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 10 of 10 for “"stellar rotation"”.
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An analysis of beta cephei stars in NGC 3293 and the effects of stellar rotation
… predictions, including the effects of rotation. The results imply a preference for first and second overtone quadrupole (l=2) pulsation in these stars, while a weak relationship between stellar mass and pulsation overtone is identified. One of the stars is identified as a member of an …
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Unearth: Revealing the Effects of Stellar Activity on Exoplanet Host Stars
… thesis, I investigate the effect activity has on stellar spectra, using HARPS data of the well observed K1 V star α Centauri B. I compare spectra from high- and low-activity periods (as traced by log R′HK) of α Cen B. I produce ‘relative spectra’ by dividing the high-activity spectra by a …
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Constraining Stellar Evolution in Young Open Clusters with NGTS
Understanding stellar evolution is fundamental to astronomy, yet there remain significant gaps in our knowledge. Scientific progress requires testing our best explanations against observation, and open clusters act as key test sites for theories of stellar evolution. Observations of young open …
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Exoplanetary system WASP-3 : measurement of the projected spin-orbit angle and evidence for stellar activity
… angle between the planetary orbital axis and the stellar rotation axis, ... degrees. I use the new photometric data to refine the system parameters. Additionally, I present evidence for stellar activity, as the spectra obtained on UT June 19, 2008 reveal an increase in radial velocity to a peak …
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K-Star rapid rotators and the detection of relatively young multiple K-Star systems
… evidence of periodicities that indicate rapid stellar rotation. Many Kepler M, K, and G stars show modulations in flux due to rotating star spots, and these have been previously investigated by a number of different groups. Rotational periodicities mediated by the rotation of stellar spots were …
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Em busca de um novo indicador Espectroscópico do período de rotação das Estrelas do tipo solar
… with the dynamics of sunspots that the Sun has a rotation period of twenty-seven days around your axis. With the help of Project Sun-As-A-Star that solar spectra obtained for more than thirty years we observed oscillations of both the depth of the spectral line and its equivalent width, and …
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Motion of charged particles in pulsar magnetospheres
… view: (i) For the case of aligned magnetic and rotational axes we solve a fluid version of the Lorentz-Dirac equation, in the Landau approximation, for a two-component plasma. We start from an approximately force-free initial condition and numerically integrate the equations of motion for a time …
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Multi-dimensional simulations of bow shocks of massive, high-velocity runaway stars
Stellar bow shocks result from the supersonic collision of stellar winds ejected by runaway stars and the interstellar medium (ISM). Studying their properties provides constraints on mass-loss rates, stellar wind velocities and the properties of the ISM. In this work, we study the formation of bow …
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Ground-based transmission spectroscopy of three inflated Hot Jupiter exoplanets
… photometrically to correct for influences of stellar activity if necessary. The obtained measurements of the three objects all favor featureless spectra. A variety of atmospheric compositions can explain the lack of a wavelength dependent absorption. But the broad trend of featureless spectra …
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Variability of young solar-type stars : Spot cycles, rotation, and active longitudes
… fields. When these magnetic fields penetrate the stellar surface, they give rise to directly observable activity phenomena, such as dark spots and line emission from the chromospheric layers. Observing and analyzing these activity indicators allows us to characterize the behaviour of the dynamos …