Chronologically dating the early assembly of the Milky Way

dc.contributor.authorMontalbán, Josefina
dc.contributor.authorMacKereth, J. Ted
dc.contributor.authorMiglio, Andrea
dc.contributor.authorVincenzo, Fiorenzo
dc.contributor.authorChiappini, Cristina
dc.contributor.authorBuldgen, Gaël
dc.contributor.authorFerguson, Jason W.
dc.descriptionClick on the DOI link to access the article (may not be free).en_US
dc.description.abstractThe standard cosmological model predicts that galaxies are built through hierarchical assembly on cosmological timescales$^{1,2}.$ The Milky Way, like other disk galaxies, underwent violent mergers and accretion of small satellite galaxies in its early history. Owing to Gaia Data Release $2^3$ and spectroscopic surveys$^4,$ the stellar remnants of such mergers have been identified$^{5–7}.$ The chronological dating of such events is crucial to uncover the formation and evolution of the Galaxy at high redshift, but it has so far been challenging due to difficulties in obtaining precise ages for these oldest stars. Here we combine asteroseismology—the study of stellar oscillations—with kinematics and chemical abundances to estimate precise stellar ages (~11%) for a sample of stars observed by the Kepler space mission$^8.$ Crucially, this sample includes not only some of the oldest stars that were formed inside the Galaxy but also stars formed externally and subsequently accreted onto the Milky Way. Leveraging this resolution in age, we provide compelling evidence in favour of models in which the Galaxy had already formed a substantial population of its stars (which now reside mainly in its thick disk) before the infall of the satellite galaxy Gaia-Enceladus/Sausage$^{5,6}$ around 10 billion years ago.en_US
dc.description.sponsorshipJ.M., J.T.M., A.M., F.V. and E.W. acknowledge support from the ERC Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. no. 772293). F.V. acknowledges the support of a Fellowship from the Center for Cosmology and AstroParticle Physics at The Ohio State University. M.V. is supported by FEDER - Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalização by grants PTDC/FIS-AST/30389/2017 and POCI-01-0145-FEDER-030389. C.C. acknowledges partial support from DFG Grant CH1188/2-1 and from the ChETEC COST Action (CA16117), supported by COST (European Cooperation in Science and Technology). G.B. acknowledges fundings from the SNF AMBIZIONE grant no. 185805 (Seismic inversions and modelling of transport processes in stars) and from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 833925, project STAREX). G.R.D. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (CartographY GA 804752). M.B.N. acknowledges support from the UK Space Agency. O.J.H. acknowledges the support of the UK Science and Technology Facilities Council (STFC). This article made use of AIMS, a software for fitting stellar pulsation data, developed in the context of the SPACEINN network, funded by the European Commission’s Seventh Framework Programme. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular, the institutions participating in the Gaia Multilateral Agreement. The computations described in this paper were performed using the University of Birmingham’s BlueBEAR HPC service, which provides a high-performance computing service to the university’s research community. See for more details. We thank S. McGee for reading and commenting on the manuscript.en_US
dc.identifier.citationMontalbán, J., Mackereth, J. T., Miglio, A., Vincenzo, F., Chiappini, C., Buldgen, G., . . . Chaplin, W. J. (2021). Chronologically dating the early assembly of the milky way. Nature Astronomy, doi:10.1038/s41550-021-01347-7en_US
dc.publisherSpringer Natureen_US
dc.relation.ispartofseriesNature Astronomy;
dc.rights.holderCopyright © 2021, The Author(s), under exclusive license to Springer Nature Limiteden_US
dc.subjectEarly universeen_US
dc.subjectGalaxies and clustersen_US
dc.subjectStellar evolutionen_US
dc.titleChronologically dating the early assembly of the Milky Wayen_US
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
1.59 KB
Item-specific license agreed upon to submission