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Showing 1 to 20 of 44 for “"white dwarfs"”.
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Topics in White Dwarfs
The observations of the 12 known magnetic white dwarfs are reviewed and a list of mechanisms is discussed which could give rise to the observed absorption and polarization spectra. Particular emphasis is placed on the observations of, and mechanisms important in the 3 magnetic white dwarfs to be …
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White Dwarfs and Neutron Stars
Submitted by Jesse Garrison (jagarris@illinois.edu) on 2011-07-06T20:18:48Z No. of bitstreams: 1 1972_sutherland.pdf: 5521266 bytes, checksum: edbe7909c32b744c3af18c47a5e720c8 (MD5)
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Nonlinear behaviour of pulsating white dwarfs
… nonlinear properties of the pulsations of two white dwarfs, namely DA G29-38 and DB GD358. The data at my disposal comprised numerous single- and multi-sites time series photometric campaigns, including light curves from four Whole Earth Telescope runs conducted respectively in 1988 and 1992 on …
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Exogeology as Revealed by Polluted White Dwarfs
… of information in the form of dead stars called white dwarfs. Many white dwarfs have accreted remnants of their own planetary systems, causing their atmospheres to become polluted by heavy elements. The relative quantities of these elements contain a wealth of information about the composition of …
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Theoretical studies of nuclear burning on white dwarfs
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.
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Cool white dwarfs and the age of the galaxy
White dwarf stars represent the most common endpoint of stellar evolution and therefore provide a reliable estimate of the star formation history and age of different Galactic populations. The major observational requirement for accurate age measurements is to have a large sample of cool, old white …
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Polluted White Dwarfs: Insights into Ancient Extrasolar Planetary Systems
… this thesis, I demonstrate how the pollution of white dwarf stars by rocky exoplanetary material offers an insight into the bulk composition of rocky exo-planets, and thus, the geological processes which occur on them. I present a model which reproduces the atmospheric metal abundances present in …
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The broad spectral energy distributions of accreting white dwarfs
Cataclysmic Variable stars (CVs) are excellent examples of multi-wavelength objects. They have been detected at all frequencies, from radio to γ-ray. However, while large sets of multi-wavelength data exist, few studies have been performed on the broad spectral energy distributions (SEDs) of these …
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Strong Magnetic Field Effects and Molecular Processes with Applications to White Dwarfs
… fields of strength applicable to magnetic white dwarfs, i.e. B < 10<sup>3</sup> megagauss, have been investigated for field-free principal quantum numbers n < 6. Finite proton mass corrections are included. Relativistic corrections are also investigated. Transition probabilities are …
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Dust disks around hot white dwarfs and central stars of planetary nebulae
… types of dust disks have been discovered around white dwarfs (WDs): small dust disks within the Roche limits of their WDs, and a large dust disk around the hot central WD of the Helix planetary nebula (PN), possibly produced by collisions among Kuiper Belt-like objects.To search for more dust …
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Last Call for Life: Habitability of Terrestrial Planets Orbiting Red Giants and White Dwarfs
… the star becomes a red giant, and then later a white dwarf. To search planets in these systems for signs of life it is essential that we understand how stellar evolution influences atmospheric photochemistry along with detectable biosignatures. We use EXO-Prime, which consists of a 1D coupled …
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Physics in the extreme: X-ray and optical studies of magnetic white dwarfs and related objects
… a high inclination and harbour weakly magnetic white dwarfs with spin periods 17-22 min. There is also a strong focus on studying the long term behaviour in intermediate polars in this thesis. Chapter 5 presents results from Kepler observations of FO Aquarii taken over 69 consecutive days. The …
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Development and Testing of a New Method for Velocity-Selecting White Dwarfs from Gaia by Galactic Population
… velocity-selecting targets from a sample of white dwarfs from the Gaia DR3 catalog that have also been age-analysed using BASE-9. BASE-9 uses photometry, as well as prior measurements and values from ancillary data, such as trigonometric parallaxes, fitting up to nine stellar parameters for a …
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The binary system containing the pulsar PSR 1913+16 and ultra-violet and x-radiation from accreting magnetic white dwarfs
… the companion be a black hole, a neutron star, a white dwarf or a helium main-sequence star. Observable second-order relativistic effects mayor may not further restrict the list of candidates. The discussion summarjzes Masters and Roberts, 1975 Ap. J. (Letters), l.25.., L 107, and Roberts t …
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Observational Insights into White Dwarf Planetary Systems
… their characterisation. Spectroscopic studies of white dwarfs ‘polluted’ by planetary material are a unique laboratory allowing measurements of their bulk composition. This thesis focuses on these polluted white dwarfs to observationally investigate how the material ultimately accretes onto the …
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Theoretical statistics of zero-age cataclysmic variables
"The distribution of the white dwarf masses, the distribution of the mass ratios and the distribution of the orbital periods in cataclysmic variables which are forming at the present time are calculated. These systems are referred to as ""zero-age cataclysmic variables"". The results show that 60% …
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Characterization of the Galactic White Dwarf Population in the Next Generation Virgo Cluster Survey
Halo white dwarfs remain one of the least studied stellar populations in the Milky Way because of their faint luminosities. Recent work has uncovered a population of hot white dwarfs which are thought to be remnants of low-mass Population II stars. This thesis uses optical data from the Next …
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Pulsations in the white dwarf primary of a cataclysmic variable star
… powerful techniques for the study of pulsating white dwarf stars. If these techniques could be applied to the white dwarf primaries of Cataclysmic Variable stars, the study of accretion in interacting binary systems would benefit enormously. Our understanding of normal modes in white dwarf …
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Star Formation History of the Milky Way Galaxy Disk Using a Hierarchical Model
… the Galactic population is to learn about the white dwarfs (WDs) from that particular Galactic population. Understanding the white dwarfs can tell us a lot about the Galaxy's history. White dwarfs are the remnants of stellar evolution, providing an age dating method for various Galactic …
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