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Baroch, López David. "Analysis of high-precision spectroscopic and photometric data for planet and stellar characterisation". Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/673657.
Pełny tekst źródłaLa detección de la primera estrella binaria hace más de 200 años representó el inicio de un nuevo campo en la astrofísica dedicado al estudio de la evolución y las interacciones de estos sistemas, usando como principal herramienta el análisis del movimiento reflejo causado por el cuerpo orbitante. Solo fue cuestión de tiempo que los instrumentos de medida alcanzaran un nivel de precisión suficientemente elevado como para detectar los movimientos inducidos por planetas sobre sus estrellas. El descubrimiento del primer exoplaneta hace casi tres décadas supuso la creación de un seguido de proyectos dedicados a la búsqueda de nuevos mundos, los cuales están produciendo un montón de datos que se están usando con la finalidad de estudiar diferentes propiedades de las estrellas. El objetivo principal de esta tesis es el estudio y caracterización de exoplanetas, estrellas y sistemas estelares mediante el análisis de datos provenientes de proyectos dedicados a la busca de exoplanetas con instrumentos de alta precisión. Este es el caso de los proyectos CARMENES y TESS, que tienen el objetivo de encontrar planetas usando el método de la velocidad radial y la detección de tráficos planetarios, respectivamente, poniendo un énfasis especial en estrellas tipo M. Primeramente, hemos desarrollado un nuevo método para determinar las propiedades de las manchas estelares y de los movimientos convectivos en estrellas M usando la variabilidad inducida por la actividad estelar. En particular, hemos modelado las velocidades radiales cromáticas y la fotometría de la estrella YZ CMi usando el software de modelado de actividad estelar StarSim. El análisis ha revelado la presencia de una gran mancha polar con una temperatura 200 K inferior a la de la estrella, encontrando también que el movimiento convectivo de la estrella podría tener un movimiento inverso al esperado. A partir de un análisis combinado de velocidades radiales antiguas y de CARMENES, en esta tesis presentamos la detección de un mini Neptuno y una supertierra alrededor de las estrellas M LSPM J2116+0234 y GJ 686, respectivamente, justo fuera del límite interno de las respectivas zonas habitables. Para evitar la determinación sesgada de las características de los planetas, hemos modelado las señales planetarias conjuntamente con las provenientes de la actividad estelar, los cuales hemos modelado con ruido correlacionado. Los parámetros orbitales resultantes de este análisis corresponden a periodos orbitales de 14.45 d y 15.53 d, y masas mínimas de 12.8 y 6.6 masas terrestres para los planetas LSPM J2116+0234b y GJ 686b, respectivamente. El método de velocidades radiales empleado para detectar exoplanetas con CARMENES también permite la detección de sistemas múltiples. En este trabajo, anunciamos el descubrimiento de 17 nuevos sistemas, de los cuales determinamos las órbitas espectrales. La muestra está formada por 15 sistemas binarios (5 con compañeras no detectadas) y 3 sistemas triples. Hemos determinado que las compañeras no detectadas de dos de las binarias tienen masas mínimas compatibles con una enana marrón, y demostramos que un sistema binario está formado por una enana blanca y una estrella M. Un análisis conjunto de velocidades radiales y astrometría nos ha permitido determinar las masas de un sistema binario, el cual es uno de los sistemas más jóvenes con masas medidas. Por último, hemos usado fotometría de TESS para determinar el tiempo de eclipse de 16 binarias eclipsantes excéntricas. Mediante el análisis de la evolución de las diferencias entre el tiempo de eclipse primario y secundario con el tiempo, hemos determinado el movimiento apsidal de 10 sistemas, 5 de los cuales son medidos por primera vez. Hemos comparado nuestras medidas con predicciones teóricas obteniendo una concordancia excelente. Hemos sido capaces de medir el término relativista con suficiente precisión para testar la relatividad general con este método por primera vez.
The detection of the first binary star more than 200 years ago opened the door to a whole new field of astrophysics research, devoted to the study of their evolution and mutual interactions employing the analysis of the reflex motion caused by the orbiting companion. It was therefore only a matter of time that the development of astronomical instrumentation reached a precise enough level to detect the motions induced by planetary companions over their host stars. The discovery of the first exoplanet a few decades ago prompted a rapid surge of surveys dedicated to their search, which are providing a huge amount of data that can be also used to study the properties of stars. The main purpose of this thesis is the study and characterization of exoplanets, stars, and stellar systems by analyzing data from high-precision spectroscopic and photometric exoplanet surveys. This is for instance the case of the CARMENES and TESS projects, which aim at the discovery of such objects by means of the radial velocity imprinted on their host star or by the detection of transits, respectively, with particular emphasis on low-mass M-dwarf stars. Firstly, we developed a novel approach to constraint the properties of starspots and convective motions on M dwarfs by using the variability induced by stellar activity. In particular, we modeled chromatic radial velocities and photometric time series of the M-dwarf star YZ CMi using the stellar activity model code StarSim. The results of our analysis revealed the presence of a large polar spot with a temperature 200 K lower than that of the surrounding photosphere, and found that the convective shift of this star may be reversed toward redshift. Based on a combined analysis of CARMENES and archival radial velocities, we present in this thesis the detection of a mini-Neptune and a super-Earth around the M-dwarf stars LSPM J2116+0234 and GJ 686, respectively, just outside the inner edge of their habitable zones. To avoid determining biased parameters due to the contamination from stellar activity, the planetary signals were jointly modeled with a correlated noise model describing stellar variability. The derived orbital parameters resulted in orbital periods of 14.45 d and 15.53 d, and minimum masses of 12.8 and 6.6 Earth masses for LSPM J2116+0234b and GJ 686b, respectively. The radial velocity method used to detect exoplanets with CARMENES is also yielding multiple stellar systems as a by-product. In this work, we report on the discovery of 17 new multiple systems, for which we determined their spectroscopic orbits. The sample is composed of 15 binary systems (5 with undetected companions) and 2 triple systems. We determined that the unseen companions of two of the binaries have minimum masses compatible with a brown dwarf, and we demonstrated that one of the systems is an M-dwarf--white dwarf binary. We also found one of the youngest binary systems with measured masses by analysing both radial velocities and astrometric measurements. Finally, we used TESS photometry to derive eclipse timings for 16 well-studied eccentric eclipsing binaries. We analyzed the change in the difference between primary and secondary eclipse timings over time to determine the apsidal motion rate of 10 of the systems in the sample, 5 of which are measured for the first time. We compared the measured values with theoretical predictions, obtaining an excellent agreement. We were able to measure the general relativistic.
Universitat Autònoma de Barcelona. Programa de Doctorat en Física
Lafarga, Magro Marina. "Stellar activity and exoplanets ofMdwarfs from CARMENES visible to near-infrared spectroscopy". Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671618.
Pełny tekst źródłaDespués del descubrimiento de los primeros exoplanetas hace unas tres décadas, la detección y caracterización de compañeros planetarios se ha convertido en un tema de investigación prominente, especialmente la búsqueda de planetas parecidos a la Tierra, cuerpos rocosos que orbitan en la zona habitable (HZ) de sus estrellas huéspedes. Uno de los principales métodos utilizados para encontrar y caracterizar exoplanetas es la técnica de la espectroscopía Doppler o velocidad radial (RV), basada en el uso de espectros estelares para medir cambios periódicos en la RV de una estrella causados por la atracción gravitatoria de un exoplaneta en órbita. Actualmente, la variabilidad intrínseca de las estrellas huéspedes es el principal reto en el estudio de exoplanetas. Las estrellas no son cuerpos invariables ni homogéneos, sino que presentan variabilidad en distintas escalas de tiempo. La más relevante es la actividad magnética estelar, que incluye fenómenos como manchas o fáculas que aparecen en la superficie de la estrella y están moduladas por su rotación. Estos fenómenos distorsionan los espectros estelares, introduciendo sesgos en las RVs suficientemente grandes como para esconder o hasta imitar la señal causada por un planeta. Por lo tanto, para continuar detectando y estudiando exoplanetas de baja masa, una mejor comprensión de estos fenómenos estelares y sus efectos en nuestras observaciones es clave. Esta tesis se centra en el estudio de los efectos de la actividad estelar en observaciones espectroscópicas de estrellas frías obtenidas con el instrumento CARMENES. CARMENES es un espectrógrafo de alta resolución capaz de observar en el rango de longitudes de onda visible e infrarojo cercano. Está realizando un estudio de más de 300 enanas M, las estrellas con menor masa de la secuencia principal, con el objetivo primordial de detectar exoplanetas pequeños. En primer lugar, hemos desarrollado un código que implementa el método de la función de correlación cruzada (CCF) para medir RVs e indicadores de actividad estelar en observaciones de alta resolución, y lo hemos aplicado a los datos de CARMENES. Este método usa máscaras binarias ponderadas, un template estelar simplificado construido seleccionando líneas espectrales. Hemos creado varias máscaras en función del subtipo espectral y de la velocidad de rotación de la estrella a analizar. A continuación, hemos utilizado los indicadores de actividad derivados de la CCF, juntamente con otros indicadores de actividad espectroscópicos, para analizar sus variaciones temporales en una muestra de casi 100 enanas M de varias masas y niveles de actividad. Aproximadamente la mitad de las estrellas analizadas muestran RVs con señales de actividad claros. Distintos indicadores son sensibles a la actividad de forma diferente según las características de la estrella: indicadores cromosféricos son más útiles para estrellas de baja actividad, indicadores relacionados con el cambio de RV con la longitud de onda funcionan mejor para estrellas más activas, y otros indicadores relacionados con el cambio de anchura de las líneas fotosféricas proporcionan resultados similares en todo tipo de estrellas, pero son especialmente útiles para las más activas y de menor masa. Finalmente, hemos analizado los efectos de la actividad sobre líneas de absorción individuales presentes en el espectro de estrellas activas. Estudiando las correlaciones entre las RVs de líneas individuales y los indicadores de actividad, podemos clasificar las líneas observadas según su sensibilidad a la actividad. Esto nos permite seleccionar líneas afectadas de forma distinta por la actividad y usarlas para volver a calcular RVs. De esta forma obtenemos RVs para las cuales mitigamos o incrementamos la señal de actividad en diversos grados. También observamos que las mismas líneas en distintas estrellas muestran diferente sensibilidad a la actividad.
After the discovery of the first exoplanets about three decades ago, the detection and characterization of planetary companions has become a prominent research topic, especially the search for Earth-like planets, rocky bodies orbiting in the habitable zone (HZ) of their host stars. One of the main methods used to find and characterise exoplanets is the Doppler spectroscopy or radial velocity (RV) technique, based on using stellar spectra to measure periodic changes in the RV of a star caused by the gravitational pull of an orbiting exoplanet. Currently, the intrinsic variability of the host stars is the major challenge faced in the study of exoplanets. Stars are not quiet, homogeneous bodies, but display variability on different timescales, the most concerning being stellar magnetic activity, phenomena such as spots or faculae appearing on the stellar surface and modulated by the stellar rotation. These features distort the stellar spectra, introducing biases in our RVs that can be large enough to hide or even mimic the signal caused by a planet. Therefore, to continue detecting and studying low-mass exoplanets, a better understanding of these stellar phenomena and their effects on our observations is key. This thesis is focused on the study of stellar activity effects on spectroscopic observations of cool stars obtained with the CARMENES instrument. CARMENES is a high-resolution spectrograph capable of observing on the visible and near-infrared wavelength ranges. It is performing a survey of over 300 M dwarfs, stars at the low-mass end of the main sequence, with the main goal of detecting small exoplanets. Firstly, we developed a pipeline that implements the cross-correlation function (CCF) method to measure RVs and indicators of stellar activity on high-resolution observations, and applied it to the CARMENES survey data. This method uses weighted binary masks, a simplified stellar template built by selecting sharp spectral lines, of which we created different kinds depending on the spectral subtype and the rotational velocity of the target star. We then used the activity indicators derived from the CCF, together with other spectroscopic activity proxies, to analyse their temporal variations in a sample of almost 100 M dwarfs with a range of masses and activity levels. We found that about half of the stars analysed show RVs with clear signals of activity. Different indicators trace activity differently depending on the characteristics of the star: chromospheric indicators are the most useful for low-activity stars, indicators related to the change in RV with wavelength work better for the most active stars, and other indicators related to the change in width of the photospheric lines provide similar results in all types of stars, but are especially useful for the most active and lowest-mass ones. Finally, we analysed the effects of activity on individual absorption features present on the spectra of active stars. By studying the correlations between the individual line RVs and activity indicators, we are able to classify the observed lines according to their sensitivity to activity. This allow us to select differently affected lines and use them to recompute RVs for which we mitigate or enhance the activity signal to varying degrees. We also observe that the same lines on different stars show different sensitivities to activity.
Bochinski, Jakub Jaroslaw. "Observations of transiting exoplanets". Thesis, Open University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.699818.
Pełny tekst źródłaFrith, James Michael. "Towards atmospheric characterisation of exoplanets". Thesis, University of Hertfordshire, 2014. http://hdl.handle.net/2299/14247.
Pełny tekst źródłaSvensson, Rebecka. "Exploring the Diversity of Exoplanets". Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-87402.
Pełny tekst źródłaBrothwell, Rayn David. "The dynamic nature of exoplanets". Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705899.
Pełny tekst źródłaPearson, Kyle A., Leon Palafox i Caitlin A. Griffith. "Searching for exoplanets using artificial intelligence". OXFORD UNIV PRESS, 2018. http://hdl.handle.net/10150/627143.
Pełny tekst źródłaHodosán, Gabriella. "Lightning on exoplanets and brown dwarfs". Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/12079.
Pełny tekst źródłaGeorgieva, Iskra. "Searching for Exoplanets in K2 Data". Thesis, Luleå tekniska universitet, Rymdteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70960.
Pełny tekst źródłaArmstrong, David John. "On the abundance of circumbinary exoplanets". Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/72676/.
Pełny tekst źródłaWaldén, Pierre, i Erik Aronson. "Spectroscopic characterization of transiting exoplanets : A study of the possibility to detect atmospheres around exoplanets using SIMPLE". Thesis, Uppsala universitet, Observationell astrofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-149020.
Pełny tekst źródłaIvanova, Anastasiia. "Contributions to the study of exoplanets : improvement of the stars radial velocity measurements, transit spectroscopy modeling". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASP147.
Pełny tekst źródłaThe radial velocity method was the first method to detect an exoplanet. Since 1995 it has discovered more than 2000 more exoplanets and, although the transit photometry method is currently the most productive, the radial velocity method has its advantages. In addition to being able to discover new exoplanets and determine their apparent mass msini it is used to confirm exoplanets found by other methods and measure the mass of transit exoplanets. However, the RV method is limited by technical capabilities: the size and availability of the telescope, the stability and accuracy of the wavelength calibration of the spectrograph. New generation spectrographs are extremely accurate from an instrumental point of view, they are stable and perfectly calibrated, but their accuracy is still not enough to detect Earth's exoplanet twin. If it is not possible to improve the instrument the data processing needs to be refined, so any improvement of the processing associated to the radial velocity retrieval should result in an improvement of precision, or in a shorter telescope time required to achieve a defined-goal precision.Because the spectra for the radial velocity method are obtained from the Earth's surface, they contain the spectrum of the star and the spectrum of the Earth's atmosphere (telluric absorption). Until recently, spectral regions contaminated by telluric absorption were excluded from consideration. After telluric correction, those regions become available to be used for RV retrieval, improving the precision on RV.This thesis is devoted to the development of telluric correction algorithm (based on TAPAS web service), describing the telluric correction method and estimating an increase in the precision of radial velocity measurements due to increased available wavelength range. The correction method was developed for telluric absorption caused by O2 and H2O in the visible wavelength range and probed on ESPRESSO open data. For our case study of star HD40307, the formal error on RV is reduced from 0.77 to 0.64 ms-1, corresponding to a significant saving of 45% telescope time.In addition to work on the telluric absorption correction, the thesis also focuses on the direct calculation of the radial velocity. At the moment, there are 2 main methods that exist and are widely used: the cross-correlation function (CCF) method and the template matching method. There is also the Pierre Connes method (described at Absolute Astronomical Accelerometry), which has its limitations due to its inability to be applied to large velocity variations. In this thesis we propose and show the application of a new method, which is a combination of the classical method of cross-correlation function and the method of Pierre Connes (PC). We propose to use the PC method of calculating the change of radial velocity directly on the CCF, with prior correction for BERV, instead of the classical Gaussian fitting of the CCF.The method has been tested for data of a star with a planetary system as well as without a planetary system, the results show that the precision of the radial velocity calculation using the PC method is higher than that of the Gaussian fit. The thesis also shows the beginnings of a stellar activity correction, based on the PC method. As the CCF can be considered an averaged stellar line, counting the change in radial velocity for the left and right wings separately, stellar activity can be analysed.The second part of the thesis is dedicated to the development of a transmission spectroscopy model for telluric exoplanets at the beginning of formation. The development of such a model is particularly relevant after the JWST launch and in anticipation of the Ariel launch, as most current models focus more on gas giants and brown dwarfs. A high-resolution line-by-line model has been developed for an atmosphere consisting of H2O vapour and CO2
Dragomir, Diana. "Transiting super-Earth exoplanets : search and characterisation". Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43616.
Pełny tekst źródłaDragomir, Diana. "Characterising the orbits of long period exoplanets". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21929.
Pełny tekst źródłaÀ date presque 300 exoplanètes ont été découvertes, la plupart à travers des mesures du vacillement provoqué par la planète dans le mouvement de son étoile mère. Nous avons mis au point un programme, basé sur l'inférence bayésienne, pour modéliser des données de vélocité radiale pour la recherche d'exoplanètes par des orbites excentriques képlériennes. Les données sont des spectres optiques et ont été recueillies avec le spectromètre échelle HIRES au télescope Keck I. Nous avons utilisé le programme pour analyser 58 ensembles de données. Nous avons obtenu des distributions de probabilité pour la période orbitale ainsi que pour l'excentricité pour chaque ensemble. Nous avons trouvé qu'il est possible de placer des limites supérieures et inférieures sur la période, mais que l'excentricité est plus difficile à contraindre. À partir de la moyenne des distributions de probabilité que nous avons obtenu pour la période, nous avons préliminairement conclu qu'il y a une beaucoup plus grande probabilité de trouver des exoplanètes avec des périodes inférieures à 10000 jours qu'avec des périodes supérieures à 10000 jours. Nous suspectons la présence d'une corrélation entre la période et l'excentricité, ainsi qu'une possible tendance de la période à décroître à mesure que la métallicité stellaire augmente.
Simpson, E. K. "The discovery and characterisation of transiting exoplanets". Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546439.
Pełny tekst źródłaZeng, Li. "Interior Structure and Chemistry of Solid Exoplanets". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467291.
Pełny tekst źródłaAstronomy
Osborn, Hugh P. "Long-period exoplanets from photometric transit surveys". Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/98252/.
Pełny tekst źródłaSamuel, Benjamin. "Détection et caractérisation d’exoplanètes avec le télescope spatial CoRoT : contributions à la découverte et étude physique de la super-terre CoRoT-7b". Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112049/document.
Pełny tekst źródłaThe transit photometry makes it possible to detect exoplanets by measuring their radii. Pursuing this goal, the space telescope CoRoT (Convection, Rotation and planetary Transits), launched in December 2006, is equiped with a high-precision photometer allowing both planet detection by transit photometry, and stellar physics studies (asteroseismology).For this PhD thesis, I have developed various computing tools for the detection and detailed analysis of the transits in CoRoT light curves. I have applied these tools to almost 12 000 stars observed during each of the first ten campaigns of observation. The collaboration between the detection and ground based follow-up teams led to the discovery, up to now, of fifteen planets and two brown dwarfs.It is possible to constrain the physical natures of these exoplanets thanks to the knowledge of the masses and radii: they can be gazeous, icy, rocky or with an mixed nature.The search for rocky planets in particular, is a goal motivated by their singular nature, and both by the paucity of detections of these objects (due to their low masses and radii), Thus, the discovery of CoRoT-7b -- the first exoplanet compatible with a rocky model and whith measured radius (1.6 Earth radius) and mass (around 7 Earth masses) -- allowed us to develope a physical model to which I contributed :I studied the possibility of observing this very hot planet in the near infrared range with JWST, during its orbit, to estimate the temperature contrast between the day and the night faces. This should allow to confirm / invalidate our model with atmosphere dense enough to redistribute heat at the surface of CoRoT-7b
Benneke, Björn. "Bayesian atmospheric retrieval for exoplanets : uniqueness of exoplanet spectra, characterizations of super-earths, and evaluations of dedicated space telescope designs". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82496.
Pełny tekst źródłaThis thesis was scanned as part of an electronic thesis pilot project.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 181-187).
After centuries of studying the eight planets in our solar system, recent improvements in technology have given us the unprecedented opportunity to detect planets orbiting stars other than the sun, so-called exoplanets. Recent statistical studies based on 800 confirmed planets and more than 3000 planet candidates suggest that our galaxy is teeming with billions of planets. Many of them are likely to orbit their host stars at a distance where liquid water and potentially life can exist. Spectroscopic observations of exoplanets can provide us with information about the atmospheres and conditions on these distant worlds. This thesis presents a Bayesian retrieval framework to analyze spectroscopic observations of exoplanets to infer the planet's atmospheric compositions, the surface pressures, and the presences of clouds or hazes. I identify what can unambiguously be determined about the atmospheres of exoplanets by applying the retrieval method to sets of synthetic observations. The main finding is that a unique constraint of the atmospheric mixing ratios of all infrared absorbing gases and up to two spectrally inactive gases is possible if the spectral coverage of the observations is sufficient to (1) determine the broadband transit depths in at least one absorption feature for each absorbing gas and (2) measure the slope and strength of the molecular Rayleigh scattering signature. For the newly discovered class of low-density super-Earths, with radii and masses intermediate between Earth and Neptune, I present an observational approach to distinguish whether these planets more closely resemble the giant planets in our solar system or whether they represent a completely new, potentially water vapor-rich type of planet. The approach discussed in this work represents the science case for the largest Hubble Space Telescope program ever awarded for a single exoplanet. The numerical methods and the conceptual understanding of atmospheric spectra presented in this thesis are key for the design of future space telescopes dedicated to the characterization of transiting exoplanets. I present an integrated design evaluation framework for the proposed Exoplanet Characterization Observatory (EChO) that simultaneously models the astrophysical signal and the telescope's payload module. I demonstrate that costly cryogenic cooling to observe the mid-infrared spectrum beyond ~ 11 [mu]m is not required while visible light observations down to - 400 nm are essential for the mission success. The observational study of exoplanet atmospheres is in its infancy and its pace is poised to accelerate as observational techniques are improved and dedicated space missions are designed. The methods developed in this thesis will contribute to constraining the atmospheric properties of a wide variety of planets ranging from blazingly-hot gas giants to temperate Earth-like planets.
by Björn Benneke.
Ph.D.
Bernardes, Luander. "Exoplanetas, Extremófilos e Habitabilidade". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14131/tde-21062013-162408/.
Pełny tekst źródłaThe main objective of this study is to estimate the chance of survival of microorganisms (extremophiles) on the surface of known exoplanets, as well as on the surface of its potential natural satellites. We used a model that simulates the primordial atmosphere composed by, primarily, nitrogen, water and carbon dioxide. And when it comes to extremophiles, these calculations were not limited to the Habitable Zone of planetary systems, since this concept was extended to a wider region, the Extremophile Zone, where life can exist. Extremophiles are terrestrial microorganisms living under extreme conditions of temperature, light level, humidity, pressure, salinity, pH, etc ... They are natural candidates for living in habitats considered extraterrestrials where such conditions are encountered eventually. Examples of such environments in our solar system are: Mars, Titan (moon of Saturn) and Europe (satellite of Jupiter). There are hundreds of planets orbiting other stars (exoplanets) and most of them are gas giants, particularly Hot Jupiters. The surface temperature of a planet/moon depends heavily on its albedo, its orbital distance, of geodynamic conditions intrinsic, in addition to the spectral type of their host star. The estimate of this temperature was obtained considering the carbon-silicate cycle and a global energy balance, which contributed to obtain estimates of the partial pressure due to atmospheric CO2 and the average temperature on the surface of planets and/or their hypothetical satellites. Natural satellites of giant planets may harbor life, and this possibility was tested by analyzing the conditions of orbital stability of these heavenly bodies. The results of this study should provide support for the hypothesis of panspermia.
Reidarman, Karin. "Exoplanets: Interactive Visualization of Data and Discovery Method". Thesis, Linköpings universitet, Medie- och Informationsteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-156717.
Pełny tekst źródłaGünther, Maximilian Norbert. "Identifying exoplanets and unmasking false positives with NGTS". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277873.
Pełny tekst źródłaBusuttil, Richard. "Investigating exoplanets and transients using small-aperture telescopes". Thesis, Open University, 2017. http://oro.open.ac.uk/49860/.
Pełny tekst źródłaNascimbeni, Valerio. "New techniques to detect and characterize transiting exoplanets". Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422547.
Pełny tekst źródłaLo studio dei pianeti extrasolari (o "esopianeti") è una branca della ricerca astronomica molto giovane e in rapidissima evoluzione. Il lavoro svolto nella presente tesi riguarda principalmente lo sviluppo di nuove tecniche di osservazione e di riduzione e analisi dati al fine di 1) caratterizzare pianeti extrasolari transitanti già noti attraverso fotometria differenziale di alta precisione, condotta da terra; e 2) fare uso degli stessi dati per cercare nuovi corpi in sistemi planetari già noti, sfruttando una tecnica di analisi nota come TTV (Transit Time Variation: variazione dei tempi di transito). Per entrambi gli scopi, ho sviluppato strumenti software indipendenti e mirati al fine di minimizzare o correggere ogni sorgente rilevante di errori sistematici (noto anche come "correlated noise" o "red noise"). Gran parte della mia tesi è focalizzata sulla progettazione e implementazione del progetto TASTE, una campagna osservativa multisito e a lungo termine per monitorare un campione selezionato di esopianeti con telescopi terrestri di classe piccola e media. Il contenuto di ciascun capitolo è riassunto in seguito. 1) Introduzione. In questo capitolo tratterò in breve la situazione attuale della ricerca sugli esopianeti, comprendente anche una panoramica sulle principali tecniche finora impiegate per rivelare e caratterizzare pianeti extrasolari. Quindi passerò a discutere perché e come la comunità scientifica si sta orientando verso la ricerca di pianeti sempre più piccoli e leggeri attorno a stelle brillanti, e illustrerò le tecniche sviluppate per aggirare i limiti attualmente imposti dagli strumenti. In particolare, descriverò in cosa consiste la tecnica TTV, quali sono i principi teorici sui quali si fonda e come questi possano essere applicati a misure reali. Passerò infine in rassegna i primi risultati ottenuti applicando questo metodo, sia da strumentazioni terrestri che dalle missioni spaziali Kepler e CoRoT. 2) Implementazione del progetto TASTE. In questo capitolo descriverò la progettazione e l'implementazione di TASTE nella configurazione originaria: ovvero, come un progetto concepito per un singolo telescopio (il riflettore Copernico da 1.82m presso l'Osservatorio Astrofisico di Asiago). Discuterò i requisiti tecnici imposti, i criteri adottati per la selezione del campione di oggetti, la strategia osservativa e la prima versione della pipeline software STARSKY, ottimizzata per eseguire fotometria differenziale di apertura su immagini appositamente sfuocate. Presenterò le prime curve di luce pubblicate da TASTE, dei pianeti cosiddetti "hot Jupiters" HAT-P-3b e HAT-P-14b, e dimostrerò che esse raggiungono l'accuratezza fotometrica necessaria per rilevare con la tecnica TTV pianeti perturbatori di massa terrestre, nel caso questi ultimi siano bloccati in una risonanza orbitale di basso ordine, come 3:2 o 2:1. Questo capitolo è basato sull'articolo: V. Nascimbeni, G. Piotto, L. R. Bedin, M. Damasso (2011): TASTE: The Asiago Search for Transit timing variations of Exoplanets. I. Overview and improved parameters for HAT-P-3b and HAT-P-14b, A&A, 527, A85. 3) Un nuovo studio osservativo di HAT-P-13b. In questo capitolo presenterò il primo studio TTV osservativo pubblicato dalla collaborazione TASTE. Questo lavoro è stato stimolato da un articolo di Pal et al. (2011) che rivendicava la scoperta di un considerevole segnale TTV nei transiti del pianeta HAT-P-13b (un caso interessante di "hot Jupiter" ospitato da un sistema planetario multiplo). Mostrerò che i dati raccolti da TASTE sono in accordo con le misure di Pal et al. (2011), il che conforta --assieme ad altri dati di archivio-- la possibile presenza di un segnale TTV periodico. Infine metterò in evidenza che lavori più recenti (Southworth et al. 2012, Fulton et al. 2012) hanno tentato di dimostrare che molte misure condotte in passato sono state pubblicate con errori di gran lunga sottostimati, a causa della presenza di red noise trascurato durante la fase di analisi di dati. Per questo motivo, oggi si ritiene probabile che la rivendicazione di Pal et al. (2011) sia spuria. Questo capitolo è basato sull'articolo: V. Nascimbeni, G. Piotto, L. R. Bedin, M. Damasso, L. Malavolta, L. Borsato (2011) TASTE II. A new observational study of transit time variations in HAT-P-13b, A&A, 532, A24. 4) Un'analisi omogenea del sistema WASP-3. In questo capitolo presenterò il primo lavoro del progetto TASTE basato su osservazioni condotte presso l'Observatorio del Teide dell'Instituto de Astrofisica de Canarias (IAC): sei curve di luce ad alta precisione ottenute con il telescopio IAC-80. Descriverò l'analisi approfondita che è stata svolta sia su dati di archivio che sulle nostre misure, facendo uso di tecniche e software di riduzione/analisi omogenei. Lo scopo è di derivare parametri del pianeta e misure di tempo di transito in modo completamente autoconsistente. Illustrerò come l'insieme dei dati disponibili non sia in accordo con il presunto segnale TTV periodico rivendicato da Maciejewski et al. (2010). Al contrario, dimostrerò che la dispersione delle misure TTV è statisticamente significativa, sebbene priva di qualsiasi tipo di periodicità rivelabile. Passerò quindi a discutere le possibili cause di questo comportamento, presentando un'effemeride aggiornata per WASP-3b e ricavando per lo stesso parametri fisici e orbitali aggiornati. Questo capitolo è basato sull'articolo: V. Nascimbeni, A. Cunial, S. Murabito, P. V. Sada, A. Aparicio, G. Piotto, L. R. Bedin, A. P. Milone, A. Rosenberg, L. Borsato, M. Damasso, V. Granata, and L. Malavolta (2012) TASTE III. A homogeneous study of transit time variations in WASP-3b, A&A, submitted. 5) Parametri fisici e orbitali di WASP-1b e HAT-P-20b. In questo capitolo analizzerò quattro curve di luce di alta precisione ottenute serendipicamente con il telescopio da 1.82m di Asiago (un transito di WASP-1b e tre transiti completi di HAT-P-20b). Rianalizzando anche i più accurati dati di archivio attualmente disponibili, derivererò un'effemeride e dei parametri fisici e orbitali più precisi per entrambi i pianeti. Nessuno dei due mostra un segnale TTV significativo. Discuterò infine quali limiti superiori possono essere stimati riguardo alla massa di un ipotetico pianeta perturbatore in base a questa misura nulla. Questo capitolo è basato sull'articolo: V. Granata, V. Nascimbeni, G. Piotto, L. R. Bedin, L. Borsato, M. Damasso, L. Malavolta (2012) TASTE IV. Refined ephemeris and parameters for WASP-1b and HAT-P-20b, A&A, in preparation. 6) Una ricerca di pianeti in NGC 6397 In questo capitolo descriverò una ricerca di pianeti transitanti e stelle variabili condotta in un campo stellare periferico dell'ammasso globulare NGC 6397, sfruttando osservazioni di archivio del telescopio spaziale Hubble. Il campione principale è costituito da un insieme di ~2200 nane rosse appartenenti all'ammasso. Descriverò gli algoritmi che ho sviluppato per correggere gli errori fotometrici sistematici presenti in un insieme di 252 immagini ultraprofonde riprese con la camera ACS nel 2006. Poiché non sono stati rivelati transiti, discuterò la significatività di questo risultato nullo. Infine, descriverò e caratterizzerò dodici stelle variabili di diverse tipologie scoperte per la prima volta. Tutte queste variabili sono sorgenti di campo, non appartenenti all'ammasso. Questo capitolo è basato sull'articolo: V. Nascimbeni, L. R. Bedin, G. Piotto, F. De Marchi, R. M. Rich (2012) An HST search for planets in the lower Main Sequence of the globular cluster NGC 6397, A&A, 541, A144. 7) Selezione del campo di vista di PLATO Nell'ultimo capitolo passerò in rassegna il lavoro che mi ha visto coinvolto nello studio preparatorio per PLATO. PLATO è una missione spaziale proposta all'ESA che cercherà principalmente pianeti "abitabili" di piccola massa attorno a stelle brillanti, coprendo alla fine della missione un angolo sferico pari al ~40% dell'intero cielo. I target adatti comprendono stelle nane e subgiganti di tipo spettrale F5V e più freddi, più brillanti della magnitudine V~13. Tali target devono essere selezionati prima dell'inizio della missione vera e propria, pertanto è necessaria una classificazione stellare su tutto il cielo, e molto più profonda di quelle attualmente disponibili. All'interno del gruppo di lavoro WP 131210 ("Analysis of photometric and astrometric catalogues") ho investigato la fattibilità e l'affidabilità delle tecniche di classificazione stellare basate sui cataloghi fotometrici e astrometrici, sia quelli disponibili che quelli di prossima realizzazione.
Bachelet, Étienne. "Détection d'exoplanètes par effet de microlentille gravitationnelle : des observations à la caractérisation". Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2138/.
Pełny tekst źródłaThe search of exoplanets using gravitational microlensing started in 1995. First results come quickly and the first exoplanet has been detected on 2003 by the OGLE and the MOA collaborations. Nowadays, more than twenty exoplanets are published and the number of detections should rise a lot in the coming years with the launch of KMTNet survey and EUCLID and WFIRST space-based observatories. When a "close" star, the lens, cross the line of sight between the Earth and a more distant star, the source, the luminosity of this source is magnified. By chance, if a planet orbits this lens star, it produces a second magnification of lower amplitude. The lightcurve of the event then shows a typical signature : a planetary deviation. In this manuscript, we present the theoritical and observational tools needed to detect planets with gravitational microlensing. We present two studies on two special events : MOA-2009-BLG-411L, a lens formed by a brown dwarf around an M-dwarf, and MOA-2010-BLG-477Lb, a super-Jupiter orbiting an M star. We finally present a study on planets already published in order to standardize theses results. Two major problems make this research difficult. First, the occurence of a microlensing event for a single star is very low (one in a million). We then need to observe very dense fields, such as the Galactic Bulge. Each night, OGLE and MOA surveys analyze the Galactic Bulge to detect events. The second problem is the planetary deviation is very short, one hour to few days for most massive planets. This is why we have to continously observe events and use telescopes all around the Southern Hemisphere. The rapid increase of detection during the last years forces the follow-up telescopes to choose which targets they need to observe. We so decided to develop a new software to make automatically this choice. At the end of this manuscript, we present a statistical study of microlensing parameters from four observational seasons. We expect these results will help to constrain theoritical model of the Milky Way in the future
Alapini, Odunlade Aude Ekundayo Pauline. "Transiting exoplanets : characterisation in the presence of stellar activity". Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/104834.
Pełny tekst źródłaChilders, Joseph M. "A search for transiting exoplanets in eclipsing binary stars". Virtual Press, 2008. http://liblink.bsu.edu/uhtbin/catkey/1398708.
Pełny tekst źródłaDepartment of Physics and Astronomy
North, Thomas Samuel Harry. "Exoplanets and asteroseismology : know the star, know the planet". Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8640/.
Pełny tekst źródłaDe, Kleer Katherine Rebecca. "Photometry and transit-timing analysis for eleven transiting exoplanets". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51598.
Pełny tekst źródłaIncludes bibliographical references (leaves 101-102).
This thesis presents time-series photometry of transits of 11 different extrasolar planets. Observations were conducted with the Fred L. Whipple Observatory 1.2m telescope and the Wise Observatory im telescope, in standard optical bandpasses. The number of transits observed for each planet ranges between one and 20 transits, and differential aperture photometry is performed for each transit observation. For the system TrES-2, this thesis examines 14 different different transit observations. Because of this large quantity of data, the parameters Rp/R., b, a/R., and i are also fitted for with precision using the Markov Chain Monte Carlo technique, and the resultant parameter values are presented. Transit-timing analysis is performed on all systems: CoRoT-2, GJ436, HAT-P-1, HD17156, HD189733, TrES-1, TrES-2, WASP-2, WASP-3, XO-1, XO-2, and XO-3. Transit timing is important both for constraining the orbital period and to search for variations in the transit-to-transit interval that could indicate the presence of an unseen companion planet. The transit center times for nearly all observations are found, and the planetary periods for all systems are calculated. In many cases these periods are determined with much greater precision than previously known. It is found that systems XO-2 and HAT-P-1 are consistent with a constant period, but our data are not conclusive with regards to the other systems.
by Katherine Rebecca de Kleer.
S.B.
Morley, Caroline V. "Measuring transit timing variations of exoplanets using small telescopes". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/114139.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (pages 57-58).
Transits of exoplanets were observed from June 2009 through January 2010. Six transit light curves are presented in this paper for three planets: WASP-10b, WASP- 11/HAT-P-10b, and TrES-3. Measurements of the planetary radii, semi-major axis, transit duration, and period confirmed literature values to within two sigma. Transit timing variations were not observed in these systems, but calculations show that it would be possible to measure transit timing variations induced by large exomoons (greater than about 6 Earth masses) in the WASP-11/HAT-P-10b system. Challenges of exoplanet observation from small telescopes are discussed. It was determined that overall, transit measurements of many exoplanets using small telescopes can be successful and scientifically useful.
by Caroline V. Morley.
S.B.
Garreau, Germain. "Detecting Earth-like exoplanets using high-dispersion nulling interferometry". Thesis, KTH, Tillämpad fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293172.
Pełny tekst źródłaUpptäckten av jordliknande exoplaneter och karakteriseringen av deras atmosfärer är en utmaning man behöver lösa för att bedöma deras beboelighet och närvaron av liv i universum. Om denna utmaning fortfarande inte är löst idag, även i jätteteleskopens tid, beror det främst på den mycket höga kontrasten mellan dessa exoplaneter och deras värdstjärna och också deras närhet. För att övervinna båda dessa begränsningar har en ny metod som kombinerar högdispersionsspektroskopi och nullingsinterferometri föreställts. Idéen är att använda nullingsinterferometrin för att minska stjärnljusemissionen och upptäcka de inre steniga planeterna med hög vinkelupplösning. Spektroskopin med hög dispersion ökar exoplanetens detekterbarhet betydligt vilket gör det möjligt att minska stjärndämpningsbehovet för en jordliknande observation. Vår simulering för en exoplanet som liknar jorden som kretsar omkring Proxima Centauri ger ett tillstånd för stjärndämpningen att ∼10−4 för att upptäcka den. Med tanke på detta villkor kan vi utvärdera oförmågan hos en fotonisk enhet till vårt förfogande för att uppnå sådan prestanda utan att hantera dess begränsningar. Om ett framtida projekt lyckas övervinna dessa begränsningar kan den här enheten vara en del av ett föregångarinstrument på IPAG för att experimentellt visa prestanda för högdispersionsnullningsinterferometri.
Clarke, N. "A novel instrument for the advanced investigation of exoplanets". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1469579/.
Pełny tekst źródłaCunial, Andrea. "Photometric searches for exoplanets and variability in star clusters". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3427233.
Pełny tekst źródłaQuesta tesi è incentrata sull’analisi fotometrica delle curve di luce stellari (LCs), per ricercare stelle variabili e pianeti extrasolari in transito. In particolare, questo studio viene condotto su campi affollati che includono ammassi aperti. Il contesto del mio lavoro è la mappatura fotometrica preparatoria “The Asiago Pathfinder for HARPS-N” (APHN; PI: Bedin), finalizzata alla caratterizzazione degli ammassi aperti (ad esempio M44, NGC752, M35, NGC2158 and M67), al fine di essere impiegata allo spettrografo HARPS-N (acronimo per High Accuracy Radial velocity Planet Searcher for the Northern hemisphere) installato al Telescopio Nazionale Galileo (TNG). Recentemente, la mappatura APHN è stata estesa ad un campionamento addizionale di ammassi aperti che sono stati scelti quali obiettivi per la missione K2, prolungamento della missione Kepler (Howell et al. 2014), allo scopo di creare un catalogo astro-fotometrico di base delle componenti che verranno analizzate con i set di dati delle missioni Kepler e K2 (Libralato et al. 2015a). Altre strumentazioni sono state coinvolte, come ad esempio quelle del progetto SuperWASP oppure quelle del telescopio STELLA1, i cui dati sono stati analizzati in questa tesi. Le ricerche di esopianeti in transito all’interno di ammassi aperti, benchè ardue (van Saders & Gaudi 2011), sono particolarmente utili per limitare le proprietà sia della stella ospitante, sia del pianeta e di svelare il meccanismo di formazione ed evoluzione planetaria (Janes 1996; Fischer & Valenti 2005). La prima parte della tesi è una recensione delle differenti tecniche fotometriche adottate dalla comunità scientifica nella ricerca di esopianeti e, più in generale, della variabilità stellare (capitolo 1), focalizzandosi sulle mappature fotometriche degli ammassi aperti. Una breve recensione sui principali progetti da terra e da spazio viene data alla fine di questo capitolo. Il capitolo 2 analizza le cause degli errori sistematici (“red noise”) e descrive i metodi sviluppati per correggere le curve di luce prima della ricerca di variabilità. Una descrizione delle differenti tipologie di variabilità stellare e degli algoritmi usati per la ricerca di segnali periodici viene data nel capitolo 3. La mia analisi degli ammassi aperti sopra citati è descritta negli ultimi quattro capitoli, partendo da M44 nel capitolo 4. Qui, dopo una descrizione delle attrezzature per le osservazioni, tratto degli algoritmi per la correzione da errori sistematici, della procedura per individuare segnali periodici e dei miei risultati in termini di variabili appena scoperte, includendo uno studio della relazione girocronologica fra la periodicità e il colore della stella. I capitoli seguenti sono organizzati in maniera simile, ma trattano, rispettivamente, di NGC752 (capitolo 5), di M35 & NGC2158 (capitolo 6) e di M67 (capitolo 7).
Umbriaco, Gabriele. "Exoplanets through extreme optics: from PLATO to SHARK-NIR". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3422828.
Pełny tekst źródłaL’Osservatorio di Padova (Istituto Nazionale di Astrofisica) e l’Università di Padova negli ultimi anni sono stati coinvolti massicciamente in progetti dedicati alla ricerca di pianeti extrasolari, sia con strumenti e telescopi da terra che dallo spazio. SHARK-NIR, che sta per “System for coronagraphy with High order Adaptive optics from R to K band – Near-Infrared”, è uno strumento disegnato per cercare e caratterizzare sistemi solari giovani e regioni di formazione stellare nel dominio di lunghezze d’onda del vicino infrarosso. La tecnica devota all’osservazione è quella spettroscopica e dell’immagine diretta. Questo strumento ottico è stato selezionato per la seconda generazione di dispositivi per il Large Binocular Telescope (LBT), con il vantaggio di sfruttare le eccellenti prestazioni del sistema di ottica adattiva di LBT. La correzione di ottica attiva estrema di LBT (XAO), è il requisito necessario di SHARK-NIR per ottenere la migliore cronografia attualmente disponibile con LBT ed è obbligatoria quando l’obiettivo è studiare pianeti poco luminosi che orbitano attorno a stelle brillanti. CHEOPS, che sta per “CHaracterising ExOPlanet Satellite”, è la prima missione spaziale dedicata alla caratterizzazione di piccoli pianeti già noti attorno a stelle brillanti tramite fotometria ad altissima precisione. Si otterranno accurate misure del raggio dei pianeti per i quali la massa è già nota da campagne spettroscopiche con telescopi da terra. Inoltre si conosceranno con precisione i raggi dei nuovi pianeti scoperti dalle campagne di osservazione da terra di nuova generazione basate sulla tecnica dei transiti, fino a pianeti di dimensioni di Nettuno o inferiori. PLATO, che sta per “PLAnetary Transits and Oscillations of stars”, è una missione proposta per il programma di nuovi satelliti di medie dimensioni “Cosmic Vision” dell’Agenzia Spaziale Europea. Il telescopio è focalizzato alla ricerca e caratterizzazione di eso-pianeti attorno a stelle brillanti e vicine al nostro Sole. Il progetto proposto dal consorzio PLATO consiste in un telescopio multiplo, composto da decine di telescopi singoli uguali, per i quali si è sviluppata una soluzione ottica totalmente rifrattiva. Ogni singolo telescopio ha un grande campo di vista (fino a 20 gradi) e una qualità ottica tale da concentrare la maggior parte dell’energia raccolta in un singolo elemento del sensore di immagini. Un tale scopo è raggiungibile applicando una molteplicità di soluzioni, tra cui anche l’uso di elementi ottici asferici. In questa tesi descriverò le attività svolte sia nell’ambito di un progetto spaziale che di uno strumento per telescopio a terra. Il progetto PLATO è stato trattato nell’ambito dell’integrazione, assemblaggio e verifica (AIV) del prototipo della singola unità ottica del telescopio, allo scopo di validare la procedura completa di AIV e le prestazioni in condizioni di volo. Riguardo lo strumento SHARK-NIR si spiegheranno le attività svolte per l’allineamento ottico e la qualificazione finale.
Bounama, Christine. "Thermische Evolution und Habitabilität erdähnlicher Exoplaneten". Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1648/.
Pełny tekst źródłaIn this thesis methods of Earth system analysis are applied to the investigation of the habitability of terrestrial exoplanets. With the help of parameterized convection models for the Earth the thermal evolution of terrestrial planets is calculated. Under increasing central star luminosity the global carbonate-silicate cycle stabilizes the planetary climate. The life span of a photosynthetic-active biosphere existing in a certain temperature interval under adequate CO2 concentration is estimated. The range of orbital distances within which such a biosphere is productive is defined as the photosynthetic-active habitable zone (pHZ) and is calculated. The maximum life span of the biosphere is the point in time when the pHZ of an extrasolar planetary system finally disappears. For super-Earths, i.e. massive terrestrial planets, it is as longer as more massive the planet is and as shorter as more the planet is covered with continents. For super-Earths, which are not pronounced land or water worlds, the maximum life span scales with the planetary mass with an exponent of 0.14. The life span of the biosphere on a planet around K- or M-stars is always determined by the maximum life span and not limited by the end of the main-sequence evolution of the central star. The pHZ approach is applied to the extrasolar planetary system Gliese 581. Accordingly the super-Earth of 8 Earth masses Gliese 581d could be habitable. Based on the presented pHZ concept the Rare Earth Hypothesis established by Ward and Brownlee 1999 is quantified for the Milky Way. This hypothesis claims that complex life may be very rare in the Universe while primitive life is likely common and widespread. Different temperature and CO2 tolerances as well as a different influence on weathering of complex and primitive life forms result different boundaries of the pHZ and a different estimate of the number of planets potentially harboring these different life forms. It arises that planets with complex life might be 100 times rarer than primitive life bearing planets.
See, Wyke Chun Victor. "Stellar magnetism and activity : from stellar interiors to orbiting exoplanets". Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/9602.
Pełny tekst źródłaMocnik, Teo. "Characterization of transiting exoplanets and their host stars by K2". Thesis, Keele University, 2018. http://eprints.keele.ac.uk/5598/.
Pełny tekst źródłaMessenger, Stephen Joseph. "Detectability of biosignature gases in the atmospheres of terrestrial exoplanets". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79156.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 179-182).
Biosignature gases in the atmosphere of an exoplanet provide a means by which we can deduce the possible existence of life on that planet. As the list of possible biosignature gases is ever growing, the need to determine which molecules provide the best opportunities for detection grows as well. One way to explore these systems is through modeling radiative transfer via transmissivity as light travels from the parent star, through the atmosphere of the planet, and then impacts a detector located at Earth. As the light travels through the planetary atmosphere, it acquires molecular features from the planet due to the composition, temperature, and pressure structure of the atmosphere. By adding synthetic noise to the modeled transmissivity spectra, I determine the detectability of a range of atmospheric mixing ratios for ten biosignature gases from the HIgh-resolution TRANsmission molecular absorption (HITRAN) database: oxygen, ozone, methane, nitrous oxide, methyl bromide, methyl chloride, hydrogen sulfide, carbonyl sulfide, phosphine, and sulfur dioxide. The deep investigation of the HITRAN biosignature gases in this study is possible due to the ability to properly map their absorption cross sections to varying temperatures and pressures. For each of the above HITRAN molecules, I analyze alternative spectral features for detection in order to emphasize the importance of and determine the ability for multiple band detection of biosignature gases. Water vapor (though not a biosignature gas) is included in order to study its potential for spectral masking. Though I nd that each of the above HITRAN gases could be detected in exoplanet atmospheres if that molecule has a large enough atmospheric mixing ratio, an Earthsize planet with an Earth-like atmosphere located at 35.45 parsecs would only allow for discernible biosignature features from ozone, nitrous oxide, and methane in the infrared wavelength region. Sixteen additional (and non-standard) biosignature gases included in this study do not have absorption cross sections that are currently mapable to alternative temperatures and pressures. These sixteen biosignature gases are acetaldehyde, acetone, benzene, carbon disulfide, dimethyl disulfide, dimethyl sulfide, dimethyl sulfoxide, ethanol, ethyl mercaptan, fluoroacetone, isoprene, methyl ethyl ketone, methyl mercaptan, methyl vinyl ketone, thioglycol, and toluene. To circumvent the nonmapability of the absorption cross sections to dierent temperatures and pressures, I use the detectivity calculations and the absorption cross sections from ozone, methane, and nitrous oxide to estimate the threshold atmospheric mixing ratios for the detection of the sixteen non-standard biosignature gases with a 35 m telescope, 100 hours of observation, and a target distance of 35.45 parsecs. The combination of the threshold atmospheric mixing ratios calculated for these sixteen non-standard biosignature gases with the results from the HITRAN biosignature gases investigated in this study demonstrate that an atmospheric gas will require a mixing ratio in the tens to hundreds of ppm to be detectable above a 5[sigma] level with a 35 m telescope, an observation time of 100 hours, and a target distance of 35.45 parsecs. Keeping with the theme of multi-wavelength detection, I end the analysis of the sixteen non-standard biosignature gases by proposing potential spectral feature wavelengths for each gas based on their molecular absorption cross section spectral profiles. As many biosignature gases have molecular features at longer wavelengths than the traditional IR region, I investigated the technological requirements for detecting biosignature gas spectral features in one of the low-signal long-wavelength regions, the millimeter. Though the investigation into the millimeter region reveals unrealistic technological demands for the successful detection of the case study, oxygen, I use the analysis as a platform to introduce the theoretical concept of observing future targets with multiple next-generation telescopes stationed in a matrix in order to produce the same observational ability of a larger (and more distant future) telescope. While interferometric investigations into millimeter spectral features are improbable in the near future, the use of interferometry with next generation instruments may allow for investigations in the 10 - 30 [mu]m region, thereby opening alternative wavelengths for biosignature gas detection. Since this theoretical interferometry idea relies on the ability to increase the signal-to-noise ratio (SNR) of the observations, I investigated the interaction between telescope aperture size and observation duration on the detectability (i.e. SNR) of biosignature gases in reference to finding a middle ground between these two system parameters for both a 6 m and 35 m telescope. Unfortunately, a 6 m telescope does not provide a large enough collecting area to increase the SNR sufficiently enough to detect atmospheric gases. For futuristic telescope designs, though a 20 m telescope (or nine JWSTs working together to achieve the same collecting area) would begin to discern some biosignature gas features from the continuum (for high biosignature gas atmospheric abundances), a 35 m class telescope (or equivalent interferometric telescope array) should be the minimum aperture size considered for biosignature gas detection in transmissivity spectroscopy.
by Stephen Joseph Messenger.
S.M.
Waldmann, I. P. "Of 'cocktail parties' and exoplanets : data analysis in exoplanetary spectroscopy". Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1349611/.
Pełny tekst źródłaBeichman, Charles, John Livingston, Michael Werner, Varoujan Gorjian, Jessica Krick, Katherine Deck, Heather Knutson i in. "SPITZER OBSERVATIONS OF EXOPLANETS DISCOVERED WITH THE KEPLER K2 MISSION". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621243.
Pełny tekst źródłaMulders, Gijs D., Ilaria Pascucci, Dániel Apai, Antonio Frasca i Joanna Molenda-Żakowicz. "A SUPER-SOLAR METALLICITY FOR STARS WITH HOT ROCKY EXOPLANETS". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622435.
Pełny tekst źródłaRajpaul, Vinesh Maguire. "Gaussian process tools for modelling stellar signals and studying exoplanets". Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:4587b280-f93c-4847-915a-ab33f6a55a01.
Pełny tekst źródłaCaldas, Anthony. "Étude des biais observationnels induits par le caractère tridimensionnel des atmosphères d’exoplanètes". Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0439/document.
Pełny tekst źródłaTransmission spectroscopy provides us with information on the atmospheric properties at the limb, which is often intuitively assumed to be a narrow annulus aound ther planet. Consequently, the few recent studies on the effect of atmospheric horizontal heterogeneities on transmission spectra have used approaches sensitive to variations along the limb only. Here we demonstrate that the region probed in transmission – the limb – actually extends significantly toward the day and night sides of the planet. Consequently we show that thestrong day-night thermal and compositional gradients expected on synchronous exoplanets create sufficient heterogeneities across the limb to result in important systematic effects on the spectrum and bias its interpretation. To quantify these effects, we developed a 3D radiative transfer model able to generate transmission spectra of atmospheres based on 3D atmospheric structures, whether they come from a Global Climate Model or more parametrized models. We first apply this tool to a simulation of the atmosphere of GJ 1214 b toproduce synethic JWST observations and show that producing a spectrum using only atmospheric columns at the terminator results in errors greater than expected noise. This demonstrates the necessity of a real 3D approach to model data for such precise observatories.Second, we investigate how day-night temperature gradients cause a systematic bias in retrieval analysis performed with 1D forward models. For that purpose we synthesize a large set of forward spectra for prototypical HD209458 b and GJ 1214 b type planets varying the temperatures of the day and night sides as well as the width of the transition region. We then perform typical retrievalanalyses and compare the retrieved parameters to the ground truth of the input model. This study reveals systematic biases on the retrieved temperature (found to be higher than the terminator temperature) and absorber abundances. This is due to the fact that the hotter dayside is more extended vertically and screens the nightside—a result of the nonlinear properties of atmospheric transmission.These biases will be difficult to detect as the 1D profiles used in the retrieval procedure are found to provide an excellent match to theobserved spectra based on standard fitting criteria (chi2, posterior distributions). This fact needs to be kept in mind when interpretingcurrent and future data
Ballard, Sarah. "In Pursuit of New Worlds: Searches for and Studies of Transiting Exoplanets from Three Space-Based Observatories". Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10229.
Pełny tekst źródłaAstronomy
Минак, В. І., i О. О. Орлова. "Дослідження процесів та методів в області пошуку та вивчення екзопланет". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/14082.
Pełny tekst źródłaHicks, Brian Andrew. "Nulling interferometers for space-based high-contrast visible imaging and measurement of exoplanetary environments". Thesis, Boston University, 2012. https://hdl.handle.net/2144/32883.
Pełny tekst źródłaPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
This dissertation presents the legacy, theory, design, characterization, and application prospects of a fully symmetric monolithic nulling interferometer (nuller). A nuller's function is to destructively interfere light originating from a bright, on-axis, unresolved source in order to lower its contrast with faint, off-axis sources of light in the field of view. The primary application lies in astronomical instrumentation, serving as an enabling technology for directly imaging exoplanets and measuring exozodiacal dust and debris disks, the planetary system evolutionary components around nearby stars. Typical on-sky planet/star flux ratios are 1:109 or less in the visible. Mitigating this contrast is key to spectroscopic study of exoplanets, which aims to characterize exoplanetary atmospheres and potentially locate biosignatures on exo-Earths. Within the past decade, adaptive optics-equipped breadboard demonstrations of nullers and other coronagraphs have shown the capability to image nearby (< 30 lightyears) extrasolar analogs to Jupiter with a 0.5 meter diameter telescope in the visible. The quiet laboratory environments that have been produced to demonstrate this capability do not reflect those of typical ground-based observatories where thermal drifts perturb optical alignment and atmospheric turbulence perturbs the source wavefront. Space-based platforms circumvent the atmosphere problem, but are still subjected to thermal instabilities and their associated risks. Robust optical systems must be designed and flight-tested in order to address such risks and provide grounds for their inclusion in the design of future exo-Earth imaging satellites. Sub-orbital platforms such as sounding rockets and high-altitude balloons provide a rapid, lowcost means of providing heritage for such optical systems while also delivering significant scientific results. The primary risk inherent with these platforms are harsh transient environmental conditions, for which, similar to an orbital platform, robust optical systems are necessary. A novel feature of the nuller described in this work is its monolithic design, which greatly enhances optical stability, the primary obstacle plaguing all high-contrast imaging efforts. Additional design benefits include theoretical achromatic performance and an inner working angle that is 2-4 times smaller than other coronagraph designs, enabling its use with proportionally smaller telescopes.
2031-01-01
Stevenson, Kevin. "Detecting and Characterizing Exoplanets: The GJ 436 and HD 149026 Systems". Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5518.
Pełny tekst źródłaPh.D.
Doctorate
Physics
Sciences
Physics; Planetary Sciences
Bartilsson, Alexander. "On the possibility of nding exoplanets usinggravitational lensing of radio backgrounds". Thesis, Stockholms universitet, Institutionen för astronomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-166296.
Pełny tekst źródłaHu, Renyu Ph D. Massachusetts Institute of Technology. "Atmospheric photochemistry, surface features, and potential biosignature gases of terrestrial exoplanets". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82168.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 269-304).
The endeavor to characterize terrestrial exoplanets warrants the study of chemistry in their atmospheres. Here I present a comprehensive one-dimensional photochemistry-thermochemistry model developed from the ground up for terrestrial exoplanet atmospheres. With modern numerical algorithms, the model has desirable features for exoplanet exploration, notably the capacity to treat both thin and thick atmospheres ranging from reducing to oxidizing, and to find steady-state solutions starting from any reasonable initial conditions. These features make the model the first photochemistry-thermochemistry model applicable for non-hydrogen-dominated thick atmospheres on terrestrial exoplanets. Using the photochemistry model, I explore the compositions of thin atmospheres on terrestrial exoplanets controlled by surface emission and deposition of gases. Highlights of my findings are: (1) oxygen and ozone may build up in 1-bar CO2 atmospheres to levels that have conventionally been accepted as unique signatures of life, if there is no surface emission of reducing gases; (2) volcanic carbon compounds (CH4 and CO2) are likely to be abundant in terrestrial exoplanet atmospheres; but volcanic sulfur compounds (H2S and SO2) are chemically short-lived and therefore cannot accumulate in virtually any types of terrestrial exoplanet atmospheres. Also using the photochemistry model, I explore the ranges of molecular compositions of thick atmospheres on terrestrial exoplanets. I find that carbon has to be in the form of CO2 in a H2-depleted water-dominated atmosphere, and that the preferred loss of light elements from an oxygen-poor and carbon-rich atmosphere leads to formation of unsaturated hydrocarbons (C2H2 and C2H4). These results imply that chemical stability has to be taken into account when interpreting the spectrum of a super Earth/mini Neptune like GJ 1214b. Another intriguing category of terrestrial exoplanets is bare-rock exoplanets. I present the first theoretical framework to compute disk-integrated spectrum from a bare-rock exoplanet, taking into account the reflectivity and emissivity of solid minerals on the surface. I find that silicate surfaces lead to prominent spectral features in the 8 - 13 [mu]m range, detectable by mid-infrared spectroscopy using transit. Therefore transit spectroscopy is an independent method to confirm the rocky nature of an exoplanet.
by Renyu Hu.
Ph.D.
Rogers, Leslie Anne. "Formation, structure and habitability of super-Earth and sub-Neptune exoplanets". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77254.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 197-205).
Insights into a distant exoplanet's interior are possible given a synergy between models and observations. Spectral observations of a star's radial velocity wobble induced by an orbiting planet's gravitational pull measure the planet mass. Photometric transit observations of a planet crossing the disk of its star measure the planet radius. This thesis interprets the measured masses and radii of super-Earth and sub-Neptune exoplanets, employing models to constrain the planets' bulk compositions, formation histories, and habitability. We develop a model for the internal structure of low-mass exoplanets consisting of up to four layers: an iron core, silicate mantle, ice layer, and gas layer. We quantify the span of plausible bulk compositions for low-mass transiting planets CoRoT-7b, GJ 436b, and HAT-P-11b, and describe how Bayesian analysis can be applied to rigorously account for observational, model, and inherent uncertainties. We present a detailed case study of GJ 1214b, the first exemplar of a new class of volatile-rich super-Earth exoplanets. At 6.5 Mo and 2.7 Ro, GJ 1214b must have a gas layer to account for its low mean density. We present three possible scenarios for the origin of the gas layer on GJ 1214b: direct accretion of H/He gas from the protoplanetary nebula, sublimation of ices, and outgassing of volatiles from a rocky interior. We next explore the low-density extreme of the mass-radius relations for volatilerich super-Earth exoplanets. Using models of planet formation, structure, and survival, we constrain the minimum plausible planet mass for a measured planet radius and equilibrium temperature. We explore both core-nucleated accretion and outgassing as two separate formation pathways for Neptune-size planets with voluminous atmospheres of light gases. Finally, we present a practical method to assess whether a hydrogen-rich sub-Neptune planet with measured mass and radius could potentially harbor a liquid water ocean. Using a one-dimensional radiative-convective model of energy transport through water-saturated hydrogen-rich envelopes, we constrain the combinations of planet properties (mass, radius, equilibrium temperature, intrinsic luminosity) that are conducive to liquid water oceans. The pace of low-mass exoplanet discoveries is poised to accelerate, and this thesis will contribute to constraining the interior properties of newfound planets.
by Leslie Anne Rogers.
Ph.D.