Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi

Research output: Contribution to journalLetterpeer-review

Authors

  • Aldo M. Serenelli
  • Thierry Morel
  • Hans Kjeldsen
  • Sarbani Basu
  • Amalie Stokholm
  • Kuldeep Verma
  • Jakob Rørsted Mosumgaard
  • Victor Silva Aguirre
  • Anwesh Mazumdar
  • Pritesh Ranadive
  • H. M. Antia
  • Yveline Lebreton
  • Joel Ong
  • Thierry Appourchaux
  • Timothy R. Bedding
  • Jørgen Christensen-dalsgaard
  • Orlagh Creevey
  • Rafael A. García
  • Rasmus Handberg
  • Daniel Huber
  • Steven D. Kawaler
  • Mikkel Lund
  • Travis S. Metcalfe
  • Keivan G. Stassun
  • Michäel Bazot
  • Paul G. Beck
  • Keaton J. Bell
  • Maria Bergemann
  • Derek L. Buzasi
  • Othman Benomar
  • Diego Bossini
  • Lisa Bugnet
  • Tiago Campante
  • Zeynep Çelik Orhan
  • Enrico Corsaro
  • Lucía González-cuesta
  • Guy R Davies
  • Maria Pia Di Mauro
  • Ricky Egeland
  • Yvonne Elsworth
  • Patrick Gaulme
  • Hamed Ghasemi
  • Zhao Guo
  • Oliver Hall
  • Amir Hasanzadeh
  • Saskia Hekker
  • Rachel Howe
  • Jon M. Jenkins
  • Antonio Jiménez
  • René Kiefer
  • James S. Kuszlewicz
  • Thomas Kallinger
  • David W. Latham
  • Mia S. Lundkvist
  • Savita Mathur
  • Josefina Montalbán
  • Benoit Mosser
  • Andres Moya Bedón
  • Martin Nielsen
  • Sibel Örtel
  • Ben M. Rendle
  • George R. Ricker
  • Thaíse S. Rodrigues
  • Ian W. Roxburgh
  • Hossein Safari
  • Mathew Schofield
  • Sara Seager
  • Barry Smalley
  • Dennis Stello
  • Róbert Szabó
  • Jamie Tayar
  • Nathalie Themeßl
  • Alexandra E. L. Thomas
  • Roland K. Vanderspek
  • Walter Van Rossem
  • Mathieu Vrard
  • Achim Weiss
  • Timothy R. White
  • Joshua N. Winn
  • Mutlu Yıldız

Colleges, School and Institutes

Abstract

Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies 1. 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–Enceladus 1, 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.

Bibliographic note

Accepted for publication as a Letter in Nature Astronomy (26 pages, 7 figures, including main article and methods section)

Details

Original languageEnglish
Pages (from-to)382-389
Number of pages8
JournalNature Astronomy
Volume4
Issue number4
Early online date13 Jan 2020
Publication statusPublished - Apr 2020

Keywords

  • astro-ph.GA, astro-ph.SR

ASJC Scopus subject areas