Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 488, Issue 1, Pages 1235-1247Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stz1770
Keywords
Galaxy: formation; Galaxy: halo; Galaxy: kinematics and dynamics; Galaxy: stellar content
Categories
Funding
- Boustany Foundation
- Cambridge Commonwealth
- European & International Trust
- Isaac Newton Studentship
- Science and Technology Facilities Council of the United Kingdom
- Royal Society
- European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC [308024]
Ask authors/readers for more resources
The Gaia Sausage is the major accretion event that built the stellar halo of the Milky Way galaxy. Here, we provide dynamical and chemical evidence for a second substantial accretion episode, distinct from the Gaia Sausage. The Sequoia Event provided the bulk of the high-energy retrograde stars in the stellar halo, as well as the recently discovered globular cluster FSR 1758. There are up to six further globular clusters, including omega Centauri, as well as many of the retrograde substructures in Myeong et al., associated with the progenitor dwarf galaxy, named the Sequoia. The stellar mass in the Sequoia galaxy is similar to 5 x 10 M-circle dot, whilst the total mass is similar to 10(10)M(circle dot), as judged from abundance matching or from the total sum of the globular cluster mass. Although clearly less massive than the Sausage, the Sequoia has a distinct chemodynamical signature. The strongly retrograde Sequoia stars have a typical eccentricity of similar to 0.6, whereas the Sausage stars have no clear net rotation and move on predominantly radial orbits. On average, the Sequoia stars have lower metallicity by similar to 0.3 dex and higher abundance ratios as compared to the Sausage. We conjecture that the Sausage and the Sequoia galaxies may have been associated and accreted at a comparable epoch.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available