The GALAH survey: no chemical evidence of an extragalactic origin for the Nyx stream

Zucker, Daniel B. and Simpson, Jeffrey D. and Martell, Sarah L. and Lewis, Geraint F. and Casey, Andrew R. and Ting, Yuan-Sen and Horner, Jonathan and Nordlander, Thomas and Wyse, Rosemary F. G. and Zwitter, Tomaz and Bland-Hawthorn, Joss and Buder, Sven and Asplund, Martin and de Silva, Gayandhi M. and D'Orazi, Valentina and Freeman, Ken C. and Hayden, Michael R. and Kos, Janez and Lin, Jane and Lind, Karin and Schlesinger, Katharine J. and Sharma, Sanjib and Stello, Dennis (2021) The GALAH survey: no chemical evidence of an extragalactic origin for the Nyx stream. The Astrophysical Journal Letters, 912 (2):L30. pp. 1-7. ISSN 2041-8205

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Abstract

The results from the ESA Gaia astrometric mission and deep photometric surveys have revolutionized our knowledge of the Milky Way. There are many ongoing efforts to search these data for stellar substructure to find evidence of individual accretion events that built up the Milky Way and its halo. One of these newly identified features, called Nyx, was announced as an accreted stellar stream traveling in the plane of the disk. Using a combination of elemental abundances and stellar parameters from the GALAH and Apache Point Observatory Galactic Evolution Experiment (APOGEE) surveys, we find that the abundances of the highest likelihood Nyx members are entirely consistent with membership of the thick disk, and inconsistent with a dwarf galaxy origin. We conclude that the postulated Nyx stream is most probably a high-velocity component of the Milky Way's thick disk. With the growing availability of large data sets including kinematics, stellar parameters, and detailed abundances, the probability of detecting chance associations increases, and hence new searches for substructure require confirmation across as many data dimensions as possible.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Accepted version embargoed until 10 May 2022 (12 months), in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 26 Jul 2021 06:39
Last Modified: 28 Jul 2021 04:22
Uncontrolled Keywords: Milky Way disk; Milky Way dynamics; galactic abundances; stellar; abundances; stellar streams; galaxy structure; 1050; 1051; 2002; 1577; 2166; 622; astrophysics; astrophysics of galaxies
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/2041-8213/abf7cd
URI: http://eprints.usq.edu.au/id/eprint/42822

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