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 “"late-type stars"”.
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Zeeman-Doppler Imaging of active late-type stars
Stellare Magnetfelder spielen eine wichtige Rolle bei der Entstehung und Entwicklung von Sternen. Leider entziehen sie sich aber, aufgrund ihrer großen Entfernung zur Erde, einer direkten Beobachtung. Dies gilt zumindest für derzeitige und in naher Zukunft zur Verfügung stehende Instrumente. Um …
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Spot activity of late-type stars : a study of II Pegasi and DI Piscium
All stars that have outer convection zones show magnetic activity. This activity strengthens with angular velocity and depth of the convection zone. Cool starspots are believed to be caused by local magnetic field concentrations on the surfaces of stars. They show up as dark regions against a …
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The chemistry of metal-containing molecules in the circumstellar envelopes of late-type stars: Millimeter-wave observations and abundance modeling
… of Asymptotic Giant Branch (AGB) and post-AGB stars has been conducted in order to investigate the role of metal-containing compounds in the circumstellar envelopes surrounding these objects. The role of metal bearing molecules in the chemical evolution of these envelopes was also examined. …
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Generation and propagation of longitudinal tube waves in late-type stellar atmospheres and the rotation-emission activity relation
… the turbulent medium of the convection zones of late-type stars were computed. Solar magnetic flux tubes of different filling factors were heated with adiabatic and radiatively damped LTW. It was found that the tube geometry plays an important role for heating the outer layers. The response of …
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Planets around cool stars: a spectroscopic and photometric study of M dwarfs and their planets
… searches. Smaller planets can be detected around stars with smaller radii (via the transit technique) or lower mass (via the radial velocity technique). Planets in the habitable zone of an M dwarf are closer in, and thus easier to detect, than those orbiting in the habitable zone of Solar-type …
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Massive stars in the Galactic Center Quintuplet cluster
… the spectral analysis of the cluster Wolf-Rayet stars of the nitrogen sequence to determine their fundamental stellar parameters, and discusses the obtained results in a general context. The Quintuplet cluster was discovered in one of the first infrared surveys of the Galactic center region …
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The Structure and Polarization Properties of the SiO Masers in the Extended Atmosphere of R Aquarii
… maser emission has been observed towards many late-type stars. The conditions necessary for the formation of SiO masers dictate that they be produced in a region which is inside the silicate dust formation point close to the surface of the star. Very Long Baseline Interferometry (VLBI) has …
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Chromospheric activity and lithium abundance in the NGC2516 and NGC3766 open clusters
… chromospheric activity and lithium abundance of late type stars in open clusters of different ages. The study of open cluster is very important for our understanding of stellar evolution and atmospheres, since all cluster members have almost the same age and chemical composition and this allows …
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Variability of young solar-type stars : Spot cycles, rotation, and active longitudes
The outer convective envelopes of late-type stars are believed to support turbulent dynamos that are able to generate strong and dynamic magnetic fields. When these magnetic fields penetrate the stellar surface, they give rise to directly observable activity phenomena, such as dark spots and line …