Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"orbital periods"”.
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Observational studies of highly evolved cataclysmic variables
… CVs to initially evolve from longer to shorter orbital periods until a minimum period is reached (? 80 minutes). At roughly this stage, the donors becomes degenerate, expand in size, and the systems move towards longer orbital periods. Theory predicts that 70% of all CVs should have passed their …
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Effect of aerodynamics on the perturbations of a space vehicle orbit
… Encke’s perturbative procedures were used during orbital periods and Cowell’s integration procedures during thrust and reentry periods.
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Orbital decay of hot Jupiters : coefficients of nonlinear tidal coupling as a function of the stellar host type
… masses (around a Jupiter mass) and tight orbits (orbital periods P </~ 3 days). These tides remove orbital energy and angular momentum, causing the planet's orbit to decay. The rate of decay depends on the detailed structure of the host star through the coefficients of nonlinear tidal coupling. …
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Investigations of close-in exoplanets : starspot transits, and ultra-short period planets
… the angle between the spin axis of the star and orbital plane of each of the planets. In our solar system, the obliquity of all planets is within a few degrees of zero, a natural consequence of the standard theory of planet formation, in which a rotating envelope of gas collapses into a …
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Planet formation and evolution in our Solar System and beyond
… in size between Earth and Neptune with orbital periods less than 100 days are abundant in our galaxy. Concurrently, spacecraft missions to small primitive bodies in our solar system have yielded valuable insights into conditions in the early solar system. This thesis addresses questions …
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Identifying and Analyzing Multi-Star Systems Among TESS Planetary Candidates Using Gaia
… systems were observed to have slightly larger orbital periods, yet smaller planet radii and mass.</p>
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Superhumps in AM Canum Venaticorum stars
… disc to a DB white dwarf. Under this model, the orbital periods of the AM CVn systems are in the range 1000 - 3000 s. The AM CVn systems show many of the accretion disc-related phenomena that are observed in non-magnetic (hydrogen-rich) cataclysmic variables. Five of the six systems show …
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Accretion processes in cataclysmic variable stars: insights from optical transient surveys
… Observations of 7 outbursting AM CVn stars with orbital periods ranging from
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Post-common-envelope binary central stars of Planetary Nebulae in the OGLE-IV survey
… terms of our understanding of PNe evolution. The orbital distribution is derived and compared against current orbital distribution for binary CSPNe, with most binaries from the distribution exhibiting orbital periods less than a day. A binary fraction estimate of 6% is presented and possible cases …
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Optical and X-ray studies of Be/X-ray binaries in the Small Magellanic Cloud
… the RXTE light curves. This has culminated in an orbital solution for SXP18.3 as well as measured orbital periods for SXP2.37, SXP172 and SXP202B. Through detections of quasi-periodic variations in the optical light curves, the details of interactions taking place between the Be star’s …
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The Effect of Tidal Interactions On Hot Subdwarf B Stars and Their Pulsations
… of which are found in close configurations with orbital periods of $10\,$d or less. These short period systems are formed by common envelope evolution. In order to estimate the companion masses in these predominantly single-lined systems, tidal locking has frequently been assumed for sdB binaries …
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Coupled Dynamics in the Cislunar Region and Spacecraft Attitude Prediction in a Higher-Fidelity Model
… symmetries, for multiple revolutions or single orbital periods, for non-periodic trajectories, and for multiple starting epochs of the full ephemeris simulation. Analysis of these results is intended to help determine when the CRF3BP is most useful to advance cislunar mission planning of the …
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MeerKAT observations of novalike cataclysmic variables
… the sample: V5662 Sgr and LSIV -08 3. I obtain orbital periods for these two systems that are consistent with previous measurements in the literature.
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Eclipsing Binaries and Period Changes in the SuperWASP Archive
… and specifically to search for evidence of orbital period variations. The short cadence and long time base of SuperWASP light curves make them highly suitable for variable star research of many kinds, and the size of the database (~30 million objects) allows for the discovery and study of …
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Nonlinear hydrodynamic instability and turbulence in eccentric astrophysical discs
… the eccentricity on the timescale of 50 to 100 orbital periods, and so is a promising mechanism for balancing the exponential growth of eccentricity from the eccentric Lindblad resonances.
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X-ray spectroscopy of low-mass X-ray binaries
… on results from the subset of LMXBs with orbital periods less than an hour, known as ultracompact binaries. Previous low-resolution X-ray spectra of four systems (4U 0614+091, 2S 0918-549, 4U 1543-624, and 4U 1850-087) all contain a broad residual near 0.7 keV which had been attributed to …
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Theoretical statistics of zero-age cataclysmic variables
… of the mass ratios and the distribution of the orbital periods in cataclysmic variables which are forming at the present time are calculated. These systems are referred to as ""zero-age cataclysmic variables"". The results show that 60% of the systems being formed contain helium white dwarfs and …
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A New Era of Observational Capability at Ritter Observatory: Spectropolarimetry from Exoplanets to Circumstellar Disks and Beyond
… wavelength dependent variable polarization with orbital phase. While the variability claimed in the literature is below the noise limits of our observations, an interesting and yet unexplained increase in the polarization level occurred in one of our observations. This higher than expected signal …
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Detection and Characterization of Hot Super-Earth Exoplanets
… are exoplanets characterized by short orbital periods and surface temperatures high enough to melt silicate rock. These planets lack any solar system analog, and are the most accessible small, rocky exoplanets available to study today. In this thesis, I develop a holistic understanding …
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The orbital dynamics and long-term stability of planetary systems
… population of low-mass exoplanets with short orbital periods has been discovered using the transit method. At least 40% of these planets are actually part of compact systems with more than one planet. The closeness of the planetary orbits in these multi-planet systems leads to strong dynamical …
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