A new stellar chemo-kinematic relation reveals the merger history of the milky way disk

I. Minchev; C. Chiappini; M. Martig; M. Steinmetz; R. S. De Jong; C. Boeche; C. Scannapieco; T. Zwitter; R. F. G. Wyse; J. J. Binney; J. Bland-Hawthorn; O. Bienaymé; B. Famaey; K. C. Freeman; B. K. Gibson; E. K. Grebel; G. Gilmore; A. Helmi; G. Kordopatis; Y. S. Lee; U. Munari; J. F. Navarro; Q. A. Parker; A. C. Quillen; W. A. Reid; A. Siebert; A. Siviero; G. Seabroke; F. Watson; M. Williams

doi:10.1088/2041-8205/781/1/L20

A new stellar chemo-kinematic relation reveals the merger history of the milky way disk

I. Minchev, C. Chiappini, M. Martig, M. Steinmetz, R. S. De Jong, C. Boeche, C. Scannapieco, T. Zwitter, R. F. G. Wyse, J. J. Binney, J. Bland-Hawthorn, O. Bienaymé, B. Famaey, K. C. Freeman, B. K. Gibson, E. K. Grebel, G. Gilmore, A. Helmi, G. Kordopatis, Y. S. LeeU. Munari, J. F. Navarro, Q. A. Parker, A. C. Quillen, W. A. Reid, A. Siebert, A. Siviero, G. Seabroke, F. Watson, M. Williams

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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.

Original language	English
Article number	L20
Pages (from-to)	1-6
Number of pages	6
Journal	Astrophysical Journal Letters
Volume	781
Issue number	1
DOIs	https://doi.org/10.1088/2041-8205/781/1/L20
Publication status	Published - Jan 2014

Bibliographical note

Copyright 2014 The American Astronomical Society. Firstly published in the Astrophysical Journal Letters, 781(1), L20, 2014, published by IOP Publishing. The original publication is available at http://www.doi.org/10.1088/2041-8205/781/1/L20. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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10.1088/2041-8205/781/1/L20

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Minchev, I., Chiappini, C., Martig, M., Steinmetz, M., De Jong, R. S., Boeche, C., Scannapieco, C., Zwitter, T., Wyse, R. F. G., Binney, J. J., Bland-Hawthorn, J., Bienaymé, O., Famaey, B., Freeman, K. C., Gibson, B. K., Grebel, E. K., Gilmore, G., Helmi, A., Kordopatis, G., ... Williams, M. (2014). A new stellar chemo-kinematic relation reveals the merger history of the milky way disk. Astrophysical Journal Letters, 781(1), 1-6. Article L20. https://doi.org/10.1088/2041-8205/781/1/L20

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title = "A new stellar chemo-kinematic relation reveals the merger history of the milky way disk",

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.",

author = "I. Minchev and C. Chiappini and M. Martig and M. Steinmetz and {De Jong}, {R. S.} and C. Boeche and C. Scannapieco and T. Zwitter and Wyse, {R. F. G.} and Binney, {J. J.} and J. Bland-Hawthorn and O. Bienaym{\'e} and B. Famaey and Freeman, {K. C.} and Gibson, {B. K.} and Grebel, {E. K.} and G. Gilmore and A. Helmi and G. Kordopatis and Lee, {Y. S.} and U. Munari and Navarro, {J. F.} and Parker, {Q. A.} and Quillen, {A. C.} and Reid, {W. A.} and A. Siebert and A. Siviero and G. Seabroke and F. Watson and M. Williams",

note = "Copyright 2014 The American Astronomical Society. Firstly published in the Astrophysical Journal Letters, 781(1), L20, 2014, published by IOP Publishing. The original publication is available at http://www.doi.org/10.1088/2041-8205/781/1/L20. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

year = "2014",

month = jan,

doi = "10.1088/2041-8205/781/1/L20",

language = "English",

volume = "781",

pages = "1--6",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

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Minchev, I, Chiappini, C, Martig, M, Steinmetz, M, De Jong, RS, Boeche, C, Scannapieco, C, Zwitter, T, Wyse, RFG, Binney, JJ, Bland-Hawthorn, J, Bienaymé, O, Famaey, B, Freeman, KC, Gibson, BK, Grebel, EK, Gilmore, G, Helmi, A, Kordopatis, G, Lee, YS, Munari, U, Navarro, JF, Parker, QA, Quillen, AC, Reid, WA, Siebert, A, Siviero, A, Seabroke, G, Watson, F & Williams, M 2014, 'A new stellar chemo-kinematic relation reveals the merger history of the milky way disk', Astrophysical Journal Letters, vol. 781, no. 1, L20, pp. 1-6. https://doi.org/10.1088/2041-8205/781/1/L20

TY - JOUR

T1 - A new stellar chemo-kinematic relation reveals the merger history of the milky way disk

AU - Minchev, I.

AU - Chiappini, C.

AU - Martig, M.

AU - Steinmetz, M.

AU - De Jong, R. S.

AU - Boeche, C.

AU - Scannapieco, C.

AU - Zwitter, T.

AU - Wyse, R. F. G.

AU - Binney, J. J.

AU - Bland-Hawthorn, J.

AU - Bienaymé, O.

AU - Famaey, B.

AU - Freeman, K. C.

AU - Gibson, B. K.

AU - Grebel, E. K.

AU - Gilmore, G.

AU - Helmi, A.

AU - Kordopatis, G.

AU - Lee, Y. S.

AU - Munari, U.

AU - Navarro, J. F.

AU - Parker, Q. A.

AU - Quillen, A. C.

AU - Reid, W. A.

AU - Siebert, A.

AU - Siviero, A.

AU - Seabroke, G.

AU - Watson, F.

AU - Williams, M.

N1 - Copyright 2014 The American Astronomical Society. Firstly published in the Astrophysical Journal Letters, 781(1), L20, 2014, published by IOP Publishing. The original publication is available at http://www.doi.org/10.1088/2041-8205/781/1/L20. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2014/1

Y1 - 2014/1

N2 - 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.

AB - 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.

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U2 - 10.1088/2041-8205/781/1/L20

DO - 10.1088/2041-8205/781/1/L20

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SN - 2041-8205

VL - 781

SP - 1

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JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L20

ER -

A new stellar chemo-kinematic relation reveals the merger history of the milky way disk

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