Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi
Name
2001.04653.pdf
Description
Accepted version
Size
1.22 MB
Format
Adobe PDF
Checksum (MD5)
515de60937e27f185f17bb1ddcc04cc6
Author(s)
Chaplin, William J.
Serenelli, Aldo M.
Miglio, Andrea
Morel, Thierry
Mackereth, J. Ted
Vincenzo, Fiorenzo
Kjeldsen, Hans
Basu, Sarbani
Ball, Warrick H.
Stokholm, Amalie
Date Issued
January 2020
Journal
Nature Astronomy
Publisher
Springer Science and Business Media LLC
Citation
Chaplin, William J. et al. "Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi." Nature Astronomy 4, 4 (January 2020): 382–389 © 2020 The Author(s)
Version
Author's final manuscript
Abstract
Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to date precisely the age at which any one merger occurred. Recent results have revealed a population of stars that were accreted via the collision of a dwarf galaxy, called Gaia–Enceladus1, leading to substantial pollution of the chemical and dynamical properties of the Milky Way. Here we identify the very bright, naked-eye star ν Indi as an indicator of the age of the early in situ population of the Galaxy. We combine asteroseismic, spectroscopic, astrometric and kinematic observations to show that this metal-poor, alpha-element-rich star was an indigenous member of the halo, and we measure its age to be 11.0 ± 0.7 (stat) ± 0.8 (sys) billion years. The star bears hallmarks consistent with having been kinematically heated by the Gaia–Enceladus collision. Its age implies that the earliest the merger could have begun was 11.6 and 13.2 billion years ago, at 68% and 95% confidence, respectively. Computations based on hierarchical cosmological models slightly reduce the above limits.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1038/s41550-019-0975-9
