The GALAH survey: chemodynamics of the solar neighbourhood
Article
Article Title | The GALAH survey: chemodynamics of the solar neighbourhood |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Hayden, Michael R. (Author), Bland-Hawthorn, Joss (Author), Sharma, Sanjib (Author), Freeman, Ken (Author), Kos, Janez (Author), Buder, Sven (Author), Anguiano, Borja (Author), Asplund, Martin (Author), Chen, Boquan (Author), de Silva, Gayandhi M. (Author), Khanna, Shourya (Author), Lin, Jane (Author), Horner, Jonathan (Author), Martell, Sarah (Author), Ting, Yuan-Sen (Author), Wyse, Rosemary (Author), Zucker, Daniel (Author) and Zwitter, Tomaz (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 493 (2), pp. 2952-2964 |
Number of Pages | 13 |
Year | 2020 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/staa335 |
Web Address (URL) | https://academic.oup.com/mnras/article/493/2/2952/5733167 |
Abstract | We present the chemodynamic structure of the solar neighbourhood using 55 652 stars within a 500 pc volume around the Sun observed by GALAH and with astrometric parameters from Gaia DR2. We measure the velocity dispersion for all three components (vertical, radial, and tangential) and find that it varies smoothly with [Fe/H] and [α/Fe] for each component. The vertical component is especially clean, with σ _{v_z} increasing from a low of 10 km s<SUP>-1</SUP> at solar [α/Fe] and [Fe/H] to a high of more than 50 km s<SUP>-1</SUP> for more metal-poor and [α/Fe] enhanced populations. We find no evidence of a large decrease in the velocity dispersion of the highest [α/Fe] populations as claimed in surveys prior to Gaia DR2. The eccentricity distribution for local stars varies most strongly as a function of [α/Fe], where stars with [α/Fe] < 0.1 dex having generally circular orbits (e < 0.15), while the median eccentricity increases rapidly for more [α/Fe] enhanced stellar populations up to e ∼ 0.35. These [α/Fe] enhanced populations have guiding radii consistent with origins in the inner Galaxy. Of the stars with metallicities much higher than the local interstellar medium ([Fe/H] > 0.1 dex), we find that the majority have e < 0.2 and are likely observed in the solar neighbourhood through churning/migration rather than blurring effects, as the epicyclic motion for these stars is not large enough to reach the radii at which they were likely born based on their metallicity. |
Keywords | Galaxy: abundances; Galaxy: kinematics and dynamics; Galaxy: stellar; content; Galaxy: structure; Astrophysics - Astrophysics of Galaxies |
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 ©: 2020 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 Virginia, United States | |
Centre for Astrophysics | |
University of New South Wales | |
Institute for Advanced Study, United States | |
Johns Hopkins University, United States | |
Macquarie University | |
University of Ljubljana, Slovenia |
https://research.usq.edu.au/item/q5x0y/the-galah-survey-chemodynamics-of-the-solar-neighbourhood
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