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Profile picture Diane Feuillet

Diane Feuillet

Forskare

Profile picture Diane Feuillet

The GALAH survey : tracing the Milky Way’s formation and evolution through RR Lyrae stars

Författare

  • Valentina D’Orazi
  • Nicholas Storm
  • Andrew R. Casey
  • Vittorio F. Braga
  • Alice Zocchi
  • Giuseppe Bono
  • Michele Fabrizio
  • Christopher Sneden
  • Davide Massari
  • Riano E. Giribaldi
  • Maria Bergemann
  • Simon W. Campbell
  • Luca Casagrande
  • Richard de Grijs
  • Gayandhi De Silva
  • Maria Lugaro
  • Daniel B. Zucker
  • Angela Bragaglia
  • Diane Feuillet
  • Giuliana Fiorentino
  • Brian Chaboyer
  • Massimo Dall’Ora
  • Massimo Marengo
  • Clara E. Martínez-Vázquez
  • Noriyuki Matsunaga
  • Matteo Monelli
  • Joseph P. Mullen
  • David Nataf
  • Maria Tantalo
  • Frederic Thevenin
  • Fabio R. Vitello
  • Rolf Peter Kudritzki
  • Joss Bland-Hawthorn
  • Sven Buder
  • Ken Freeman
  • Janez Kos
  • Geraint F. Lewis
  • Karin Lind
  • Sarah Martell
  • Sanjib Sharma
  • Dennis Stello
  • Tomaž Zwitter
Visa allt

Summary, in English

Stellar mergers and accretion events have been crucial in shaping the evolution of the Milky Way (MW). These events have been dynamically identified and chemically characterized using red giants and main-sequence stars. RR Lyrae (RRL) variables can play a crucial role in tracing the early formation of the MW since they are ubiquitous, old (t ≥ 10 Gyr) low-mass stars and accurate distance indicators. We exploited Data Release 3 of the GALAH survey to identify 78 field RRLs suitable for chemical analysis. Using synthetic spectra calculations, we determined atmospheric parameters and abundances of Fe, Mg, Ca, Y, and Ba. Most of our stars exhibit halo-like chemical compositions, with an iron peak around [Fe/H] ≈ −1.40, and enhanced Ca and Mg content. Notably, we discovered a metal-rich tail, with [Fe/H] values ranging from −1 to approximately solar metallicity. This sub-group includes almost 1/4 of the sample, it is characterized by thin disc kinematics and displays sub-solar α-element abundances, marginally consistent with the majority of the MW stars. Surprisingly, they differ distinctly from typical MW disc stars in terms of the s-process elements Y and Ba. We took advantage of similar data available in the literature and built a total sample of 535 field RRLs for which we estimated kinematical and dynamical properties. We found that metal-rich RRLs (1/3 of the sample) likely represent an old component of the MW thin disc. We also detected RRLs with retrograde orbits and provided preliminary associations with the Gaia–Sausage–Enceladus, Helmi, Sequoia, Sagittarius, and Thamnos stellar streams.

Avdelning/ar

  • Geologiska institutionen
  • eSSENCE: The e-Science Collaboration

Publiceringsår

2024-06-01

Språk

Engelska

Sidor

137-162

Publikation/Tidskrift/Serie

Monthly Notices of the Royal Astronomical Society

Volym

531

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Oxford University Press

Ämne

  • Astronomy, Astrophysics and Cosmology

Nyckelord

  • Galaxy: abundances
  • Galaxy: disc
  • Galaxy: halo
  • stars: abundances
  • stars: Population II
  • stars: variables: RR Lyrae

Aktiv

Published

ISBN/ISSN/Övrigt

  • ISSN: 0035-8711