| Issue |
EPJ Web of Conferences
Volume 19, 2012
Assembling the Puzzle of the Milky Way
|
|
|---|---|---|
| Article Number | 04007 | |
| Number of page(s) | 3 | |
| Section | Thick Disc Formation: New Observational Constraints and Alternative Scenarios | |
| DOI | https://doi.org/10.1051/epjconf/20121904007 | |
| Published online | 07 February 2012 | |
https://doi.org/10.1051/epjconf/20121904007
Chemo-orbital evidence from SDSS/SEGUE G dwarf stars for a mixed origin of the Galactic thick disk
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
a e-mail: liu@mpia.de
b e-mail: glenn@mpia.de
About 13,000 G dwarf within 7<R<9kpc and 0.5<|z|<3.0 kpc from the SDSS/SEGUE spectroscopic survey are used to study the origin of the Milky Way thick disk. Combining [α/Fe] and [Fe/H] measurements with six-dimensional position-velocity parameters, we find that the sample is composed of two distinct stellar populations. The metal-rich population encompasses the thin disk with α-deficient stars and smoothly extends into a thick disk with α-enhanced stars, consistent with an in-situ formation through radial migration. On the other hand, the metal-poor population with enhanced α-abundance, higher scale height, and disperse kinematical properties, is difficult to explain with radial migration but might have originated from gas-rich mergers. The thick disk of the Milky Way seems to have a mixed origin.
© Owned by the authors, published by EDP Sciences, 2012
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