capacità dell’imaging diretto ottenuto con SPHERE, il nuovo strumento ad alto contrasto del VLT, nel rivelare pianeti in diversi stadi della loro evoluzione, e presenta uno studio complementare di sistemi vecchi basato sulle osservazioni delle velocità radiali con SARG, il vecchio spettrografo echelle del TNG. Il Capitolo 1 introduce brevemente le teorie di formazione ed evoluzione dei pianeti con i più importanti metodi di ricerca. Il Capitolo \ref{sec:sphere} descrive SPHERE, lo strumento usato per la maggior parte dei risultati presentati in questa tesi. Nel Capitolo 3 presento il caso di quattro oggetti giovani. Ho sfruttato il canale visibile di SPHERE per studiare i jet di Z CMa, e il canale nel vicino infrarosso per HD 100546 e T Cha, cercando segnali della presenza di pianeti. Allo stesso tempo, ho potuto studiare in dettaglio il disco circumstellare di HD 100546 in un intervallo spettrale relativamente ampio: nella sezione ad esso dedicata mostra che le strutture più brillanti del sistema suggeriscono la presenza di almeno tre regioni vuote nelle zone interne del disco, assieme ad altre strutture, come ad esempio bracci a spirale. Ho anche rilevato la presenza di una sorgente diffusa nella posizione attesa per il potenziale pianeta b, ma la natura di questa emissione è, tuttavia, ancora sconosciuta. Infine, LkCa 15 è stato studiato sia nel canale visibile che in quello del vicino infrarosso di SPHERE. Nel Capitolo 4 presento lo studio dei segni distintivi di accrescimento in un gruppo di oggetti. L’accrescimento di GQ Lup b è stato osservato sia in H_alpha che il Paschen beta, sfruttando tutti e tre i sottosistemi di SPHERE. Due sistemi i cui dintorni sono già stati ripuliti dal gas e dalla polvere sono presentati nel Capitolo 5: HIP 80591 e HIP 65426. In quest’ultimo, ho scoperto che uno dei candidati compagni aveva un’alta probabilità di essere legato alla stella a causa della sua posizione e delle sue caratteristiche spettrali. Queste conclusioni sono state poi confermate da un’analisi approfondita e da ulteriori osservazioni che hanno dimostrato che quel compagno, HD 65426 b, è un pianeta gioviano caldo con massa compresa tra 6 e 12 M_J. Nel Capitolo 6, studio l’attività cromosferica in stelle binarie vecchie allo scopo di identificare un segnale nelle velocità radiali nascosto dallo spostamento Doppler indotto dall’attività. Ho scoperto che Ha-excess, un indice basato sulla riga \Ha, è un buon indicatore dell’attività stellare quando l’indice \RHK\ non è disponibile e può essere anche usato per derivare l’età delle stelle nel caso siano più giovani di 1.5 Gyr. Inoltre, HD 76037 B mostra una variazione elevata delle velocità radiali che puo’ essere spiegata con la presenza di un compagno di piccola massa (Sissa et al. 2017) Infine, nel Capitolo 7 fornisco le conclusioni del lavoro ed espongo sviluppi futuri. Le appendici sono dedicate agli aspetti più tecnici del mio lavoro, che sono stati necessari per migliorare le capacità dello strumento e la riduzione dei dati, e per definire al meglio i set-up necessari allo strumento per raggiungere i differenti scopi scientifici.
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Steffen, Jason. "Detecting new planets in transiting systems /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/9686.
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Veras, Dimitri George. "The orbital evolution of extrasolar planets after formation." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273687.
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Wilson, David M. "The search for transiting extrasolar planets with SuperWASP." Thesis, Keele University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443609.
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Koskinen, T. T. "The stability of short-period extrasolar giant planets." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444248/.
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A three-dimensional coupled thermosphere-ionosphere model for extrasolar giant planets (EXOTIM) has been developed. This is the first such model reported in the literature. This thesis contains an extensive description of the model and the methods adopted in modelling the different physical processes expected in the upper atmospheres and ionospheres of extrasolar giant planets. Modelling the upper atmosphere is important because the stability of the atmosphere against thermal evaporation is controlled by the conditions in the thermosphere. The thermosphere is heated by the absorption of EUV and X ray (XUV) radiation emitted by the host star. The radiation also ionises the neutral species in the upper atmosphere, which is expected to be composed mainly of molecular and atomic hydrogen, and atomic helium. Ionisation and subsequent photochemistry leads to the formation of the H+, Hf, H3", and He+ ions (and small quantities of HeH+). H3" emits strongly in the infrared and may act as a significant coolant in gas giant thermospheres. Assuming photochemical equilibrium, the absorption of XUV radiation and ion photochemistry were modelled in a self-consistent fashion. The 3D model can also simulate strong winds affecting the upper atmosphere, and account for both advection and diffusion of the neutral species around the planet. The results indicate that within 1.0 AU from a solar-type host star, the upper atmospheres of Jupiter-type EGPs can be substantially cooler and more stable than implied by studies that ignore the possibility of radiative (Hf) cooling. In this context, a limiting distance, or a stability limit, was identified for such EGPs that depends on the composition of the upper atmosphere and ionosphere, and within which the atmospheres of the planets undergo hydrodynamic escape. Under restricted conditions, this limit is located around 0.15 AU from a Sun-like host star. The model was also used to simulate a newly found transiting planet HD17156b, which orbits its host star on a highly eccentric orbit.
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Mengistie, Getachew Mekonnen. "Gravitational microlensing and the search for extrasolar planets." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/9798.
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Includes bibliographical references.This project is aimed at tackling binary gravitational microlensing events. Since the early conception of gravitational lensing before Einstein’s General Theory of Relativity, physicists and astronomers of the early 18th century speculated that light, if treated as particle, can be affected by gravitational field. Gravitational Microlensing is defined as a phenomenon occurring when light coming from a distant (source) star is bent by the gravitational field of an intervening mass (lens) creating multiple image of the source which cannot be resolved. In this project, We applied a model for binary lens microlensing events. We analysed data obtained from different observatories: PLAXET, which includes SAAO, Sutherland, Canopus and Perth observatories, OGLE, Danish Telescope, LaSilla. For the observed microlensing target OGLE-2011-BLG-265, analysis of the data using the program supplied by Keith Horne, using different minimization schemes and algorithms, I found best fit model to be a binary lens with mass ratio q = 0.0042 and separation of components is found to be u = 1.034 where in this case the separation falls under an intermediate binary lens topology. Finally, the deviation from the point-source point-lens microlensing events on the light curve and small mass ratio suggested a planetary system. I also calculated the time, tp, that the source needs to cross the diameter of the planet Einstein Ring radius, which is related to the mass ratio, and is found to be 3.30 days.
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Safizadeh, Neda. "Detection of extrasolar planets via microlensing and occultation /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3001275.
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Cooper, Curtis Steven. "Meteorologies of Brown Dwarfs and Extrasolar Giant Planets." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195544.
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This dissertation explores the consequences of atmospheric dynamics for observations of substellar mass objects (SMOs). Discussed first is the growth of cloud particles of various compositions in brown dwarfs of different surface gravities and effective temperatures. The structure of these objects is calculated with a one-dimensional radiative transfer model. To determine particle sizes, the timescales for microphysical growth processes, including nucleation, coagulation, and coalescence, are compared to the timescale for gravitational sedimentation. The model also allows for sustained uplifting of condensable vapor in convective regions. The results show that particle sizes vary greatly over the range of objects studied. In most cases, clouds on brown dwarfs do not dominate the opacity. Rather, they smooth the emergent spectrum and partially redistribute the radiative energy. The focus then shifts to extrasolar giant planets (EGPs). Results are presented from a three-dimensional model of atmospheric dynamics on the transiting Jupiter-like planet HD 209458b. As a close-in orbiter (known as a “roaster”), HD 209458b is super-heated on its dayside. Due to tidal locking of the interior, the dayside hemisphere faces the star in perpetuity, which leads to very different dynamics than is seen on Jupiter. The flow is characterized by an eastward supersonic jet (u ∼ 4 km s⁻¹) extending from the equator to the mid-latitudes. Temperature contrasts are ∼ 500 K at the photosphere. At 220 mbar, winds blow the hottest regions downstream from the substellar point by ∼ 60°, with direct implications for the infrared light curve. These simulations are extended to the study of carbon chemistry in HD 209458b’s atmosphere by coupling the CO/CH₄ reaction kinetics to the dynamics. Disequilibrium results from slow reaction rates at low temperatures and pressures. Effective vertical quenching near the ∼ 3 bar level leads to uniformly high concentrations of CO at the photosphere, even in cool regions where CH₄ is strongly favored thermodynamically. Observations are underway to detect these signatures of meteorology on HD 209458b and similar planets.
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Sudarsky, David. "Theoretical spectra and atmospheres of extrasolar giant planets." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280087.
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This work is a detailed study of extrasolar giant planet (EGP) atmospheres and spectra. Models representative of the full range of systems known today are included, from the extreme close-in EGPs to Jovian-like planets at large orbital radii. Using a self-consistent planar atmosphere code along with the latest atomic and molecular cross sections, cloud models, Mie theory treatment of grain scattering and absorption, and incident stellar fluxes, I produce an extensive set of theoretical EGP atmosphere models and emergent spectra. The emergent spectra of EGPs strongly depend upon their outer atmospheric chemical compositions, which in turn depend upon the run of temperature and pressure with atmospheric depth. Because of qualitative similarities in the compositions and spectra of objects within several broad temperature ranges, EGPs fall naturally into five groups, or composition classes. Such a classification scheme, however preliminary, brings a degree of order to the rich variety of EGP systems known to exist today. Generic models that represent the EGP classes, as well as a set of specific models for a number of important systems that have been detected, are provided. Furthermore, the effects on emergent EGP spectra of varying key parameters such as surface gravity, cloud particle sizes, orbital distance, etc. are modeled. A discussion of current and future ground-based and space-based missions to detect and characterize EGPs in light of theoretical spectral models is included to facilitate an understanding of which systems are most likely to be studied successfully.
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Tan, Xianyu, and 谭先瑜. "Characterizing the orbital and dynamical state of extrasolar multiple-planet systems with radial velocity measurements." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50162792.
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Extrasolar planetary surveys have discovered about 780 extrasolar planets and more than 100 multiple planetary systems to date, with the largest fraction of them being confirmed by the radial velocity detection method. Multiple planetary systems, especially those contain pairs of planets in mean-motion resonances, are particularly interesting because their current orbital architectures provide constraints for orbital evolution of planetary systems. Precisely determining the orbital and dynamical state of multiple planetary systems with radial velocity measurements is important.
New results from an analysis of radial velocity data of the HD 82943 planetary system based on 10 years of measurements obtained with the Keck telescope is presented in this thesis. Previous studies have shown that the HD 82943 system has two planets that are likely in 2:1 MMR, with the orbital periods about 220 and 440 days (Lee et al. 2006). However, alternative fits that are qualitatively different have also been suggested, with the two planets in 1:1 resonance or the addition of a third planet possibly in a Laplace 4:2:1 resonance with the other two (Goździewski & Konacki 2006; Beaugé et al. 2008). Here based on the X^2 minimization method combined with parameter grid search, the orbital parameters and dynamical states of the qualitatively different types of fits have been investigated. The results support the coplanar 2:1 MMR configuration for this system and fits of the 1:1 resonance and the 3-planet Laplace resonance are ruled out according to X^2 statistic and dynamical instability. The inclination of the HD 82943 system is well constrained at about 20°C. The system contains two planets with masses of about 4.64 MJ and 4.66 MJ and orbital periods of about 219 and 442 days for the inner and outer planet, respectively. The best fit is dynamically stable with two resonance angles θ 1 = λ1 - 2λ2 + ϖ1 and
θ 2 = λ1 - 2λ2 + ϖ 2 librating around 0°. Based on the best fit, the origin of the 2:1 MMR of the HD 82943 planetary system has been explored by N-body simulations with forced inward migration of the outer planet.
This research has demonstrated the importance of dynamical fitting for multiple planetary systems with radial velocity measurements. It also fulfills the cases of planetary systems in mean-motion resonances such that more generic understanding of the orbital evolution of planetary systems can be obtained.published_or_final_version
Earth Sciences
Master
Master of Philosophy
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Lavvas, P., and T. Koskinen. "Aerosol Properties of the Atmospheres of Extrasolar Giant Planets." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626046.
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We use a model of aerosol microphysics to investigate the impact of high-altitude photochemical aerosols on the transmission spectra and atmospheric properties of close-in exoplanets, such as HD 209458 b and HD 189733 b. The results depend strongly on the temperature profiles in the middle and upper atmospheres, which are poorly understood. Nevertheless, our model of HD 189733 b, based on the most recently inferred temperature profiles, produces an aerosol distribution that matches the observed transmission spectrum. We argue that the hotter temperature of HD 209458 b inhibits the production of high-altitude aerosols and leads to the appearance of a clearer atmosphere than on HD 189733 b. The aerosol distribution also depends on the particle composition, photochemical production, and atmospheric mixing. Due to degeneracies among these inputs, current data cannot constrain the aerosol properties in detail. Instead, our work highlights the role of different factors in controlling the aerosol distribution that will prove useful in understanding different observations, including those from future missions. For the atmospheric mixing efficiency suggested by general circulation models, we find that the aerosol particles are small (similar to nm) and probably spherical. We further conclude that a composition based on complex hydrocarbons (soots) is the most likely candidate to survive the high temperatures in hot-Jupiter atmospheres. Such particles would have a significant impact on the energy balance of HD 189733 b's atmosphere and should be incorporated in future studies of atmospheric structure. We also evaluate the contribution of external sources to photochemical aerosol formation and find that their spectral signature is not consistent with observations.
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Ciceri, Simona [Verfasser], and Thomas [Akademischer Betreuer] Henning. "Characterizing Transiting Extrasolar Planets / Simona Ciceri ; Betreuer: Thomas Henning." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180610245/34.
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Thrastarson, Heidar Thor. "General circulation modelling of close-in extrasolar giant planets." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2448.
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A large fraction of the extrasolar planets detected so far are giant planets that have such short orbital periods (a few days) that they are thought to be tidally-synchronised with the host star. Such orbits lead to permanent day/night sides on the planets and provide a forcing condition for atmospheric dynamics that is not present in the Solar System. The main subject of this thesis is to model the atmospheric dynamics of these close-in extrasolar giant planets, using an accurate three-dimensional general circulation model (GCM). Using the GCM, the primitive equations are numerically solved, with idealised forcing represented by Newtonian relaxation. A large number of simulations is performed to thoroughly explore the relevant physical and numerical parameter space. First, it is found that different initial flow states lead to markedly different flow and temperature distributions. This result is in contrast with the results or assumptions of many published studies, and underlines the fact that circulation models are currently unsuitable for quantitative predictions without better constrained, and well-posed, initial conditions. Second, the effects of artificial viscosity – particularly in relation to the thermal relaxation timescale – are studied. It is demonstrated that using a large range of thermal time scales, including very short ones ( 1 h), as is common in the literature, leads to dominant noise and/or excessively dissipated fields. Finally, variations of the strength of thermal forcing are studied. Distinct stationary or oscillatory states are identified for different sets of forcing parameters. In addition, multiple long lasting states are observed for a given forcing. Most of the states are characterised by a low number ( 4) of large-scale vortices and planetary waves, which exhibit a periodic time variability. The spatiotemporal variability can be important for observational studies, and provides a strong argument for making repeated measurements of a given planet.
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Burton, John Robert. "Ground-based investigations of the atmospheres of extrasolar planets." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669663.
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In this thesis, I present three main results which demonstrate significant development in the field of exoplanet atmosphere detection and modelling. A model for estimating the distortion of hot-Jupiter exoplanets due to the gravitational attraction by the host star solely based on observable parameters of transiting systems. The most significant case of distortion is that of the exoplanet WASP-12b which shows a bulk density over-estimation of 12%. In order to investigate the systematic sources of error associated with ground-based observations, the secondary eclipse of the transiting hot- Jupiter WASP-19b was observed, and found to have an eclipse depth of O.88±O.19mmag based on a single observation. Whilst this does represent a significant result, the systematics present in the data support further observations to better constrain the depth, duration and timing of the secondary eclipse. The final result presented in this thesis is a pilot study of the technique of 'defocussed transmission spectroscopy', a method of observation which is designed to allow for the detection of elements in the atmospheres of transiting extra-solar planets from groundbased platforms. I present limits on the detectability of sodium in exoplanet atmospheres, and provide a detailed investigation into the systematics associated with this novel observing technique. I also make recommendations as to how future observations can be improved, and present a possible detection of sodium in the atmosphere of WASP-12b with an absorption depth of O.12±O.03%.
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Berton, Alessandro. "Detecting extrasolar planets using IFS-based simultaneous differential imaging." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-70936.
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Barton, Emma Jane. "Hot molecular line lists for extrasolar planets and industry." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1508500/.
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This research is a composite of projects which have individually contributed new results to their respective subjects, whilst collectively contributing to the updating of the ExoMol database to include pressure broadening. This research also represents a successful collaboration between academia and industry. A combination of empirical and ab initio methods were used to compute accurate ro-vibrational line lists for sodium chloride and potassium chloride and refine line lists for carbon monosulphide. Hot line lists for hydrogen chloride, formaldehyde, ammonia and methane were assessed by comparison to high resolution laboratory spectra at temperatures relevant to industrial spectral studies and extrasolar planets. Hot and room temperature Fourier transform infrared spectra of ammonia have been analysed using a variational line list available from ExoMol and, where available, experimental energy levels. Over 5000 new line assignments have been made, providing over 3000 new experimental energies in the range 500 - 11,000 wavenumbers. In addition, an analysis of a room temperature spectrum in the region 9000 - 10,400 wavenumbers has been started. A combined analysis of assigned high resolution experimental spectra of methane available from peer reviewed sources using the MARVEL algorithm has been started. It is intended that the resulting compilation of verified experimental ro-vibrational energies will aid the analysis of hot methane spectra in the region 1000 - 6300 wavenumbers. Custom built pressure and temperature dependent absorption cross sections for water, carbon monoxide, carbon dioxide and ammonia were generated using ExoMol and HITEMP line lists for new spectral retrieval code τ-REx, to facilitate the unbiased analysis of extrasolar planetary spectra. Finally, the data requirements and challenges related to data usage of these separate projects are used to inform the implementation of pressure broadening in the ExoMol database.
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Christiaens, Valentín André. "Imaging of interactions between circumstellar disks and extrasolar planets." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168078.
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Doctor en Ciencias, Mención Astronomía en Cotutela con Universidad de LiejaSe necesitan observaciones para restringir los mecanismos involucrados en el proceso de formación de planetas. Los discos circunestelares ricos en gas y polvo, llamados discos protoplanetarios, son el lugar esperado de nacimiento de los planetas. Esta tesis se aprovecha de la sinergia entre ALMA y los instrumentos de imagen de alto contraste (HCI) para estudiar la formación de planetas y la retroalimentación mutua planeta-disco en discos protoplanetarios con grandes huecos, llamados discos de transición. La primera parte de esta tesis está dedicada a la imagen de estos discos. En particular, se realizó un análisis detallado de las espirales encontradas en MWC 758 y HD 142527. Las espirales de MWC 758 son probablemente debidas a la presencia de dos compañeros, con uno de ellos posiblemente detectado dentro de la cavidad en base a nuestros datos. En el caso de HD 142527, las espirales del borde de la cavidad parecen ser, junto con otras características del disco, productos de la interacción dinámica entre la binaria y el disco. Las espirales frías a mayor escala vistas con ALMA podrían estar relacionadas con la inestabilidad gravitacional del disco o las sombras proyectadas por el disco interno inclinado. Para probar la hipótesis que los huecos grandes en los discos de transición se deben a la presencia de compañeros, se llevó a cabo una encuesta HCI de esos discos utilizando VLT/NACO en IR térmico, presentada en la segunda parte de esta tesis. Se implementaron códigos de reducción de datos que se utilizaron para buscar compañeros en todos los discos ya observados en esta encuesta. Hasta el momento, se han identificado cuatro candidatos compañeros (de 15 fuentes observadas), aunque se requiere seguimiento para confirmar que son verdaderos compañeros. También se presenta mi contribución a la detección de un compañero subestelar joven muy rojo en el disco de escombros de HD 206893. El potencial de los espectrógrafos de campo integral (IFS) para detectar y caracterizar compañeros de baja masa está investigado en la tercera parte de esta tesis. Se observó una muestra de cinco discos de transición usando VLT/SINFONI en infrarojo cercano. La combinación de imagen diferencial angular y espectral (ASDI) permitió suprimir las imperfecciones del halo estelar de manera eficaz y lograr altos contrastes. Se detectaron tres compañeros y dos sistemas con espirales. En particular, se detectó el compañero de baja masa HD 142527 B en la mayoría de los canales espectrales lo que permitió llevar a cabo una caracterización espectral detallada y estimar sus parámetros físicos. En conclusión, esta tesis provee nueva información sobre los discos de transición y el posible vínculo entre los grandes huecos y la presencia de compañeros. Un análisis similar al caso de HD 142527 se aplicará a los compañeros confirmados en nuestras encuestas para entender mejor las interacciones compañero-disco y la formación de planetas.
Este trabajo ha sido parcialmente financiado por CONICYT-PCHA/Doctorado Nacional/2016-21161112
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Bond, Jade. "The Chemistry of Extrasolar Planetary Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194946.
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This work examines the chemical nature of extrasolar planetary systems, considering both the host star and any potential terrestrial planets located within the system. Extrasolar planetary host stars are found to be enriched over non-host stars in several r- and s-process elements. These enrichments, however, are in keeping with general galactic chemical evolution trends. This implies that host stars have not experienced any unusual chemical processing or pollution and that the observed enrichments are primordial in nature.When combined with detailed chemical models, the dynamical models of O'Brien et al. (2006) are found to produce terrestrial planets with bulk elemental abundances in excellent agreement with observed planetary values. This clearly indicates that the combination of dynamical and chemical modeling applied here is successfully reproducing the terrestrial planets of the Solar System to the first order. Furthermore, these planets are found to form with a considerable amount of water, negating the need for large amounts of exogenous delivery. Little dependence on the orbital properties of Jupiter and Saturn is observed for the main rock-forming elements due to the largely homogenous disk composition calculated.The same modeling approach is applied to known extrasolar planetary systems. Terrestrial planets were found to be ubiquitous, forming in all simulations. Generally, small (< 1ML) terrestrial planets are produced close to their host star with little radial mixing occurring. Planetary compositions are found to be diverse, ranging from Earth-like to refractory dominated and C-dominated, containing significant amounts of carbide material. Based on these simulations, stars with Solar elemental ratios are the best place to focus future Earth-like planet searches as these systems are found to produce the most Earthlike terrestrial planets which are located within the habitable zones of their systems and containing a significant amount of water. C-rich planets, although unusual, are expected to exist in >20% of known extrasolar planetary systems based on their host star photospheric compositions. These planets are unlike any body we have previously observed and provide an exciting avenue for future observation and simulation.
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Mustill, Alexander James. "The dynamics of planets and discs." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610345.
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Christiansen, Jessie Leigh Physics Faculty of Science UNSW. "A tale of two surveys: searching for extrasolar planets from Australia and Antarctica." Awarded By:University of New South Wales. Physics, 2007. http://handle.unsw.edu.au/1959.4/43629.
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The transit method of detecting extrasolar planets relies on the small periodic changes in the brightness of the planet's host star as the planet orbits between the observer and the star. Transiting planets are extremely useful discoveries due to the significant gain in information that can be obtained on the planet and its host star than extrasolar planets discovered with other methods. The field of transiting planets has matured rapidly in the last 5 years, particularly in the area of wide-field surveys. This thesis describes the results of two such surveys. The Vulcan South Antarctic Planet Finder was designed to exploit the conditions at the South Pole, which are ideal for a transit survey. Several hardware failures resulted in the acquisition of only a small amount of corrupted data on a single field. The University of New South Wales Extrasolar Planet Search is an ongoing transit survey using the 0.5-m Automated Patrol Telescope at Siding Spring Observatory, Australia. 25 fields were observed for 1-4 months each between 2004 October and 2007 May. Light curves were constructed for ~87,000 stars down to I= 14th magnitude, and from these 23 planet candidates were identified. Ten candidates were eliminated using higher spatial resolution archived images and online catalogue data. Eight were followed up with higher spatial resolution imaging and/or medium resolution spectroscopy and were determined to be eclipsing binaries. Five candidates remain that require additional observation to determine their nature. No planets have been confirmed in this data set thus far. The large sets of high precision light curves generated by transit surveys hold significant potential for additional data-mining. To demonstrate this, a variable star catalogue was compiled from the full data set. A total of 850 variable stars were identified, with 659 new discoveries. In the course of compiling this catalogue, the first example of a high-amplitude δ Scuti star in an eclipsing binary was identified. This represented the first opportunity for a dynamical mass measurement of a highamplitude δ Scuti star, and the system was studied comprehensively.
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Baines, Ellyn. "Inspection and characterization of exoplanet systems using the CHARA Array." unrestricted, 2007. http://etd.gsu.edu/theses/available/etd-08062007-165009/.
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Thesis (Ph. D.)--Georgia State University, 2007.Title from file title page. Harold A. McAlister, committee chair; Todd J. Henry, Douglas R. Gies, Theo A. ten Brummelaar, Nikolaus Dietz, committee members. Electronic text ( 433 p. : ill.) : digital, PDF file. Description based on contents viewed Oct. 29, 2007. Includes bibliographical references (p. 184-194).
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Chan, Ka-ho, and 陳嘉豪. "Numerical exploration of the probability of capture into the 3:1 mean motion resonance." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B4979971X.
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Mean-motion resonances (MMR) are frequently observed in extrasolar planetary systems. It is generally believed that the resonances result from the convergent migration of planets. The much larger number of systems near the 2:1 resonance compared to 3:1 resonance in both the radial velocity and the Kepler data is probably due to the difference in the capture behaviors of 2:1 and 3:1 resonances.
To study the capture probability of the 3:1 resonance, numerical three-body integrations with forced migration have been used to examine the dependence of the capture probability on migration rate, planetary masses, and initial orbital eccentricities. First, the numerical results have been confirmed with analytic theory in the adiabatic limit (Borderies & Goldreich 1984) and numerical results of the Hamiltonian model beyond this limit (Mustill & Wyatt 2011) for both the interior and exterior resonances in the circular restricted three-body problem. Then, the numerical exploration of the restricted three-body problem (R3BP) has been extended to cases with non-zero planet eccentricity in the adiabatic limit. The capture probability decreases with increasing planet eccentricity at small test particle eccentricity but does not depend strongly on the planet eccentricity at large test particle eccentricity. Interestingly, the critical eccentricity of the planet, below which resonance capture is certain, is much larger than the critical eccentricity of test particle which was not expected.
Finally, the numerical exploration has been extended to situations with different planetary mass ratio m1/m2. In the cases where both planets are initially on circular orbits, the critical migration rate for certain capture agrees with that of Quillen (2006) in the R3BP. However, it does not change monotonically with m1/m2 and peaks at m1/m2 = 1. For m1/m2 = 1, the resonance capture is certain when the eccentricities of the inner and outer planets are small and decreases as the eccentricities increase. In contrast, the capture probability is low when the eccentricities are small and the capture probability peaks at certain values of the eccentricities in the non-adiabatic limits. The capture probability as a function of planet eccentricities for mass ratios m1/m2 = 0.5 and 2 in the adiabatic limit has also been studied. The capture probability at m1/m2 = 2 shows similar behaviors with m1/m2 = 1 but the capture behaviors at m1/m2 = 0.5 are significantly different from the capture behaviors at m1/m2 = 1.
This research has explored the probability of resonant capture in several new regimes, including the elliptical restricted three-body problem, comparable mass cases in the adiabatic limit and the equal mass case in the non-adiabatic limits. This work enhances our knowledge in the capture behaviors of 3:1 MMR in different limits and is useful in the future studies of the period ratio distribution in extrasolar planet systems.published_or_final_version
Physics
Master
Master of Philosophy
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Hamacher, Duane Willis Physics Faculty of Science UNSW. "A search for transiting extrasolar planets from the southern hemisphere." Publisher:University of New South Wales. Physics, 2008. http://handle.unsw.edu.au/1959.4/40943.
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To date, more than 300 planets orbiting stars other than our sun have been discovered using a range of observing techniques, with new discoveries occuring monthly. The work in this thesis focused on the detection of exoplanets using the transit method. Planets orbiting close to their host stars have a roughly 10 per cent chance of eclipsing (transiting) the star, with Jupiter?sized planets causing a one per cent dip in the flux of the star over a few hours. A wealth of orbital and physical information on the system can be extracted from these systems, including the planet density which is essential in constraining models of planetary formation. To detect these types of planets requires monitoring tens of thousands of stars over a period of months. To accomplish this, we conduct a wide-field survey using the 0.5-meter Automated Patrol Telescope (APT) at Siding Spring Observatory (SSO) in NSW, Australia. Once candidates were selected from the data?set, selection criteria were applied to separate the likely planet candidates from the false?positives. For this thesis, the methods and instrumentation used in attaining data and selecting planet candidates are discussed, as well as the results and analysis of the planet candidates selected from star fields observed from 2004?2007. Of the 65 planet candidates initially selected from the 25 target fields observed, only two were consistent with a planet transit. These candidates were later determined to be eclipsing binary stars based on follow up observations using the 40-inch telescope, 2.3-m telescope, and the 3.9-m Anglo-Australian Telescope, all located at SSO. Additionally, two planet candidates from the SuperWASP-North consortium were observed on the 40-inch telescope. Both proved to be eclipsing binary stars. While no planets were found, our search methods and results are consistent with successful transit surveys targeting similar fields with stars in a similar magnitude range and using similar methods.
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Fjällmyr, Lennart. "En bibliometrisk kartläggning av det astronomiska/astrofysikaliska forskningsområdet ”extrasolar planets”." Thesis, Högskolan i Borås, Institutionen Biblioteks- och informationsvetenskap / Bibliotekshögskolan, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19862.
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The purpose of this study was to bibliometrically investigate and describe the research area called “extrasolar planets”. The research questions were: Which authors were mostly cited within the area when the first authors (and their co-authors) were considered? Which authors were found in most co-occurrences? Did particular author collaborations emerge?To which institutions were most authors affiliated and did the size of the institution have an influence on whether an author was cited?What was the geographic distribution of authors and institutions and were there any patterns of collaboration?Did the image of dominating institutions and countries depend on the viewpoint?How applicable was Lotka’s law on the collected data? The data was collected from citation lists in documents from the database Arxiv.org. The documents were extracted by using the search term “extrasolar planets”. By using citation analysis and the method a)”first author counting”, complimented by the method b)”fractional counting” used on a material screened by method a), for accrediting publications to authors and countries, an image of the research area was depicted. Method b) was also used for extracting information about author collaboration and geographic distributions. The most quoted first author, also found in most co-occurrences, was attached to the largest institution, located in USA. Most quoted authors, almost 60%, were attached to USA. However, the results were inconclusive when the viewpoints were changed. Apart from the fact that 57.8% of the quoted documents originated from 9.5% of the first authors, Lotka’s law was not applicable.
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Gallardo, José. "Physics of low mass stars, brown dwarfs and extrasolar planets." Lyon, École normale supérieure (sciences), 2007. http://www.theses.fr/2007ENSL0412.
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Alsubai, Khalid. "Wide angle search for extrasolar planets by the transit method." Thesis, St Andrews, 2008. http://hdl.handle.net/10023/521.
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Dittmann, Jason A. "Observing Extrasolar Planets at the University of Arizona's Kuiper Telescope." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146800.
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Morgan, Rhonda Michelle. "Achromatic nulling beam combiner for the detection of extrasolar planets." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279844.
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Nulling stellar interferometry may enable the discovery of earth-like planets around other stars. In nulling mode, the zero order fringe is destructive and on axis, thus canceling light from a bright source and detecting dimer off-axis features. To create deep on-axis nulls, the phase must be shifted half a wave achromatically over a broad band. The phase shift is created by adding optical path thickness with dielectric plates. Plates of different materials can balance dispersion. The nulling solutions found for TPF (infrared) and for SIM (visible) are promising. This dissertation describes the implementation of a nulling beam combiner test bed and presents data characterizing its performance. Although the implementation was limited so that a broad band null of 10E-4 was not attained, the test bed revealed the extreme challenges of this technique and provided very valuable lessons that will enable future implementations to be successful and more precise. The nulling beam combiner testbed was implemented in the laboratory as a Michelson interferometer with the goal of achieving a stabilized, l0E-4 null over a spectral region from 600 nm to 800 nm. The beam combiner system has three tiers of control. Tier 1 controls phase achromaticity by tilting optical plates and is a static control loop. Tier 2 sweeps through the white light fringe and then searches for the null as the air path drifts over minutes. Tier 3 stabilizes the null with a 300 hertz servo loop. A scheme for active control of the optical thicknesses was developed. The phase as a function of wavelength was measured by performing PSI on a spectrally dispersed fringe. The phase was fit to a model to solve for the optical thicknesses. The optical thicknesses were then adjusted to match the ideal thicknesses of an optimized solution. This process of measuring and adjusting the optical thicknesses is performed iteratively to achromatize the phase. The stabilizing servo loop sensed on a grey fringe at a short wavelength. At the shorter wavelength, the fringe was 90 degrees out of phase with the main pass band resulting in a grey fringe. The grey fringe intensity is more sensitive to OPD changes.
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Weldrake, David Thomas Frederick. "Giant planets and variable stars in globular clusters /." View thesis entry in Australian Digital Theses Program, 2005. http://thesis.anu.edu.au/public/adt-ANU20050616.191315/index.html.
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Grether, Daniel Andrew Physics Faculty of Science UNSW. "Statistical analyses of extrasolar planets and other close companions to nearby stars." Awarded by:University of New South Wales. School of Physics, 2006. http://handle.unsw.edu.au/1959.4/29182.
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We analyse the properties of extrasolar planets, other close companions and their hosts. We start by identifying a sample of the detected extrasolar planets that is minimally affected by the selection effects of the Doppler detection method. With a simple analysis we quantify trends in the surface density of this sample in the Msini-period plane. A modest extrapolation of these trends puts Jupiter in the most densely occupied region of this parameter space, thus suggesting that Jupiter is a typical massive planet rather than an outlier. We then examine what fraction of Sun-like (~ FGK) stars have planets. We find that at least ~25% of stars possess planets when we limit our analysis to stars that have been monitored the longest and whose low surface activity allow the most precise radial velocity measurements. The true fraction of stars with planets may be as large as ~100%. We construct a sample of nearby Sun-like stars with close companions (period < 5 years). By using the same sample to extract the relative numbers of stellar, brown dwarf and planetary companions, we verify the existence of a very dry brown dwarf desert and describe it quantitatively. Approximately 16% of Sun-like stars have close companions more massive than Jupiter: 11% +- 3% are stellar, <1% are brown dwarf and 5% +- 2% are giant planets. A comparison with the initial mass function of individual stars and free-floating brown dwarfs, suggests either a different spectrum of gravitational fragmentation in the formation environment or post-formation migratory processes disinclined to leave brown dwarfs in close orbits. Finally we examine the relationship between the frequency of close companions and the metallicity of their Sun-like hosts. We confirm and quantify a ~4 sigma positive correlation between host metallicity and planetary companions. In contrast we find a ~2 sigma anti-correlation between host metallicity and the presence of a stellar companion. Upon dividing our sample into FG and K sub-samples, we find a negligible anti-correlation in the FG sub-sample and a ~3 sigma anti-correlation in the K sub-sample. A kinematic analysis suggests that this anti-correlation is produced by a combination of low-metallicity, high-binarity thick disk stars and higher-metallicity, lower-binarity thin disk stars.
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Voss, Holger. "Developing a ground-based search system for transits of extrasolar planets." [S.l.] : [s.n.], 2006. http://opus.kobv.de/tuberlin/volltexte/2006/1354/index.html.
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Hidas, M??rton Gergely Physics Faculty of Science UNSW. "A search for transiting extrasolar planets with the automated patrol telescope." Awarded by:University of New South Wales. School of Physics, 2005. http://handle.unsw.edu.au/1959.4/22803.
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In the past decade some 150 planets have been detected outside our Solar System, mostly via precise radial-velocity measurements of their host stars. Using an alternative method, transit searches have recently added 6 planets to the tally, and are expected to make more significant contributions in the future. The transit method is based on the detection of the tiny, periodic dip in the apparent brightness of a star when an orbiting planet passes in front of it. It requires intensive photometric monitoring of ??? 104 stars, with a precision better than ??? 1%. The 0.5 m Automated Patrol Telescope (APT) at Siding Spring Observatory, Australia, with its wide field of view and large aperture, is ideal for this task. This combination is also somewhat unique among telescopes used in transit searches. Since 2001, the APT has been semi-dedicated to a search for extrasolar planets. In this thesis work, observing, data reduction and analysis procedures were developed for the project. A significant fraction of the initial effort was focused on reaching the required photometric precision. This was achieved by implementing a new observing technique, and robust data reduction software. In the first two years of regular observations (starting in August 2002), 8 crowded Galactic fields were monitored, with photometric precision reaching 0.2% for the brightest stars. We searched the lightcurves of the brightest stars (V <13) and selected 5 planet candidates. Follow-up photometry and spectroscopy revealed all of these to be eclipsing binary stars. To date, no planets have been detected by this project. A detailed Monte Carlo simulation of the observations, using the currently known frequency and properties of extrasolar planets, resulted in a low calculated detection rate, consistent with the lack of detections. Using this simulation, we have investigated the observational and target star/planet parameters that determine the sensitivity of transit searches. The results highlighted the factors limiting our detection rate, and allowed us to significantly improve our observing strategy. According to the simulations, we should now detect ??? 2 planets per year. This will increase by a factor of a few when a new camera, currently under construction, is installed on the APT in early 2006.
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Kains, Noé. "The Solar System in perspective : from debris discs to extrasolar planets." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1030.
Full textAbstract:
The last twenty-five years have seen our understanding of the formation and abundance of planets revolutionised, thanks to the first detections of debris discs, and, a decade later, of the first extrasolar planets. Hardly a week now goes by without a planet discovery, and the range of methods used to search for planets has expanded to include techniques that are efficient at detecting different types of planets. By combining the discoveries of the various methods, we therefore have the opportunity to build a picture of planet populations across the Galaxy. In this thesis, I am presenting work done as a basis towards such an effort: first I present work carried out to improve modelling methods for gravitational microlensing events. Since the first microlensing observing campaigns, the amount of data of anomalous events has been increasing ever faster, meaning that the time required to model all observed anomalous events is putting a strain on available human and computational resources. I present work to develop a method to fit anomalous microlensing events automatically and show that it is possible to conduct a thorough and unbiased search of the parameter space, illustrating this by analysing an event from the 2007 observing season. I then discuss the possible models found with this method for this event, and their implication (Kains et al. 2009), and find that this algorithm locates good-fit models in regions of parameters that would have been very unlikely to be found using standard modelling methods. Results indicate that it is necessary to use a full Bayesian approach, in order to include prior information on the parameters. I discuss the analytical priors calculated by Cassan et al. (2009) and suggest a possible form of an automatic fitting algorithm by incorporating these priors in the algorithm used by Kains et al. (2009). Another topic with which this thesis is concerned is the evolution of debris discs around solar-type stars. Late-type stars are expected to be the most numerous host stars of planets detected with the microlensing technique. Understanding how their debris discs evolve equates to understanding the earliest stages of planet formation around these stars, allowing us to truly put our Solar System in perspective. Using the analytical model of Wyatt et al. (2007a), I modelled the evolution of infrared excess flux at 24 and 70 microns using published data of debris discs around solar-type (spectral types F, G and K) stars from the Spitzer Space Telescope. By comparing the results of this study to an analogous study carried out by for A stars by Wyatt et al. (2007b), I find that although best-fit parameters are significantly different for solar-type stars, this may be due to the varying number of inefficient emitters around stars of different spectral types. I suggest that although effective properties are different by an order of magnitude or more, intrinsic properties, while still different, are so by a much smaller factor. These differences may be due to the longer timescales over which solar-type stars evolve, which allow for the formation of larger and stronger planetesimals.
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Anderson, David Robert. "The discovery and characterisation of the extrasolar planets of WASP-South." Thesis, Keele University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602973.
Full textAbstract:
SuperWASP is a ground-based survey for transiting extrasolar planets. I present some of my contributions to the project's infrastructure and operations, as well as the discovery and characterisation of seven short-period, giant, transiting extrasolar planets and a 51-Jupiter-mass, transiting brown dwarf. Of particular note is the planet WASP-l7b, which is the largest known planet (Rpl = 1.99 ± 0.08 RJup ) and was the first reported to be in a retrograde orbit. WASP-17b offers one of the most extreme tests of the mechanisms suggested as responsible for the observed bloating of a subset of 'hot Jupiters'. The planet's retrograde orbit indicates that at least some hot Jupiters arrived in their current short orbits via scattering processes rather than via migration by planet-disc tidal interaction. As transiting brown dwarfs are rare, WASP-30b should prove a useful test of models. For the exoplanets WASP-22b and WASP-26b, I present spectroscopic observations of their transits. WASP-22b was found to be in a prograde orbit, but the orientation of the orbit of WASP-26b was not determined with confidence, owing to observation noise and the predicted small amplitude of the signal. I present measurements, via observations of occultations of the planets by their host stars, of the infrared thermal emission of the atmospheres of WASP-19b and WASP-17b. The atmosphere of WASP-19b appears to lack a strong atmospheric temperature inversion and inefficiently transports energy from its day-side to its night-side. For WASP-17b, the data are consistent with a low-albedo atmosphere that efficiently redistributes heat from its day-side to its night-side. For both systems, the occultation timings provide a constraint on orbital eccentricity; this proved especially useful for the WASP-17b system, as it removed the previous large uncertainty on the stellar and planetary radii.
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Barnes, Jason Wayne. "Characterizing transiting extrasolar giant planets: On companions, rings, and love handles." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290019.
Full textAbstract:
For my Ph.D. research I investigated the prospects for characterizing transiting extrasolar giant planets from their transit lightcurves. Hubble Space Telescope photometry of transiting planet HD209458b revealed that the planet has no moons. Here, I show that tidal orbital evolution of moons limits their lifetimes, and hence that no moons larger than Amalthea in size should survive around HD209458b, consistent with observations. I then calculate the detectability and scientific potential of planetary rings and oblateness. Oblateness will prove difficult to reliably detect, even with the Hubble Space Telescope. However, large Saturn-like ring systems should be easy to find around transiting extrasolar giant planets if such rings exist.
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Granata, Valentina. "Numerical algorithms for the searching of extrasolar planets from photometric data." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425016.
Full textAbstract:
The aim of this research project was twofold: on one hand, we have developed an automatic photometric pipeline with a real time images reduction, which directly provide lightcurves of objects observed in the field. The lightcurves themselves are analyzed in order to catch light diming due to a transit.
On the other hand, we contribute to investigate the dynamical and physical structure of the planetary systems hosted in multiple stellar systems and to compare the results with the current knowledge both of the planetary and stellar formation in order to gain a new insight on the evolution of extrasolar systems.
Even if this PhD Thesis is made up of these two different but complementary aspects, however the final aim of both converges: it contributes to the comprehension of the planetary formation mechanism in order to identify both the environment conditions where these objects could form and some clues on their physical properties. Moreover, the results may be applied to the future space missions: the reduction pipeline could be exploited in whatever surveys of transit search thanks to its automatic nature while the theoretical results could be the
starting point for the future investigations from space.
Part I: Photometric reduction and analysis software.
An exoplanetary transit occurs when it crosses the line of sight between the observer and the star around which it is orbiting. The flux decrease that it provokes allows us to find out certain orbital parameters and some physical characteristics of the planet that are inaccessible through other techniques. The diversity of the performed studies and the acquired knowledge after the detection of HD 209458b 's transits motivated the use of this technique as a tool for exoplanet discoveries.
In this thesis, we describe the reduction algorithm developed in the RATS (RAdial velocities and Transit Search) project context in order to automatically achieve the lightcurves of photometric stars devoted to the search for exoplanets using the transit method. The main aim of the RATS project is twofold. The detection of extra solar planets that transit the disk of their parent star is the main scientific drive of the whole project. We have planned to observe simultaneously thousands of stars (magnitude range between 9th to 14th) in selected star fields for five years since the beginning of 2005. In this manner we are confident to find new transiting planets.
The second aim of the project is to use its observing strategy and the scientific data management as a bench work for future planetary transits search mission in order to value it effectiveness.
In particular, RATS projects seeks high precision photometric results performed with stellar images which have been purposely defocused in order to avoid saturation of brighter stars because of the size of Schmidt FoV. Moreover, to maximize the transit probability, each RATS field has been partitioned in seven adjacent sub-fields sequentially pointed.
Up to now, two missions already plan to exploit this untypical strategy: the French CoRoT mission devoted to extrasolar planets search and asteroseismology is planning to collect CCD images which are slightly de-focused; the same observational approach has also been proposed for the Kepler extrasolar space mission as well.
Originally, this research project foresaw many observations from the Cima Ekar Schmidt telescope equipped with a frame transfer CCD lended from INAF-OACT (Istituto Nazionale
di AstroFisica-Osservatorio Astronomico di Catania) in concomitance to the very beginning of RATS project. For reasons out of my hands, some months ago INAF-OACT unexpectedly demand it back and the observations were stopped for a considerable amount of time. This aspect, added to the bad weather conditions of the most of 2006, has lessened images acquisition relative to initial expectations. However, in order to automatically reduce the images obtained so far, we have developed an automatic reduction algorithm RATS{ARP (Automatic Reduction Pipeline) which directly provides light curves of objects in the pre-selected RATS fields. The light curves themselves are analyzed in order to catch light diming due to a planetary transit.
This software is based on different modules all called from a main program shell script, each being deputy to an individual step for photometric reduction of images.
The described procedure has been applied both to the images in focus and to defocused ones, in particular two stellar fields have been analyzed among those chosen for the project.
RATS{ARP has shown its robustness in managing both kind of images, performing all its tasks till lightcurve files creation with satisfactory time consuming: it has taken 90 seconds for each
image in focus and 180 seconds for each defocused frame, depending on the crowding of the field.
Therefore, the pipeline can manage different kind of images and it fulfills all its task. Thereby, we can say that RATS-ARP can be exported to projects different from RATS thanks to its pliability.
In particular, thanks to its automatic development approach, it could be easily applicable to future space missions which intend to search exoplanets with the transit method with small
adjustments.
A detailed analysis for the future implementation of RATS database has been, finally, performed. Requirements and structure of this archive have been identified in order to help in developing a database that can be offered both to scientific community and to non-specialists.
Part II: Dynamical simulations
The present dynamical configuration of planets in binary star systems may not reflect their formation process since the binary orbit may have changed in the past after the planet formation
process was completed. An observed binary system may have been part of a former hierarchical triple that became unstable after the planets completed their growth around the primary star.
Alternatively, in a dense stellar environment even a single stellar encounter between the star pair and a singleton may significantly alter the binary orbit. In both cases the planets we observe at present would have formed when the dynamical environment was different from the presently observed one.
We have numerically integrated the trajectories of the stars (binary plus singleton) and of test planets, hosted around the primary star of the inner binary, to investigate the above mentioned mechanisms. Different values of mutual inclination, binary separation and singleton initial semimajor axis are explored in a statistical way.
Our simulations show that the circumstellar environment during planetary formation around the primary was gravitationally less perturbed when the binary was part of a hierarchical triple
because the binary was necessarily wider and, possibly, less eccentric. We find that a significant mutual inclination between the singleton and the binary is a key factor for instability of the
planetary system in terms of orbital spacing, eccentricity, and mass of the individual planets.
Infact, from our integration we have found that when the mutual inclination is larger than 40, the fraction of planets in the binary surviving the chaotic phase of the triple declines dramatically.
and for an inclination around 90, the percentage of surviving planets is lower than 20% for all binaries with a semimajor axis smaller than 200 AU. The combination of eccentricity and inclination oscillations of the binary companion induced by the secular perturbations of the singleton and the sequence of close encounters preceding the ejection of one star fully destabilize
a planetary system extending beyond 1 AU from the star.
Even in the case of a single stellar encounter the present appearance of a planetary system in a binary may significantly differ from what it had while planet formation was ongoing.
However, while in the case of instability of a triple the trend is always towards a tighter and more eccentric binary system, when a single stellar encounter affects the system the orbit of the binary can become wider and be circularized.
We can conclude that the frequency of planets in binaries with low separation may be strongly reduced by the residence of the pair in the past in a temporary inclined hierarchical triple.
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Street, Rachel. "A search for extra-solar planetary transits in the field of open cluster NGC 6819." Thesis, University of St Andrews, 2002. http://hdl.handle.net/10023/12939.
Full textAbstract:
The technique of searching for extra-solar planetary transits is investigated. This technique, which relies on detecting the brief, shallow eclipses caused by planets passing across the line of sight to the primary star, requires high-precision time-series photometry of large numbers of stars in order to detect these statistically rare events. Observations of ~ 18000 stars in the field including the intermediate-age open cluster NGC 6819 are presented. This target field contrasts with the stellar environment surveyed by the radial velocity technique, which concentrates on the Solar neighbourhood. I present the data-reduction techniques used to obtain high-precision photometry in a semi-automated fashion for tens of thousands of stars at a time, together with an algorithm designed to search the resulting lightcurves for the transit signatures of hot Jupiter type planets. I describe simulations designed to test the detection efficiency of this algorithm and, for comparison, predict the number of transits expected from this data, assuming that hot Jupiter planets similar to HD 209458 are as common in the field of NGC 6819 as they are in the Solar neighbourhood. While no planetary transits have yet been identified, the detection of several very low amplitude eclipses by stellar companions demonstrates the effectiveness of the method. This study also indicates that stellar activity and particularly blending are significant causes of false detections. A useful additional consequence of studying this time-series photometry is the census it provides of some of the variable stars in the field. I report on the discovery of a variety of newly-discovered variables, including Algol-type detached eclipsing binaries which are likely to consist of M-dwarf stars. Further study of these stars is strongly recommended in order to help constrain models of stellar structure at the very low mass end. I conclude with a summary of this work in the context of other efforts being made in this field and recommend promising avenues of further study.
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Biller, Beth Alison. "A High Contrast Survey for Extrasolar Giant Planets with the Simultaneous Differential Imager (SDI)." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194542.
Full textAbstract:
We present the results of a survey of 45 young (<250>Myr), close (<50>pc) stars with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT for the direct detection of extrasolar planets. Our SDI devices use a double Wollaston prism and a quad filter to take images simultaneously at three wavelengths surrounding the 1.62 um methane absorption bandhead found in the spectrum of cool brown dwarfs and extrasolar giant planets. By performing a difference of adaptive optics corrected images in these filters, speckle noise from the primary star can be significantly attenuated, resulting in photon (and flat-field) noise limited data. In our VLT data, we achieved H band contrasts > 10 mag (5 sigma) at a separation of 0.5" from the primary star on 45% of our targets and H band contrasts of > 9 mag at a separation of 0.5'' on 80% of our targets. With this degree of attenuation, we should be able to image (5 sigma detection) a 7 MJup planet 15 AU from a 70 Myr K1 star at 15 pc or a 7.8 MJup planet at 2 AU from a 12 Myr M star at 10 pc. Using the capabilities of the unique SDI device, we also discovered a methane-rich substellar companion to SCR 1845-6357 (a recently discovered (Hambly et al., 2004) M8.5 star just 3.85 pc from the Sun (Henry et al., 2006) at a separation of 4.5 AU (1.170''+-0.003'' on the sky) and fainter by 3.57$\pm$0.057 mag in the 1.575 um SDI filter.We also present high resolution (~0.1''), very high Strehl ratio (0.97+-0.03) mid-infrared (IR) adaptive optics (AO) images of the AGB star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs and appeared slightly extended at all wavelengths. With such high Strehls we can achieve super-resolutions of 0.1'' by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star.SDI on ground based telescopes provides significant speckle attenuations down to star-planet contrasts of ~1-3x10^4. To test the classical SDI technique at contrasts of 10^6-9, we implemented a similar multiwavelength differential imaging scheme for the JPL High Contrast Imaging Testbed.
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Barker, Adrian John. "Tidal interactions between planets and stars." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/240581.
Full textAbstract:
Since the first discovery of an extrasolar planet around a solar-type star, observers have detected over 500 planets outside the solar system. Many of these planets have Jovian masses and orbit their host stars in orbits of only a few days, the so-called 'Hot Jupiters'. At such close proximity to their parent stars, strong tidal interactions between the two bodies are expected to cause significant secular spin-orbit evolution. This thesis tackles two problems regarding the tidal evolution of short-period extrasolar planets. In the first part, we adopt a simple model of the orbit-averaged effects of tidal friction, to study the tidal evolution of planets on inclined orbits. We also analyse the effects of stellar magnetic braking. We then discuss the implications of our results for the importance of Rossiter-Mclaughlin effect observations. In the second part, we study the mechanisms of tidal dissipation in solar-type stars. In particular, internal gravity waves are launched at the interface of the convection and radiation zones of such a star, by the tidal forcing of a short-period planet. The fate of these waves as they approach the centre of the star is studied, primarily using numerical simulations, in both two and three dimensions. We find that the waves undergo instability and break above a critical amplitude. A model for the tidal dissipation that results from this process is presented, and its validity is verified by numerical integrations of the linear tidal response, in an extensive set of stellar models. The dissipation is efficient, and varies by less than an order of magnitude between all solar-type stars, throughout their main-sequence lifetimes, for a given planetary orbit. The implications of this mechanism for the survival of short-period extrasolar planets is discussed, and we propose a possible explanation for the survival of all of the extrasolar planets currently observed in short-period orbits around F, G and K stars. We then perform a stability analysis of a standing internal gravity wave near the centre of a solar-type star, to understand the early stages of the wave breaking process in more detail, and to determine whether the waves are subject to weaker parametric instabilities, below the critical amplitude required for wave breaking. We discuss the relevance of our results to our explanation for the survival of short-period planets presented in the second part of this thesis. Finally, we propose an alternative mechanism of tidal dissipation, involving the gradual radiative damping of the waves. Based on a simple estimate, it appears that this occurs even for low mass planets. However, it is in conflict with current observations since it would threaten the survival of all planets in orbits shorter than 2 days. We discuss some hydrodynamic instabilities and magnetic stresses which may prevent this process.
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Griessmeier, Jean-Mathias. "Aspects of the magnetosphere-stellar wind interaction of close-in extrasolar planets." Phd thesis, Katlenburg-Lindau Copernicus GmbH, 2006. http://www.digibib.tu-bs.de/?docid=00013336.
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