2026-09-24T17:10:50Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/67510 2023-07-11 col_2142_5131 col_2142_14807 com_2142_5130 com_2142_14806 com_2142_8903

Hartkopf, William Irving 2014-12-14T05:15:30Z 2014-12-14T05:15:30Z 10000-01-01 1981 1981 DDO observations of 1076 G and K stars at the north and south galactic poles are combined with published photometry to give a new abundance gradient perpendicular to the galactic plane to z-distances greater than 5 kpc. Additional DDO photometry of bright field stars has been used to calibrate the DDO abundance index against {Fe/H} for metal-poor stars. The resulting gradient in {Fe/H} is about -0.33 kpc('-1) out to 2 kpc, decreasing to about -0.23 kpc('-1) for 2 < z < 5 kpc. The discrepancy between earlier results (utilizing only the DDO CN anomaly) and the present values is resolved. The distribution in metallicity found for K-giants above 1 kpc is consistent with Searle and Zinn's (1978 Astrophys. J. 225,357) idea that the halo formed by the merging of a number of star-forming regions or "fragments". Gas lost from these fragments condensed into the plane and provided material for enrichment of the disk. Radial velocities observed for 302 for our polar giants, coupled with published velocities, have enabled us to determine the z-component of the velocity dispersion to a height of over 4 kpc. In combination with the photometry, the radial velocities allow us to determine velocity dispersions as a function of abundance, as well. The abundances found for our high-z stars is similar to the A-star results of Rodgers (1971 Astrophys. J. 244,912), in that about half of the K-giants above 1 kpc have solar abundances. The kinematic differences between Rodgers' stars and ours are inconsistent with the idea of a common origin, however. Finally, we also calculate new values of the perpendicular acceleration function K(,z)(z) at high z-distances and investigate the sensitivity of K(,z) determinations to the density function used. The need for a new, more extensive D(z) determination is discussed. Made available in DSpace on 2014-12-14T05:15:30Z (GMT). No. of bitstreams: 1 8203484.pdf: 6920076 bytes, checksum: b013c9a5bdb1ca095bbadf28b3834c73 (MD5) Previous issue date: 1981 Embargo set by: Seth Robbins for item 67688 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 181 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981. http://hdl.handle.net/2142/67510 (UMI)AAI8203484 eng Physics, Astronomy and Astrophysics A Kinematic and Abundance Survey of the Galactic Pole Regions text Astronomy Astronomy University of Illinois at Urbana-Champaign Dissertation Ph.D.