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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

High spatial/spectral resolution X-ray observations and volumetric 3D modeling of superheated plasma in the planetary nebula BD+30°3639 /

Yu, Young Sam. January 2009 (has links)
Thesis (Ph.D)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (p. 201-206).

A multicomponent echelle spectral data analysis of four planetary nebulae

Armour, Mary-Helen. January 2000 (has links)
Thesis (M. Sc.)--York University, 2000. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 119-121). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ56161.


Reitmeyer, William Lawrence, 1923- January 1965 (has links)
No description available.


Zellner, Benjamin Holmes, 1942- January 1970 (has links)
No description available.

The Balmer decrement in the emission spectra of astronomical objects

Bloom, Gary Stuart, 1940- January 1969 (has links)
No description available.

The development and early application of the velocity-distance relation

Hetherington, Norriss S., January 1970 (has links)
Thesis--Indiana University. / Vita. Includes bibliographical references.

Far-infrared spectrophotometry of oxygen-rich and S-type stars /

Glaccum, William Joseph. January 1999 (has links)
Thesis (Ph. D.)--University of Chicago, Dept. of Astronomy and Astrophysics, August 1999. / Includes bibliographical references. Also available on the Internet.

The kinematics of selected planetary nebulae

Szyszka, Cezary Tadeusz January 2012 (has links)
Planetary nebulae are formed from the ejecta of evolved stars. These ejecta are swept up by the fast low density wind from the hot central star, as it evolves towards a white dwarf. The sweep-up mechanism is called the Interacting Stellar Winds model (Kwok et al. 1978). The history of mass loss is imprinted on the nebular ejecta. The velocity field of the ejecta traces the mass loss event. A continuous mass loss gives a different velocity field from a brief mass loss event. We employed Integral Field Unit spectroscopy to study the velocity fields of three Bulge Planetary Nebulae. The preliminary results show the advantage of continuously sampled IFU spectroscopy over long slit spectroscopy. The kinematic of the nebula NGC 6302 was studied in the plane of the sky by com- parison of two epochs of Hubble Space Telescope images separated by 10 years. A two dimensional velocity field was created from 200 measurements. The nebular lobes are found to follow a Hubble-Flow, and were ejected in a brief event 2250 ± 35 yr ago. The ejection of lobes occurred about 700 yr after the end of AGB mass loss. The distribution of ages revealed that the inner nebula appears to be younger. This effect can be explained with additional acceleration at later stages of nebula evolution. The central star of NGC 6302 is believed to be extremely hot based on observed ionization stages in the spectrum. In this thesis the detection of the NGC 6302 central star is reported. The luminosity of the star was determined to be 4 010 L⊙. Together with age of the nebula age the mass of the star could be considerably narrowed down the mass determination of the star to 0.64 ± 0.01 M⊙.

Radio observation of the Gum Nebula Region

Woermann, Beate January 1997 (has links)
This thesis describes the results of an investigation of the physical properties of the Gum Nebula. For this investigation a radio continuum map of the region was made at 2326 MHz and resolution ⅓° with the HartRAO antenna. This map was used to generate spectral index images and an infrared to radio flux density ratio (IRR) image. The latter image shows that the IRR of the nebula is in the range 20 to 250, identifying it as an old SNR. Several spectral index images of this region were generated using two different methods, one based on the isolation of the nebula from its background radiation, the other based on TT-plots (Turtle et al., 1962). The two methods yield similar results, which show that the nebula has a thermal shell with a non-thermal region in its interior. Below the galactic plane the thermal region dominates and above the plane the nonthermal region. These results suggest a model of an old SNR with an H II region shell. Spectral line observations of hydrogen recombination lines and hydroxyl (OH) were made with the HartRAO and the Mopra telescopes. The detection of hydrogen recombination lines at four positions in the thermal regions of the nebula give electron temperatures and emission measures in the ranges 4000 to 6000 K and 220 to 460 pc.cm⁻⁶ respectively. The turbulent velocities are of the order of 20 km/s. A search for shocked OH lines at 1667 MHz and 1720 MHz in the Gum Nebula gave results that were negative, but numerous unshocked 1667 MHz OH lines were detected. The latter were used in a test for an expansion of the nebula. The most plausible fit to the data gives an expansion centre at l = 260.5°, b = -2.5° and at a distance of 0.7 kpc from us. The front face angular radius and expansion velocity are 10.5° and 16 km/s respectively. The back face angular radius and expansion velocity are 8.50 and 7 km/s respectively.

Aspects of planetary formation.

Weidenschilling, Stuart John January 1976 (has links)
Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 99-104. / Ph.D.

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