The GALAH survey: chemical tagging of star clusters and new members in the Pleiades
Article
Article Title | The GALAH survey: chemical tagging of star clusters and new members in the Pleiades |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Kos, Janez (Author), Bland-Hawthorn, Joss (Author), Freeman, Ken (Author), Buder, Sven (Author), Traven, Gregor (Author), de Silva, Gayandhi M. (Author), Sharma, Sanjib (Author), Asplund, Martin (Author), Duong, Ly (Author), Lin, Jane (Author), Lind, Karin (Author), Martell, Sarah (Author), Simpson, Jeffrey D. (Author), Stello, Dennis (Author), Zucker, Daniel B. (Author), Zwitter, Tomaz (Author), Anguiano, Borja (Author), Da Costa, Gary (Author), D'Orazi, Valentina (Author), Horner, Jonathan (Author), Kafle, Prajwal R. (Author), Lewis, Geraint (Author), Munari, Ulisse (Author), Nataf, David M. (Author), Ness, Melissa (Author), Reid, Warren (Author), Schlesinger, Katie (Author), Ting, Yuan-Sen (Author) and Wyse, Rosemary (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 473 (4), pp. 4612-4633 |
Number of Pages | 22 |
Year | 2018 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stx2637 |
Web Address (URL) | https://academic.oup.com/mnras/article/473/4/4612/4555384 |
Abstract | The technique of chemical tagging uses the elemental abundances of stellar atmospheres to 'reconstruct' chemically homogeneous star clusters that have long since dispersed. The GALAH spectroscopic survey - which aims to observe one million stars using the Anglo-Australian Telescope - allows us to measure up to 30 elements or dimensions in the stellar chemical abundance space, many of which are not independent. How to find clustering reliably in a noisy high-dimensional space is a difficult problem that remains largely unsolved. Here, we explore t-distributed stochastic neighbour embedding (t-SNE) - which identifies an optimal mapping of a high-dimensional space into fewer dimensions - whilst conserving the original clustering information. Typically, the projection is made to a 2D space to aid recognition of clusters by eye. We show that this method is a reliable tool for chemical tagging because it can: (i) resolve clustering in chemical space alone, (ii) recover known open and globular clusters with high efficiency and low contamination, and (iii) relate field stars to known clusters. t-SNE also provides a useful visualization of a high-dimensional space. We demonstrate the method on a data set of 13 abundances measured in the spectra of 187 000 stars by the GALAH survey. We recover seven of the nine observed clusters (six globular and three open clusters) in chemical space with minimal contamination from field stars and low numbers of outliers. With chemical tagging, we also identify two Pleiades supercluster members (which we confirm kinematically), one as far as 6 degrees-one tidal radius away from the cluster centre. |
Keywords | solar neighbourhood; red giants; elemental abundance; mass function; rave stars; campaign 1; classification; homogeneity; evolution; risk; open clusters; Pleiades |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Institution of Origin | University of Southern Queensland |
Byline Affiliations | University of Sydney |
Australian National University | |
Max Planck Society, Germany | |
University of Ljubljana, Slovenia | |
University of New South Wales | |
Macquarie University | |
University of Virginia, United States | |
National Institute for Astrophysics, Italy | |
Computational Engineering and Science Research Centre | |
University of Western Australia | |
INAF - Astronomical Observatory of Padova, Italy | |
Johns Hopkins University, United States |
https://research.usq.edu.au/item/q4xyq/the-galah-survey-chemical-tagging-of-star-clusters-and-new-members-in-the-pleiades
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