A NEW STELLAR CHEMO-KINEMATIC RELATION REVEALS THE MERGER HISTORY OF THE MILKY WAY DISK

Journal Article · Mon Jan 20 00:00:00 EST 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/781/1/L20· OSTI ID:22364031

Minchev, I.; Chiappini, C.; Steinmetz, M.; De Jong, R. S.; Scannapieco, C. ^[1]; Martig, M. ^[2]; Boeche, C.; Grebel, E. K. ^[3]; Zwitter, T. ^[4]; Wyse, R. F. G. ^[5]; Binney, J. J. ^[6]; Bland-Hawthorn, J. ^[7]; Bienaymé, O.; Famaey, B. ^[8]; Freeman, K. C. ^[9]; Gibson, B. K. ^[10]; Gilmore, G.; Kordopatis, G. ^[11]; Helmi, A. ^[12]; Lee, Y. S. ^[13] ; others, and

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1. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
2. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia)
3. Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, D-69120 Heidelberg (Germany)
4. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia)
5. Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
6. Rudolf Peierls Centre for Theoretical Physics, Keble Road, Oxford OX1 3NP (United Kingdom)
7. Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia)
8. CNRS, Observatoire Astronomique, Université de Strasbourg, 11 rue de l'Université, F-67000 Strasbourg (France)
9. Australian National University, Canberra, ACT 0200 (Australia)
10. Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)
11. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
12. Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700-AV Groningen (Netherlands)
13. Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)

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.

• OSTI ID: 22364031
• Journal Information: Astrophysical Journal Letters, Vol. 781, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DISTURBANCES
GIANT STARS
IRON
METALLICITY
MILKY WAY
RADIAL VELOCITY
STAR CLUSTERS
STAR EVOLUTION
SUN
UNIVERSE