A new stellar chemo-kinematic relation reveals the merger history of the Milky Way disk

Minchev, Ivan (Mathematics professor); Chiappini, Cristina; Martig, Marie, 1983-; Steinmetz, Matthias, 1966-; Jong, Roelof Sybe de, 1965-; Boeche, Corrado; Scannapieco, Cecilia; Zwitter, Tomaž; Wyse, Rosemary F. G.; Binney, James, 1950-; Bland-Hawthorn, J. (Joss); Bienaymé, Olivier; Famaey, Benoit; Freeman, Ken, 1940-; Gibson, Brad K.; Grebel, Eva K.; Gilmore, Gerry, 1951-; Helmi, A. (Amina), 1970-; Kordopatis, Georges, 1985-; Lee, Young Sun (Astronomer); Munari, Ulisse; Navarro, Julio F. (Julio Fernando); Parker, Quentin A.; Quillen, Alice C.; Reid, Warren A. (Warren Alfred); Siebert, Arnaud, 1974-; Siviero, Alessandro; Seabroke, George; Watson, Fred (Fred G.); Williams, Mary E. K.

Galaxy : abundances; Galaxy : disk; Galaxy : evolution; Galaxy : formation; Galaxy : kinematics and dynamics; Solar neighbourhood
2014

Journal article


Rights
© 2014. The American Astronomical Society. All rights reserved.
Abstract

The velocity dispersions of stars near the Sun are known to increase with stellar age, but age can be difficult to determine, so a proxy like the abundance of α elements (e.g., Mg) with respect to iron, [α/Fe], is used. Here we report an unexpected behavior found in the velocity dispersion of a sample of giant stars from the Radial Velocity Experiment survey with high-quality chemical and kinematic information, in that it decreases strongly for stars with [Mg/Fe] > 0.4 dex (i.e., those that formed in the first gigayear of the Galaxy's life). These findings can be explained by perturbations from massive mergers in the early universe, which have affected the outer parts of the disk more strongly, and the subsequent radial migration of stars with cooler kinematics from the inner disk. Similar reversed trends in velocity dispersion are also found for different metallicity subpopulations. Our results suggest that the Milky Way disk merger history can be recovered by relating the observed chemo-kinematic relations to the properties of past merger events.

Publisher
The University of Hull
Peer reviewed
Yes
Language
English
Extent
1 MB
Identifier
hull:13035

Journal

Journal title
The astrophysical journal letters
Publication date
2014
Publisher
American Astronomical Society
DOI
10.1088/2041-8205/781/1/L20
ISSN (Print)
2041-8205
ISSN (Electronic)
2041-8213
Volume
781
Start page
L20-1
End page
L20-6
Notes

This is a copy of an article published in The astrophysical journal letters, 2014, v.781.

Link
Published article
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