Chaplin, WJ, Serenelli, AM, Miglio, A, Morel, T, Mackereth, JT, Vincenzo, F, Basu, HKS, Ball, WH, Stokholm, A, Verma, K, Mosumgaard, JR, Aguirre, VS, Mazumdar, A, Ranadive, P, Antia, HM, Lebreton, Y, Ong, J, Appourchaux, T, Bedding, TR, Christensen-Dalsgaard, J, Creevey, O, García, RA, Handberg, R, Huber, D, Kawaler, SD, Lund, MN, Metcalfe, TS, Stassun, KG, Bazot, M, Beck, P, Bell, KJ, Bergemann, M, Buzasi, DL, Benomar, O, Bossini, D, Bugnet, L, Campante, TL, Orhan, ZÇ, Corsaro, E, González-Cuesta, L, Davies, GR, Mauro, MPD, Egeland, R, Elsworth, YP, Gaulme, P, Ghasemi, H, Guo, Z, Hall, OJ, Hasanzadeh, A, Hekker, S, Howe, R, Jenkins, JM, Jiménez, A, Kiefer, R, Kuszlewicz, JS, Kallinger, T, Latham, DW, Lundkvist, MS, Mathur, S, Montalbán, J, Mosser, B, Bedón, AM, Nielsen, MB, Örtel, S, Rendle, BM, Ricker, GR, Rodrigues, TS, Roxburgh, IW, Safari, H, Schofield, M, Seager, S, Smalley, B, Stello, D, Szabó, R, Tayar, J, Themeßl, N, Thomas, AEL, Vanderspek, RK, Rossem, WEV, Vrard, M, Weiss, A, White, TR, Winn, JN and Yıldız, M (2020) Age dating of an early Milky Way merger via asteroseismology of the naked-eye star $ν$ Indi. Nature Astronomy. ISSN 2397-3366

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Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies. While these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to precisely date 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 \textit{Gaia}-Enceladus, leading to a substantial pollution of the chemical and dynamical properties of the Milky Way. Here, we identify the very bright, naked-eye star $\nu$\,Indi as a probe 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 $11.0 \pm 0.7$ (stat) $\pm 0.8$ (sys)$\,\rm Gyr$. The star bears hallmarks consistent with it having been kinematically heated by the \textit{Gaia}-Enceladus collision. Its age implies that the earliest the merger could have begun was 11.6 and 13.2 Gyr ago at 68 and 95% confidence, respectively. Input from computations based on hierarchical cosmological models tightens (i.e. reduces) slightly the above limits.

Item Type: Article
Additional Information: The final accepted article can be found at;
Uncontrolled Keywords: age dating, milky way, asteroseismology
Subjects: Q Science > Q Science (General)
Q Science > QB Astronomy
Q Science > QB Astronomy > QB460 Astrophysics
Q Science > QB Astronomy > QB600 Planets. Planetology
Q Science > QB Astronomy > QB799 Stars
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 28 Jan 2020 09:58
Last Modified: 13 Jul 2020 01:30

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