Repository logo

Infoscience

  • English
  • French
Log In
Logo EPFL, École polytechnique fédérale de Lausanne

Infoscience

  • English
  • French
Log In
  1. Home
  2. Academic and Research Output
  3. Journal articles
  4. What is the Milky Way outer halo made of? High resolution spectroscopy of distant red giants
 
Loading...
Thumbnail Image
research article

What is the Milky Way outer halo made of? High resolution spectroscopy of distant red giants

Battaglia, G.
•
North, P.  
•
Jablonka, P.  
Show more
2017
Astronomy & Astrophysics

In a framework where galaxies form hierarchically, extended stellar haloes are predicted to be an ubiquitous feature around Milky Way-like galaxies and to consist mainly of the shredded stellar component of smaller galactic systems. The type of accreted stellar systems are expected to vary according to the specific accretion and merging history of a given galaxy, and so is the fraction of stars formed in situ versus accreted. Analysis of the chemical properties of Milky Way halo stars out to large Galactocentric radii can provide important insights into the properties of the environment in which the stars that contributed to the build-up of different regions of the MilkyWay stellar halo formed. In this work we focus on the outer regions of the MilkyWay stellar halo, by determining chemical abundances of halo stars with large present-day Galactocentric distances, > 15 kpc. The data-set we acquired consists of high resolution HET/HRS, Magellan/MIKE and VLT/UVES spectra for 28 red giant branch stars covering a wide metallicity range, 3 : 1. [Fe/H] less than or similar to -0.6. We show that the ratio of alpha-elements over Fe as a function of [Fe/H] for our sample of outer halo stars is not dissimilar from the pattern shown by MW halo stars from solar neighborhood samples. On the other hand, significant differences appear at [Fe/H] greater than or similar to -1.5 when considering chemical abundance ratios such as [Ba/Fe], [Na/Fe], [Ni/Fe], [Eu/Fe], [Ba/Y]. Qualitatively, this type of chemical abundance trends are observed in massive dwarf galaxies, such as Sagittarius and the Large Magellanic Cloud. This appears to suggest a larger contribution in the outer halo of stars formed in an environment with high initial star formation rate and already polluted by asymptotic giant branch stars with respect to inner halo samples.

  • Details
  • Metrics
Type
research article
DOI
10.1051/0004-6361/201731879
Web of Science ID

WOS:000418460200001

Author(s)
Battaglia, G.
•
North, P.  
•
Jablonka, P.  
•
Shetrone, M.
•
Minniti, D.
•
Diaz, M.
•
Starkenburg, E.
•
Savoy, M.
Date Issued

2017

Publisher

Edp Sciences S A

Published in
Astronomy & Astrophysics
Volume

608

Article Number

A145

Subjects

stars: abundances

•

Galaxy: halo

•

Galaxy: structure

•

Galaxy: formation

•

galaxies: interactions

Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LASTRO  
Available on Infoscience
January 15, 2018
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/144030
Logo EPFL, École polytechnique fédérale de Lausanne
  • Contact
  • infoscience@epfl.ch

  • Follow us on Facebook
  • Follow us on Instagram
  • Follow us on LinkedIn
  • Follow us on X
  • Follow us on Youtube
AccessibilityLegal noticePrivacy policyCookie settingsEnd User AgreementGet helpFeedback

Infoscience is a service managed and provided by the Library and IT Services of EPFL. © EPFL, tous droits réservés