Elemental abundance measurements for lanthanum, europium, and iron are presented for 504 stars in the solar neighborhood. The bulk of the data are planet search spectra taken with HIRES on the Keck I telescope at R=50,000, but a subset of 45 kinematically selected stars were observed on the Harlan J. Smith Telescope at McDonald Observatory at R=60,000 and S/N=100 at the 3988 angstrom lanthanum line and S/N=250 around 5240 angstrom near the iron lines. Statistical analyses of stellar kinematics in the solar neighborhood reveal much kinematic substructure in the disk, though it is not readily apparent whether this substructure is extragalactic or dynamical in origin. Much of the substructure can be quickly identified as well known moving groups of stars such as the Hercules, Sirius, and Hyades stellar streams. Additionally, the subset of kinematically selected stars observed at McDonald Observatory are members of a stellar stream putatively identified by Amina Helmi as part of a merger remnant. Taking advantage of a large data set and a homogeneous spectral analysis, a Kolmogorov-Smirnov hypothesis test is applied to investigate the possibility that these kinematic structures are chemically distinct from the Galactic Disk. In all cases, the kinematic streams have chemistries roughly consistent with the Galactic disk trends, although the statistical analyses suggest some subtle variations. The accretion hypothesis is not completely ruled out for Helmi's stream, but the chemical variations are interpreted primarily in terms of dynamical effects.
|Advisor:||Carney, Bruce W.|
|Commitee:||Cecil, Gerald, Champagne, Arthur E., Heitsch, Fabian, Kannappan, Sheila|
|School:||The University of North Carolina at Chapel Hill|
|Department:||Physics & Astronomy|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 73/06, Dissertation Abstracts International|
|Keywords:||Chemical tagging, Disk, Elemental abundance, Kinematic substructures, Solar neighborhood, Stellar kinematics|
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