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.
Results
Showing 1 to 17 of 17 for “"Stellar parameters"”.
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A pipeline for the analysis of stellar spectra
… are able to turn raw data files into tables of stellar parameters and chemical abundances in far less time than if they were analysed by hand. The results from these surveys open new windows on to the history of our galaxy and other disk galaxies. In this thesis, we present the development of a …
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Modelling interstellar extinction in stellar populations
In stellar astrophysics, the determination of the magnitude of interstellar extinction is critical, due to its effect on the observed brightness and colour of the stars. Extinction is therefore an important factor in deriving scientific information from the colour-magnitude diagrams (CMDs) of …
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Optical study of F, G and K stars in the ROSAT All-Sky Survey
… well as spectroscopic (high-resolution). Various parameters are determined for the sample objects, mainly spectral types and luminosity classes, absolute magnitudes, distances, radial velocities, projected rotational velocities, effective temperatures, Lithium abundances. I compare the X-ray …
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Chemical abundance analysis of HE 2324-0215, an r-process-enhanced metal-poor star
… elements and 14 light elements with Z < 30. The stellar parameters are [Fe/H] = -3.05 ± 0.17, Teff = 4477 K, Vt = 2.70 kms-1 , and log(g) = 0.70, indicating that HE 2324-0215 is a red giant star. The [Eu/Fe] = 0.73 and [Ba/Eu] = -0.68 suggests that this is an r-I star. Since thorium is detectable …
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Effects of starspots activity on optical and near infrared observations of planetary transits
… thesis, I report on the effects that magnetic stellar activity of solar-type stars induces on stellar light curves involved in the photometric technique for the detection and characterization of transiting extra-solar planets that is one of the most effective detection methods, the first being …
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Chemical and kinematic properties of bright metal poor stars
… the atmospheres of these stars by determing stellar parameters {Teff, log(g), [mu], [Fe/H]} and obtain also their chemical abundances for 17 elements including Fe, C, Sr, and Ba. Three of these stars are found to possess an overabundance of Carbon relative to Iron. Combining these chemical …
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Asteroseismology from the main sequence to giant stars
… of asteroseismology to probe the structure of stellar sources. By observing pulsational variability, a detailed description of the interior of stars, and the determination of stellar parameters can be obtained. An extensive sample of bright K and M class giant stars were surveyed to detect the …
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Massive stars in the Galactic Center Quintuplet cluster
… 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 (Okuda et al. 1987, 1989) and was observed for this project with …
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Chemical gradients in the Milky Way from unsupervised chemical abundances measurements of the RAVE spectroscopic data set
… measures their radial velocities, atmospheric parameters and chemical abundances. The project makes use of the UK Schmidt telescope at Australian Astronomical Observatory (AAO) in Siding Spring, Australia, equipped with the multiobject spectrograph 6dF. To date, RAVE collected and measured more …
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Seyfert and starburst activity in galaxies: Modeling and analysis
… local galaxy sample. We developed new tools for stellar population analysis in the infrared, using stellar absorption features. These tools are ideally suited for studies of dusty galaxies and obscured stars in the Milky Way. We used the CO band at 2.3μm to estimate the contribution from red …
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Heartbeat Stars and the Ringing of Tidal Pulsations
… area and temperature variations over the stellar surface. In the precise Kepler data, these changes cause a notable variation in the light curve in the form of a tidal pulse. In this work I present novel modelling tools produced specifically to model heartbeat stars. These include the …
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Planets around cool stars: a spectroscopic and photometric study of M dwarfs and their planets
… their intrinsic faintness and poorly established stellar parameters (radius, metallicity, etc.). For this dissertation I have worked to mitigate these problems with the goals of finding new transiting planets and establishing the role of stellar metallicity on the size and occurrence of transiting …
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Development and Testing of a New Method for Velocity-Selecting White Dwarfs from Gaia by Galactic Population
… as trigonometric parallaxes, fitting up to nine stellar parameters for a given target. White dwarfs provide a valuable target type, as they are long$-$lived and stable objects which remain from the earliest epochs of star formation in each Galactic population. Gaia astrometry provides us with …
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The behavior of hydrogen and helium at white dwarf photosphere conditions
… the age of the universe, to test current stellar evolutionary models, and to constrain the physics of Type Ia supernovae as well as dark energy. Accurate WD masses are needed for all of these applications. In this thesis, I review the weaknesses of the currently available WD mass …
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Analysis methods for gravitational wave from binary neutron star coalescences: investigation on the post-merger phase
… and at the same time to estimate combinations of stellar parameters, such as mass and radius of the two objects. With these motivations, my PhD thesis addressed the development of a new data analysis tool in order to investigate the GW signal emitted during the PM phase following a NS coalescence. …
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Testing stellar models with observations from AGB and post-AGB stars
… loss, convective mixing, and grain formation in stellar winds. From an observational point of view it is difficult to determine stellar parameters such as the initial mass and metallicity. This makes it hard to constrain theoretical models with observations. The objective of my Ph.D. thesis is to …
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Testing stellar models with observations from AGB and post-AGB stars
… loss, convective mixing, and grain formation in stellar winds. From an observational point of view it is difficult to determine stellar parameters such as the initial mass and metallicity. This makes it hard to constrain theoretical models with observations. The objective of my Ph.D. thesis is to …