article published yes William J. Chaplin author Aldo M. Serenelli author Andrea Miglio author Thierry Morel author J. Ted Mackereth author Fiorenzo Vincenzo author Hans Kjeldsen author Sarbani Basu author Warrick H. Ball author Amalie Stokholm author Kuldeep Verma author Jakob Rørsted Mosumgaard author Victor Silva Aguirre author Anwesh Mazumdar author Pritesh Ranadive author H. M. Antia author Yveline Lebreton author Joel Ong author Thierry Appourchaux author Timothy R. Bedding author Jørgen Christensen-Dalsgaard author Orlagh Creevey author Rafael A. García author Rasmus Handberg author Daniel Huber author Steven D. Kawaler author Mikkel N. Lund author Travis S. Metcalfe author Keivan G. Stassun author Michäel Bazot author Paul G. Beck author Keaton J. Bell author Maria Bergemann author Derek L. Buzasi author Othman Benomar author Diego Bossini author Lisa Annabelle Bugnet author d9edb345-f866-11ec-9b37-d119b52345010000-0003-0142-4000 Tiago L. Campante author Zeynep Çelik Orhan author Enrico Corsaro author Lucía González-Cuesta author Guy R. Davies author Maria Pia Di Mauro author Ricky Egeland author Yvonne P. Elsworth author Patrick Gaulme author Hamed Ghasemi author Zhao Guo author Oliver J. Hall author Amir Hasanzadeh author Saskia Hekker author Rachel Howe author Jon M. Jenkins author Antonio Jiménez author René Kiefer author James S. Kuszlewicz author Thomas Kallinger author David W. Latham author Mia S. Lundkvist author Savita Mathur author Josefina Montalbán author Benoit Mosser author Andres Moya Bedón author Martin Bo Nielsen author Sibel Örtel author Ben M. Rendle author George R. Ricker author Thaíse S. Rodrigues author Ian W. Roxburgh author Hossein Safari author Mathew Schofield author Sara Seager author Barry Smalley author Dennis Stello author Róbert Szabó author Jamie Tayar author Nathalie Themeßl author Alexandra E. L. Thomas author Roland K. Vanderspek author Walter E. van Rossem author Mathieu Vrard author Achim Weiss author Timothy R. White author Joshua N. Winn author Mutlu Yıldız author 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. Springer Nature2020 eng Astronomy and Astrophysics 2397-3366 2001.0465310.1038/s41550-019-0975-9 44382-389 yes Chaplin, W. J., Serenelli, A. M., Miglio, A., Morel, T., Mackereth, J. T., Vincenzo, F., … Yıldız, M. (2020). Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi. <i>Nature Astronomy</i>. Springer Nature. <a href="https://doi.org/10.1038/s41550-019-0975-9">https://doi.org/10.1038/s41550-019-0975-9</a> Chaplin, William J., Aldo M. Serenelli, Andrea Miglio, Thierry Morel, J. Ted Mackereth, Fiorenzo Vincenzo, Hans Kjeldsen, et al. “Age Dating of an Early Milky Way Merger via Asteroseismology of the Naked-Eye Star ν Indi.” <i>Nature Astronomy</i>. Springer Nature, 2020. <a href="https://doi.org/10.1038/s41550-019-0975-9">https://doi.org/10.1038/s41550-019-0975-9</a>. Chaplin, William J., et al. “Age Dating of an Early Milky Way Merger via Asteroseismology of the Naked-Eye Star ν Indi.” <i>Nature Astronomy</i>, vol. 4, no. 4, Springer Nature, 2020, pp. 382–89, doi:<a href="https://doi.org/10.1038/s41550-019-0975-9">10.1038/s41550-019-0975-9</a>. W.J. Chaplin, A.M. Serenelli, A. Miglio, T. Morel, J.T. Mackereth, F. Vincenzo, H. Kjeldsen, S. Basu, W.H. Ball, A. Stokholm, K. Verma, J.R. Mosumgaard, V. Silva Aguirre, A. Mazumdar, P. Ranadive, H.M. Antia, Y. Lebreton, J. Ong, T. Appourchaux, T.R. Bedding, J. Christensen-Dalsgaard, O. Creevey, R.A. García, R. Handberg, D. Huber, S.D. Kawaler, M.N. Lund, T.S. Metcalfe, K.G. Stassun, M. Bazot, P.G. Beck, K.J. Bell, M. Bergemann, D.L. Buzasi, O. Benomar, D. Bossini, L.A. Bugnet, T.L. Campante, Z.Ç. Orhan, E. Corsaro, L. González-Cuesta, G.R. Davies, M.P. Di Mauro, R. Egeland, Y.P. Elsworth, P. Gaulme, H. Ghasemi, Z. Guo, O.J. Hall, A. Hasanzadeh, S. Hekker, R. Howe, J.M. Jenkins, A. Jiménez, R. Kiefer, J.S. Kuszlewicz, T. Kallinger, D.W. Latham, M.S. Lundkvist, S. Mathur, J. Montalbán, B. Mosser, A.M. Bedón, M.B. Nielsen, S. Örtel, B.M. Rendle, G.R. Ricker, T.S. Rodrigues, I.W. Roxburgh, H. Safari, M. Schofield, S. Seager, B. Smalley, D. Stello, R. Szabó, J. Tayar, N. Themeßl, A.E.L. Thomas, R.K. Vanderspek, W.E. van Rossem, M. Vrard, A. Weiss, T.R. White, J.N. Winn, M. Yıldız, Nature Astronomy 4 (2020) 382–389. Chaplin WJ, Serenelli AM, Miglio A, Morel T, Mackereth JT, Vincenzo F, Kjeldsen H, Basu S, Ball WH, Stokholm A, Verma K, Mosumgaard JR, Silva Aguirre V, 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 PG, Bell KJ, Bergemann M, Buzasi DL, Benomar O, Bossini D, Bugnet LA, Campante TL, Orhan ZÇ, Corsaro E, González-Cuesta L, Davies GR, Di Mauro MP, 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, van Rossem WE, Vrard M, Weiss A, White TR, Winn JN, Yıldız M. 2020. Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi. Nature Astronomy. 4(4), 382–389. W. J. Chaplin <i>et al.</i>, “Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi,” <i>Nature Astronomy</i>, vol. 4, no. 4. Springer Nature, pp. 382–389, 2020. Chaplin WJ, Serenelli AM, Miglio A, et al. Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi. <i>Nature Astronomy</i>. 2020;4(4):382-389. doi:<a href="https://doi.org/10.1038/s41550-019-0975-9">10.1038/s41550-019-0975-9</a> 116112022-07-18T13:36:19Z2022-08-22T07:08:29Z