Chemical Abundances in the Leiptr Stellar Stream
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Date
2024-05
Authors
Atzberger, Kaia
Journal Title
Journal ISSN
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Publisher
The Ohio State University
Abstract
Stellar streams are useful probes of the Galactic acceleration field, the gradient of the gravitational potential, and the small-scale substructure of the dark matter halo which make them important structures in the study of galaxy formation. The Leiptr stellar stream is one group in a large population of recently discovered stars that was ripped from its original system by the Milky Way’s gravitational attractive force, an astronomical phenomenon called tidal disruption. Stream stars preserve the elemental composition of their stellar atmospheres throughout their lifetimes. Determining those abundances provides critical information about whether the stream’s progenitor best matches the observed properties of a dwarf galaxy or globular cluster. Although past studies have found that the population of streams where Leiptr was discovered most likely consists of inner-halo globular clusters, this paper seeks to use follow-up spectroscopy to confirm its nature. We analyzed the absorption of light detected by the Magellan Telescopes’ high-resolution double echelle spectrograph, MIKE, at Las Campanas Observatory in Chile for 5 stream stars in the metal-poor, 48°-long Leiptr stream. Using MOOG, a radiative transfer code for stellar abundances, we corrected spectral fits to properly trace the continuum of light detected, measured the equivalent widths of Fe I and Fe II peaks to balance the model stellar atmosphere, and calculated the abundances of multiple other elements. We were able to eliminate the possibility of Leiptr's progenitor being a Milky Way globular cluster but need more data to confirm if it is a dwarf galaxy or was accreted from one.
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Keywords
Galactic Archaeology, Stellar Stream, Spectroscopy, Dwarf Galaxy, Globular Cluster, Chemical Abundance