The GALAH survey: co-orbiting stars and chemical tagging

Simpson, Jeffrey D. and Martell, Sarah L. and Da Costa, Gary and Casey, Andrew R. and Freeman, Ken C. and Horner, Jonathan and Ting, Yuan-Sen and Nataf, David M. and Lewis, Geraint F. and Ness, Melissa K. and Zucker, Daniel B. and Cottrell, Peter L. and Cotar, Klemen and Asplund, Martin and Bland-Hawthorn, Joss and Buder, Sven and D'Orazi, Valentina and de Silva, Gayandhi M. and Duong, Ly and Kos, Janez and Lin, Jane and Lind, Karin and Schlesinger, Katharine J. and Sharma, Sanjib and Zwitter, Tomaz and Kafle, Prajwal R. and Nordlander, Thomas (2019) The GALAH survey: co-orbiting stars and chemical tagging. Monthly Notices of the Royal Astronomical Society, 482 (4). pp. 5302-5315. ISSN 0035-8711

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We present a study using the second data release of the GALAH survey of stellar parameters and elemental abundances of 15 pairs of stars identified by Oh et al 2017. They identified these pairs as potentially co-moving pairs using proper motions and parallaxes from Gaia DR1. We find that 11 very wide (>1.7 pc) pairs of stars do in fact have similar Galactic orbits, while a further four claimed co-moving pairs are not truly co-orbiting. Eight of the 11 co-orbiting pairs have reliable stellar parameters and abundances, and we find that three of those are quite similar in their abundance patterns, while five have significant [Fe/H] differences. For the latter, this indicates that they could be co-orbiting because of the general dynamical coldness of the thin disc, or perhaps resonances induced by the Galaxy, rather than a shared formation site. Stars such as these, wide binaries, debris of past star formation episodes, and coincidental co-orbiters, are crucial for exploring the limits of chemical tagging in the Milky Way.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 25 Feb 2019 01:43
Last Modified: 13 Mar 2019 03:05
Uncontrolled Keywords: astrophysics; astrophysics of galaxies; solar astrophysics; stellar astrophysics
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Identification Number or DOI: 10.1093/mnras/sty3042

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