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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.
161

Radial velocity measurements of late-type stars

Lindgren, Harri. January 1994 (has links)
Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted. Includes bibliographical references (p. 52-63).
162

The spectral classification of M-dwarf stars

Boeshaar, Patricia C. January 1976 (has links)
Thesis (Ph. D.)--Ohio State University, 1976. / Includes vita. Includes bibliographical references (leaves 74-78).
163

Emission line relative intensity variations in the symbiotic stars CI Cygni, BF Cygni, AX Persei and V1016 Cygni /

Oliversen, Nancy Ann, January 1982 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
164

Abundance analyses of late-type dwarfs

Hartmann, Lee, January 1976 (has links)
Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 118-119).
165

The structure of the Coma cluster of galaxies

Noonan, Thomas Wyatt. January 1961 (has links)
Thesis (Ph. D.)--California Institute of Technology, 1961. / Photocopy of typescript. Includes bibliographical references (leaves 77-78).
166

Die neuen sterne ...

Tuchenhagen, Siegmar. January 1938 (has links)
Inaug.-diss.--Berlin.
167

Evolution of low-mass protostars /

Young, Chadwick Hayward. January 2005 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references (leaves 192-201). Also available in an electronic version.
168

Star formation in Camelopardalis: Cam OB1

Lyder, David Anthony 25 July 2018 (has links)
Star formation in the Cam OB1 region is investigated. Star formation, in general, is considered in terms of three elements: a) the structural relationship between the parent molecular clouds and newly formed stars, b) the temporal evolution of the parent molecular clouds, and c) the probability of the occurrence of star formation. Star formation in Cam OB1 over the range in l and b considered in this work, is concentrated in the vicinity of Cam R1 and appears to have led to the formation of three distinct stellar groups: a) Group I. formed ~ 1 - 50 x 106 yr ago, and located spatially and kinematically between two CO complexes, b) Group II. formed ~ 1 - 3 x 106 yr ago. and coincident with one of the previously mentioned complexes, and c) Group III. the youngest group, formed ~ I - 20 x 104 yr ago, and located at the current point of intersection between the two complexes in (a). The mass function (MF) for Groups I and II is similar to the cloud mass function of the parent molecular clouds, i.e. a power-law with exponent α ~ 2. A similar analysis for the Group III stars and associated molecular clouds cannot be performed due to the relatively small numbers in both samples. The star forming efficiency (SFE) in all cases is ~ 1%. It is proposed that cloud-cloud collisions between the CO complexes in the region triggered the formation of Groups I and III, while Group II was produced by a shock induced by the radiation pressure and stellar winds from the stars in Group I. An analysis of the molecular cloud structure in Cam OB1 and the background Perseus arm also shows that the clouds in both regions are turbulent, and typical of clouds seen elsewhere in the Galaxy. However, the clouds in Cam OB1 show a large dispersion in the degree with which they are self-gravitating, with the larger, warmer clouds being gravitationally bound. The principal data set for this work comprises fully sampled [special characters omitted] observations of the western half of Cam OB1, which were obtained at the Center for Astrophysics during the winter of 1992-1993. These data have an effective resolution of 10', a velocity resolution of 0.65 km s-1, and a sensitivity of 0.115 K. High resolution (20") observations of the [special characters omitted] transition of the most active star forming region were obtained with the James Clerk Maxwell Telescope during the winter of 1994-1995. These observations led to the discovery of a second outflow. AFGL 490 – iki, associated with IRAS 03234+5843, in the immediate vicinity of the very well-studied molecular outflow AFGL 490. Additional observations of the [special characters omitted], taken with the 26m telescope at the Dominion Radio Astrophysical Observatory during the fall of 1994, did not reveal any such masering activity in the Cam OB1 region, but did lead to the discovery of a new maser, associated with IRAS 02455+6034. in the background Perseus arm. / Graduate
169

12C/13C isotopic ratios in red-giant stars of the open cluster NGC 6791

Szigeti, László, Mészáros, Szabolcs, Smith, Verne V, Cunha, Katia, Lagarde, Nadège, Charbonnel, Corinne, García-Hernández, D A, Shetrone, Matthew, Pinsonneault, Marc, Allende Prieto, Carlos, Fernández-Trincado, J G, Kovács, József, Villanova, Sandro 03 1900 (has links)
Carbon isotope ratios, along with carbon and nitrogen abundances, are derived in a sample of 11 red-giant members of one of the most metal-rich clusters in the Milky Way, NGC 6791. The selected red-giants have a mean metallicity and standard deviation of [Fe/H] = +0.39 +/- 0.06 (Cunha et al. 2015). We used high-resolution H-band spectra obtained by the SDSS-IV Apache Point Observatory Galactic Evolution Experiment. The advantage of using high-resolution spectra in the H band is that lines of CO are well represented and their line profiles are sensitive to the variation of C-12/C-13. Values of the C-12/C-13 ratio were obtained from a spectrum synthesis analysis. The derived C-12/C-13 ratios varied between 6.3 and 10.6 in NGC 6791, in agreement with the final isotopic ratios from thermohaline-induced mixing models. The ratios derived here are combined with those obtained for more metal poor red-giants from the literature to examine the correlation between C-12/C-13, mass, metallicity, and evolutionary status.
170

Adding the s-Process Element Cerium to the APOGEE Survey: Identification and Characterization of Ce ii Lines in the H-band Spectral Window

Cunha, Katia, Smith, Verne V., Hasselquist, Sten, Souto, Diogo, Shetrone, Matthew D., Allende Prieto, Carlos, Bizyaev, Dmitry, Frinchaboy, Peter, García-Hernández, D. Anibal, Holtzman, Jon, Johnson, Jennifer A., Jőnsson, Henrik, Majewski, Steven R., Mészáros, Szabolcs, Nidever, David, Pinsonneault, Mark, Schiavon, Ricardo P., Sobeck, Jennifer, Skrutskie, Michael F., Zamora, Olga, Zasowski, Gail, Fernández-Trincado, J. G. 01 August 2017 (has links)
Nine Ce II lines have been identified and characterized within the spectral window observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey (between lambda 1.51 and 1.69 mu m). At solar metallicities, cerium is an element that is produced predominantly as a result of the slow capture of neutrons (the s-process) during asymptotic giant branch stellar evolution. The Ce II lines were identified using a combination of a high-resolution (R = lambda/delta lambda = 100,000) Fourier Transform Spectrometer (FTS) spectrum of a Boo and an APOGEE spectrum (R. =. 22,400) of a metal-poor, but s-process enriched, red giant (2M16011638-1201525). Laboratory oscillator strengths are not available for these lines. Astrophysical gf-values were derived using alpha Boo as a standard star, with the absolute cerium abundance in alpha Boo set by using optical Ce II lines that have precise published laboratory gf-values. The near-infrared Ce II lines identified here are also analyzed, as consistency checks, in a small number of bright red giants using archival FTS spectra, as well as a small sample of APOGEE red giants, including two members of the open cluster NGC 6819, two field stars, and seven metal-poor N-and Al-rich stars. The conclusion is that this set of Ce II lines can be detected and analyzed in a large fraction of the APOGEE red giant sample and will be useful for probing chemical evolution of the s-process products in various populations of the Milky Way.

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