A Diffuse Metal-poor Component of the Sagittarius Stream Revealed by the H3 Survey
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Author
Johnson, Benjamin D.
Conroy, Charlie
Naidu, Rohan P.
Bonaca, Ana
Zaritsky, Dennis
Ting, Yuan-Sen
Cargile, Phillip A.
Han, Jiwon Jesse
Speagle, Joshua S.
Affiliation
Univ Arizona, Steward ObservIssue Date
2020-09
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Johnson, B. D., Conroy, C., Naidu, R. P., Bonaca, A., Zaritsky, D., Ting, Y. S., ... & Speagle, J. S. (2020). A Diffuse Metal-Poor Component of the Sagittarius Stream Revealed by the H3 Survey. The Astrophysical Journal, 900(2), 103.Journal
ASTROPHYSICAL JOURNALRights
© 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
The tidal disruption of the Sagittarius dwarf galaxy has generated a spectacular stream of stars wrapping around the entire Galaxy. We use data from Gaia and the H3 Stellar Spectroscopic Survey to identify 823 high-quality Sagittarius members based on their angular momenta. The H3 Survey is largely unbiased in metallicity, and so our sample of Sagittarius members is similarly unbiased. Stream stars span a wide range in [Fe/H] from -0.2 to -3.0, with a mean overall metallicity of <[F/H]> = -0.99. We identify a strong metallicity dependence to the kinematics of the stream members. At [Fe/H] > -0.8 nearly all members belong to the well-known cold (sigma(v) < 20 km s(-1)) leading and trailing arms. At intermediate metallicities (-1.9 < [Fe/H] < -0.8) a significant population (24%) emerges of stars that are kinematically offset from the cold arms. These stars also appear to have hotter kinematics. At the lowest metallicities ([Fe/H] less than or similar to -2), the majority of stars (69%) belong to this kinematically offset diffuse population. Comparison to simulations suggests that the diffuse component was stripped from the Sagittarius progenitor at earlier epochs, and therefore resided at larger radius on average than the colder metal-rich component. We speculate that this kinematically diffuse, low-metallicity population is the stellar halo of the Sagittarius progenitor system.Note
Immediate accessISSN
0004-637XEISSN
1538-4357Version
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/abab08