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Showing 1 to 6 of 6 for “"Roap"”.
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Atmospheric temperature structure in the RoAp stars
The rapidly oscillating Ap (roAp) stars are a sub-group of the chemically peculiar stars of class 2 (CP2), which are characterised by peculiar spectra and anomalously strong lines of Sr, Cr, Eu and other rare earth elements. They have strong global dipole magnetic fields with effective strengths of …
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Studies of non-adiabatic pulsations in the atmospheres of the roAp stars
The roAp stars are high overtone pulsators characterised by strong global magnetic fields with effective field strength of between a few hundred to a few thousand Gauss. They also show overabundances in rare-earths and iron peak element. Multi-colour photometry of roAp stars shows that their …
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The Cape rapidly oscillating Ap star survey
… started with the intention of discovering more roAp stars suitable for asteroseismological studies and also to identify the limits of the roAp phenomenon in temperature and luminosity. This is the most extensive survey of the roAp phenomenon to date. Prior to the start of the Cape Survey, only …
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A spectroscopic study of the rapidly oscillating peculiar A star HD 134214
… typical of rapidly-oscillating Ap stars (roAp stars) using the 0.75-rn telescope at the South African Astronomical Observatory. Although a promising candidate pulsator was found in HD 156869, no such oscillations were seen in these stars. Further spectroscopic observations did discover a …
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Étude des étoiles chimiquement particulières observées avec TESS
… particulières (mCP) et à oscillations rapides (roAp) observées par TESS. La présence d'un champ magnétique stellaire peut conduire à la stratification des éléments chimiques dans l'atmosphère stellaire et entraîner l'apparition de taches de surabondance sur la surface stellaire qui provoquent …
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Population and community responses to anthropogenic environmental changes
… tool (Rank Occupancy-Abundance Profiles; ROAPs) to explore the effects anthropogenic changes have on plant communities and bird populations. Chapter one investigates the influence of nutrient deposition on native prairie grass communities. I show that soil phosphorus levels alter plant …