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 31 for “"radial velocities"”.
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Precise radial velocities and simultaneous magnetic flux estimates from intensity spectra
The Radial Velocity (RV) community has made tremendous leaps forward in the past decades detecting and characterising ever smaller and lighter exoplanets. In recent years, this trend has been broken as planet-induced RV signals smaller than 1 m/s are drowned out by the stars' activity. The …
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Characterization of exoplanetary systems combining transit timing techniques and radial velocities: From secular perturbations to resonant chains
… Timing Variations (TTVs) and high-precision Radial Velocity (RV) measurements, I provide crucial constraints on planetary masses, orbits, and system architectures. I first explored tidal orbital decay in ultra-hot Jupiters through the analysis of WASP-12 b, using 12 years of ground-based …
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Searching for planets
As part of a larger program precise radial velocities (PRVs) have been obtained by useof a hydrogen fluoride (HF) cell over the period 1980 to 1992, for twenty-one dwarf andsubgiant stars (luminosity classes IV and V) together with eleven giants and supergiants(luminosity classes I, II, and III). A …
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A Feasibility Study for Using the ERAU Échelle Spectrograph to Improve Orbital Parameters of Spectroscopic Binary Systems
… Aeronautical University (ERAU) to obtain radial velocities of spectroscopic binary stars, and establishes a software pipeline to obtain their orbital parameters. This was done by looking at the double-lined binaries HD 205539 and Pegasi, as well as the single-lined binary Andromedae. …
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Secondary Clarifier Modeling: A Multi-Process Approach
… of secondary settling tanks. The gravity induced radial velocities in the sludge blanket are higher than the radial velocities of the scraper in the region near the hopper, therefore the blades are not highly effective in conveying the solids in this region.
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Development and Testing of a New Method for Velocity-Selecting White Dwarfs from Gaia by Galactic Population
… with proper motions of these stars, though not radial velocities. We have developed a scheme to complete the velocity vector by estimating radial velocities in terms of the proper motion, and assigning stars by probability of membership to the thin disk, thick disk, or halo population. We then …
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Kinematics of Nearby Subdwarfs And the Luminosity Function of the Galactic Thick Disk
… and Tycho2 proper motions were combined with radial velocities and metallicities from CLLA. The kinematical behavior is discussed in particular in relation to their metallicities. For stars with metallicity -1.0<[Fe/H]<-0.4, the velocity distribution represent the thick disk population. We …
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Optical study of F, G and K stars in the ROSAT All-Sky Survey
… classes, absolute magnitudes, distances, radial velocities, projected rotational velocities, effective temperatures, Lithium abundances. I compare the X-ray parameters of my sample stars with those of a similar sample, detected by the Einstein Observatory during its Medium Sensitivity …
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The dynamical state of a young stellar cluster
… is considered, with emphasis on the L1688 cloud. Radial velocities are derived for 32 YSOs, with some being multi-epoch, using Markov-Chain Monte Carlo routines based upon the package <i>emcee</i>. Sources are chosen based upon their spectral index to focus on the earlier stages of star formation, …
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The Three-Dimensional Turbulent Boundary Layer on a Rotating Disk
… that leads to turbulence. The tangential and radial velocities were measured using hot-wire anemometry. The mean flow, turbulent intensity, energy spectra, skewness and kurtosis of the flow have been analyzed and compared with 2DTBL measurements. It was found that the measurements collapsed …
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Kinematics of T Tauri stars in nearby star forming regions
… Where available, Hipparcos parallaxes and radial velocities are combined with the proper motions to calculate space velocities and velocity dispersions. In the Scorpius-Centaurus association, the favourable geometry allows for the determination of kinematical distances. A large fraction of …
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Evolution of galaxies in compact groups
… state of these groups. The new data consist of radial velocities and surface photometry of individual galaxies and velocity dispersions and complete membership information for the groups. The results of this thesis strongly suggest that most Hickson Compact Groups are physically associated …
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Time Series Analysis of the A0 Supergiant HR 1040
… and compared, including line equivalent width, radial velocities and Stromgren photometric indices.</p><p>Typical of late B- and early A-type supergiants, HR 1040 has a highly variable stellar wind including High Velocity Absorption (HVA) events. The star was found to have an active phase with …
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The properties of the SC stars and chemical composition of UY centauri
… derived from the line list is used to find the radial velocities of all the stars. A solar model atmosphere, with pure absorption as the method of line formation, is used to derive astrophysical log gf values from solar equivalent widths and meteor abundances. The model atmosphere also shows, …
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Wind flow characteristics of multi-vortex tornadoes and their wind effects on residential houses
… velocity of tornadoes from the tangential and radial velocities (extracted from the radar measured velocities) is developed in order to simulate tornadoes in a more precise manner. Second, a multi-vortex tornado is simulated, and its wind flow characteristics are investigated and compared with …
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Kinematic and Abundance Gradients in the Galactic Disk
Radial velocities and DDO and BV photometry of 364 G and K stars in the galactic center and anticenter directions have been obtained for the purpose of investigating the gradients of abundance and velocity dispersion in the galactic disk. The abundance gradient found for these stars is d (Fe/H) /dR …
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Heartbeat Stars and the Ringing of Tidal Pulsations
… the bayes-todcor software, which generates radial velocities and fundamental stellar parameters from spectra using a combination of emcee and todcor; and software created for modelling heartbeat stars, which is a combination of phoebe, emcee and my own codes. One of the features added to the …
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Structure of an east coast cyclone derived from airborne radar and model diagnostics
… stable and highly sheared environment with radial velocities of 1 m s-1 upward to 4 m s-1 downward, corresponding to updrafts and downdrafts of ~ 2-3 m s-1. Updrafts of similar magnitude were observed in a marginally stable, sheared environment at or near cloud top. Atmospheric temperature …
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The properties of transiting exoplanets
… final pieces of work of the thesis focus more on radial velocities, rather than transit events. From a transit search of K2 M-dwarfs, I compiled a list of so-called “monster” planet candidates – Jupiter-sized planets orbiting M-dwarfs. I plan obtain high-resolution spectra of these targets in …
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Exploring dark matter locally via a hierarchy of stellar systems
… such as MACHOs. Extending earlier work we use radial velocities measurements to validate a number of objects in the existing sample of wide halo binary candidates, and with the updated sample we study the constraints on MACHOs, arriving at the conclusion that the current wide binaries sample …
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