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 20 of 76 for “"Emission line"”.
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Photometric monitoring of early type emission line stars
… infrared (JHKL MNQ) photometry of early type, emission line, stars is described. Particular emphasis is placed on observations of suspected pre-main-sequence objects such as Herbig Ae/Be stars. The observations, together with data from the IRAS point source catalogue, are analysed to probe the …
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High resolution studies of early type emission line stars
This thesis presents a study of early type, emission line objects on small angular scales. Spectroastrometry is used to separate the spectra of unresolved Herbig Ae/Be binary systems. The separated spectra allow the mass ratio of the systems to be established. The separation and mass ratio …
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The Nature of Emission-Line Galaxies in Hierarchical Cosmologies
… model to study the nature and evolution of emission line galaxies. In particular, we focus on the properties of Ly-alpha and H-alpha emitters, due to their many cosmological applications being considered for current and future observational studies. By combining a semianalytical model with a …
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Emission Line Galaxies from CADIS : High Redshift Lyman-Alpha Galaxies and Metal Poor Galaxies at Medium Redshift
… for and investigated in a sample of 600 faint emission line galaxies from four fields of the Calar Alto Deep Imaging Survey (CADIS). Employing an imaging Fabry-Perot interferometer, CADIS detects emission lines in three waveband windows, free of night-sky emission lines, at 700 nm, 820 nm, and …
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Optical remote sensing of thermospheric emission with the Sky-Calibrated Imaging Photometer
Optical remote sensing of emission lines is a well-established approach to estimating atmospheric parameters. The neutral oxygen 844.6 nm emission line has long been considered a good candidate for estimating the oxygen density in the upper thermosphere due to its brightness and relatively simple …
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The Physical Nature of The Symbiotic Stars
The physical nature of the peculiar emission-line objects known as symbiotic stars is examined. The available observations of these objects can be understood best if they are binaries consisting of a late-type giant and a hot component which ionizes a gaseous nebula.
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Differential polarization of Hβ in γ CAS
… 0.15 Å/pixel ) spectropolarimetry across the Hβ emission line of the Be star γ Cas is presented. The differential polarization and polarization angle vary both in profile and depth. It was found that the polarization profile fits the relation PL, = (Iunderlying / Itotal)Pc, instead of the …
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Orion B--Anatomy of a Star-Forming Region
… the VLA in the radio continuum and OH absorption line at a frequency of 1667 MHz, in the near-infrared continuum and H$\sb2$ emission line at a wavelength of 2 $\mu$m, and in several millimeter-wavelength molecular transitions (of HCO$\sp+$, SO, H$\sp $CN, and HC$\sp $N) with the Hat Creek Array.
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Reverberation mapping of Active Galactic Nuclei
… makes use of the time variability of the broad emission lines from the nearby broad-line region (BLR) to measure their time response or delay (τ) relative to the incident ionizing continuum from the accretion disc. This delay is a consequence of light-travel time effects and directly enables the …
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A technique for astronomical spectroscopy with a multi-aperture telescope
A technique for acquiring spectral line data using a multi-aperture telescope is described. The multi-aperture principle and the criteria which led to the selection of a dispersive spectrometer are discussed. The problem of linking telescope and spectrometer has been solved by incorporating low …
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The analysis of some bivariate astronomical time series
In the first part of the thesis, a linear time domain transfer function is fitted to satellite observations of a variable galaxy, NGC5548. The transfer functions relate an input series (ultraviolet continuum flux) to an output series (emission line flux). The methodology for fitting transfer …
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Luminescence in ZnO
… the next generation of optoelectronic , light emission or high power and high frequency devices. In order to make electrical device from ZnO, it is necessary to investigate optical properties of ZnO.In this thesis, PL setup and the properties of ZnO are introduced briefly and the optical …
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Excitation processes in the positive column of electrical discharges in inert gases
… current i, of the intensity, I, of neon spectral lines emitted from low pressure positive column discharges has been studied as part of an investigation of excitation processes in these discharges. The results indicate that two-step excitation is important for many neon lines. Measurements of …
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New results from the gravitational lensing of galaxies
… elliptical galaxies which are lensing background emission-line galaxies and have been observed by the SLACS collaboration using HST and SDSS to place constraints on the post-Newtonian parameter 7 and the cosmological parameter A. We find y = 1.00 ± 0.04 on kiloparsec scales, consistent with the …
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Exploring star formation in dwarf galaxies at Z1
… a sample derived from the Redshift One LDSS3 Emission Line Survey (ROLES), which used [OII]3727 as a tracer of star formation to target very low stellar masses (M~10 8:5M) at this epoch. In this dissertation, we study these low mass ROLES galaxies using near-infrared slitless spectroscopy from …
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Probing quasar sight lines in three dimensions
Strong damped Lyman alpha absorption (DLA) lines seen spectra of distant quasar are believed to arise when the sight line to the quasar goes trough the disc of a galaxy or a proto galaxy. Most of the neutral matter in the universe is contained in these clouds of neutral hydrogen that cause the …
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Quasars at the High Redshift Frontier
… Its spectrum shows a relatively weak Lyman-α emission line, which has been interpreted as evidence of absorption by neutral gas. Attributing this to a Gunn-Peterson damping wing has led to claims that the intergalactic medium is at least 10% neutral at that redshift. However, these claims rely …
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X-ray searches for decaying sterile neutrinos with the Micro-X and XQC sounding rockets
… A recent detection of an unidentified X-ray emission line has been suggested as a possible signal of sterile neutrino decay, but requires more observations with high-resolution spectroscopy to fully explore the nature of the line. In the first half of this thesis, we present the results from …
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Precision X-ray spectroscopy of 3C 273 jet knots
… Using these spectra we searched for narrow emission line candidates and, based on significance values calculated for the observed photon counts in each bin of the spectrum of the entire jet, we selected three possible emission candidates and attempted to match these with known highly …
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Investigating the role of ionised outflows in galactic evolution through spatially resolved spectroscopy
… By investigating the optical and near-IR emission line ratios of the outflowing gas, I unambiguously prove star formation is occurring within the gas. This is supported by the ionisation parameter of the gas, showing the gas excitation must come from UV radiation due to stars in the …
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