More than 40 different molecules have been observed in Interstellar space within the Galaxy. Many of these molecules are seen near hot OB-type stars whose far-ultraviolet emission is intense. Laboratory spectroscopy of such molecules will lead to a better understanding of their astrophysical behaviour, in particular Celestial Masers. This thesis is preoccupied with the spectroscopy of H$_{2}$O, D$_{2}$O, OH, CO, and C$_{2}$H$_{2}$ in the region 1200$\AA$-400$\AA$ and absolute absorption coefficients are derived for CO and C$_{2}$H$_{2}$ using the Thomas-Reiche-Kuhn Sum Rule. A possible Rydberg series of OH was observed, converging to a first ionisation potential of 13.36 eV and a likely inner shell two-electron resonance detected in the ionisation continuum of D$_{2}$O at 415$\AA$. Both a synchrotron and a laser produced plasma continuum source were used for absorption measurements and the advantages of each source were compared. Experiments were undertaken to examine the radiation properties of laser produced plasmas with a view to their general use as far-ultraviolet continuum sources and a computer program was written to predict their net photon emission by Bremsstrahlung processes, with some success. Optoacoustic spectroscopy was considered as a possible technique in the far-ultraviolet with a synchrotron source; its theory was extended to include ionisation and dissociation of molecules. However, optoacoustic experiments attempted were unsuccessful because of insufficient light intensity and excessive background noise near the synchrotron.

Le milieu interstellaire (ISM) représente un fraction mineur de la matière de la Voie Lactée, mais joue un rôle clefs dans l'évolution et la structure galactique. La majorité des constituants du ISM a été identifiée grâce à leur émissions ou absorptions, mais une catégorie d'absorption, les "bandes interstellaires diffuses" (DIBs), n'ont pas des particules absorbantes identifiées. En particulier, il y a une DIB centrée à 862 nm dans le intervalle spectroscopique du Radial Velocity Spectrometer (RVS), un des instruments des la mission ESA Gaia. La première partie de ma thèse est reliée à la construction de ce future catalogue et son usage potentiel. J'ai développé un code de profile fitting adapté à la DIB "Gaia" et à l'instrument RVS. Je présente dans ma thèse l'estimation de DIB mesurable.La second partie de ma thèse est en relation aux cartes 3D du ISM. J'ai focalisé sur l'usage potentiel des DIBs pour le mapping. J'ai fait la première tomography basée sur des données composées, extinction et DIB. J'ai tourné des inversions parallèles des extinctions et DIB pour les mêmes targets stellaires, et comparé les distributions. J'ai développé une technique exprès pour le massive dataset, appelée "technique topographique hiérarchique" et j'ai appliqué cet technique aux nouveau catalogue de 30 millions des mesures d'extinction basé sur Gaia. Finalement, j'ai utilisé des spectres au sol pour extraire soit les vitesses soit la colonne des matériaux interstellaire avec du profile-fitting et j'ai participé aux premiers steps d'une carte cinématique 3D du ISM. / The Interstellar Medium (ISM) represents a small fraction of the Milky Way matter, but it plays a fundamental role because it governs the galactic evolution and its structure.Most of the ISM gaseous constituents have been identified through their emission or absorption characteristics, however, the "diffuse interstellar bands" (or DIBs), still has no counterpart in absorbing species.A favourable situation is the presence of a DIB (with central wavelength 862 nm) within the spectral interval of the Radial Velocity Spectrometer (RVS), one of the instruments of the ESA Gaia mission. The first part of the work presented in this document is directly related to the construction of this future catalog and its potential use.I have developed a profile fitting code adapted to the emph{Gaia} DIB and to the RVS instrument. I estime in my thesis how many DIBs will be measured.The second part of this thesis is related to the three-dimensional (3D) mapping of the ISM. I made the first tomography based on composite data, both extinctions and DIBs and showed this is a viable way. I ran parallel inversions of two extinction and DIB datasets for the same target stars and compared the distributions.The full 3D tomographic inversion technique in this case requires an unrealistically large computing time. I have developed a technique and I have applied it to a new catalog of 30 millions of extinction measurements based on Gaia.Finally, I used ground-based stellar spectra to extracted radial velocities and columns of IS absorbing species and participated to the first step of a "kinematic" 3D map of the ISM.

The interaction between the solar wind and the partially ionized gas of the local interstellar medium (ISM) creates a bubble known as the heliosphere. Classically, the shape of the heliosphere has been regarded as comet-like, with a long tail pointed in the direction opposite the Sun’s motion through the ISM. In this view, the solar magnetic field was assumed to have a negligible effect on the global structure of the heliosphere. Recent advances in numerical modeling have revealed the importance of the solar magnetic field in its ability to confine and collimate the solar wind plasma, and the shape of the heliosphere has been called into question. Energetic neutral atoms (ENAs) are created throughout the heliosphere via charge exchange. The separate contributions of the solar magnetic field topology and the solar wind structure to ENA observations is largely unexplored. The Interstellar Boundary Explorer (IBEX) has been providing a global perspective of the heliosphere through ENA maps with energies ranging from 0.2 to 6 keV. In this dissertation, three-dimensional magnetohydrodynamic simulations of the heliosphere are used as input to an ENA model designed to produce synthetic ENA maps. I compare modeled ENA maps with IBEX observations to investigate how different heliospheric conditions and properties affect ENAs created in the heliosphere, and therefore how ENA observations can be used to understand the heliosphere. First, I investigate the effect of the solar wind collimation by the solar magnetic field on ENA maps in the case of a solar wind without latitudinal variation. I find that even in the absence of variations of the solar wind, two lobes of strong ENA flux form at high latitudes, similar to what is observed by IBEX at high energies. Second, I test the effect of a latitudinally-varying solar wind on ENAs both with and without the inclusion of the solar magnetic field. I show that the latitudinal variations of the solar wind during solar minimum creates a structured ENA profile with latitude, corresponding to the profile observed at 1 AU, but that the solar magnetic field significantly enhances ENA flux in the region where the solar wind is confined. Lastly, I investigate the effect of the solar cycle on ENAs and how changing solar wind conditions (e.g. density, temperature, velocity) affect the heliosphere over time. I demonstrate that, given changes in the solar cycle, there is a significant evolution in the modeled ENA flux due to the changes in the solar wind profile and the solar magnetic field, which is also seen by ENA observations.

Ion chemistry has become increasingly important in the evolution of the chemical inventory of extraterrestrial environments. Isomers of ions have also come to play an important role as, in many instances, the cold environments in the interstellar medium and high layers of planet and satellite atmospheres do not supply enough energy to overcome isomerization barriers and the isomers effectively act as separate molecules.  In this licentiate thesis, several studies of the [CH3N]+ isomers are presented. Reactivity studies of the two isomers, the methanimine radical cation (H2CNH+) and aminomethylene (HCNH2+) with hydrocarbons C2H4, C2H2 and CH4, and IRPD spectroscopy of both species have been performed. Complimentary ab initio calculations aid in the determination of formation pathways of observed product channels and in the assignment of the vibrational bands seen in the IRPD spectrum. The results show that reaction pathways of the two isomers generally involve adduct formation followed by hydrogen ejection where the product or pathway is dependent on the ingoing reactant isomer. The IRPD spectrum allows identification of the different isomers via vibrational transitions. Isomer generation by electron ionization favours methanimine cation production with an abundance of 70% while with VUV photoionization it is possible to selectively produce isomers. It is concluded that isomerism must be considered when investigating the chemical environment of interstellar objects.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20180号 / 理博第4265号 / 新制||理||1613(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 太田 耕司, 准教授 栗田 光樹夫, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

The James Webb Space Telescope (JWST) is a next-generation space telescope that will be capable of making transformative observations of planetary transits. As its launch date grows ever closer, it becomes imperative that astronomers have access to accurate simulations of JWST observations in order to best plan observations and devise data analysis pipelines. Unfortunately, available simulation tools do not provide the most accurate or realistic simulations, including noise and systematic errors. In this thesis, I present an open-source time-domain simulator of planetary transits that is capable of accurately modeling these effects in observations made by JWST.

For my MFA thesis exhibition, I have collected ideas surrounding events that happened in the past and combined them with the ceramic work I have made in the three years of my master's program at Brigham Young University. I have grouped visual elements from Buck Rogers and other Futro (retro-future) pop-culture with ideas surrounding the Voyager Interstellar Mission and the compiling of the Golden Record. Combining these elements in an installation, will create an environment where people can reflect on things they have "already seen" and envision a brighter future. For that reason I playfully call the show Day Jaw Boo, a re-collection and allow the viewers to enter a dream-like-reality-stage of déjà vu.

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Theory and methods of processing speckle interferometry data from close visual binary stars are presented and implemented. The effects of the optical systems used for observing close visual binary stars are explained and simulated from both the geometrical and physical optical viewpoints. The atmospheric phase distortion and shot noise responsible for the observed speckle patterns are simulated. The deconvolution technique originally presented by Labeyrie is implemented to extract astrometric data from close visual binary stars. This method is applied to both simulated and experimental data from Kitt Peak National Observatory as validation. Parts of the deconvolution process are optimized to allow for near real time calculations in an automated observatory.

In October 2017, the first interstellar object, designated 1I/2017 U1 and more commonly referred to as Oumuamua, was detected passing through our solar system by the Pan-STARRS telescope, followed recently by the detection of 2I/Borisov in August 2019. These detections came much sooner than thought possible, and have redefined our understanding of the population of interstellar objects. With the construction of the next generation of powerful observatories, future detections are estimated to occur as frequently as two per year, and while there is significant scientific understanding to be gained from observing these objects remotely, a spacecraft sent to intercept one might be the only way to collect up-close, detailed information on the composition of extra solar object. The ideal mission scenario would be a combination flyby and impact as performed and proven feasible by the Deep Impact encounter with the comet Temple 1. A study has already been done showing that trajectories to interstellar objects are feasible with current chemical propulsion and a “launch on detection” paradigm, with an estimated 10 year wait time between favorable mission opportunities, assuming future detection capabilities. However, while a trajectory to one of these objects might be feasible, accurately performing a flyby and impacting an object with a hyperbolic orbit presents unprecedented navigational challenges. Spacecraft-target relative velocities can range between 10 km/s to 110 km/s with high phase angles between 90° and 180°. The goal of this thesis is to determine the required navigation hardware – an optical navigation camera and attitude determination system – which could provide high mission success probability for many potential encounter scenarios. This work is performed via a simulation program developed at the Jet Propulsion Laboratory that generates simulated images of a target during the terminal guidance phase of a mission, and feeds them into the algorithms behind autonomous navigation software (AutoNav) used for the Deep Impact mission. Observations are derived from the images and used to perform target-relative orbit determination and calculate correction maneuvers.