Galactic Archeology with 4MOST

Feltzing, Sofia; Bensby, T.; Bergemann, M.; Chiappini, Cristina; Christlieb, N.; Cioni, M. R. L.; Helmi, Amina; Irwin, M. J.; Minchev, Ivan; Starkenburg, Else; Jong, Roelof de

doi:10.1017/s1743921317008730

Cited by 10 publications

(7 citation statements)

References 25 publications

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“…will be challenging but a worthwhile effort to further confirm our two-phase scenario for the origin and evolution of vertical disturbances in the disc. Our models of the outer disc are realistic enough to be useful to inform and motivate searches and spectroscopic follow-ups for kicked-up disc stars with ongoing/upcoming complementary surveys such as CFIS (Ibata et al 2017a,b), the Dark Energy Survey (DES), APOGEE-II (Zasowski et al 2017), WEAVE (Famaey et al 2016), 4MOST (Feltzing et al 2017), DESI (DESI Collaboration et al 2016). Finally, we note that it has been suggested in the past that the Sgr stream could be used to constrain the dwarf's orbital history (Johnston et al 1999).…”

Section: Discussionmentioning

confidence: 99%

The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy

Laporte

Johnston

Gómez

et al. 2018

Monthly Notices of the Royal Astronomical Society

241

238

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We present N-body simulations of a Sagittarius-like dwarf spheroidal galaxy (Sgr) that follow its orbit about the Milky Way (MW) since its first crossing of the Galaxy's virial radius to the present day. As Sgr orbits around the MW, it excites vertical oscillations, corrugating and flaring the Galactic stellar disc. These responses can be understood by a two-phase picture in which the interaction is first dominated by torques from the wake excited by Sgr in the MW dark halo before transitioning to tides from Sgr's direct impact on the disc at late times. We show for the first time that a massive Sgr model simultaneously reproduces the locations and motions of arc-like over densities, such as the Monoceros Ring and the Triangulum Andromeda stellar clouds, that have been observed at the extremities of the disc, while also satisfying the solar neighbourhood constraints on the vertical structure and streaming motions of the disc. In additional simulations, we include the Large Magellanic Cloud (LMC) self consistently with Sgr. The LMC introduces coupling through constructive and destructive interference, but no new corrugations. In our models, the excitation of the current structure of the outer disk can be traced to interactions as far back as 6-7 Gyr ago (corresponding to z 1). Given the apparently quiescent accretion history of the MW over this timescale, this places Sgr as the main culprit behind the vertical oscillations of the disc and the last major accretion event for the Galaxy with the capacity to modulate its chemodynamical structure.

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Section: Discussionmentioning

confidence: 99%

The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy

Laporte

Johnston

Gómez

et al. 2018

Monthly Notices of the Royal Astronomical Society

241

238

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“…Next-generation low and medium-resolution spectroscopic facilities such as WEAVE (Bonifacio et al 2016), or PFS (Takada et al 2014) are suitable for directly identifying mono-enriched second generation stars among MW field halo and dwarf satellite's stars, which will be the best targets for a follow-up high-resolution spectroscopy. Highresolution spectroscopic surveys for large samples of stars in the MW are also on-going or planned in the near future with high-resolution multi-object spectrographs such as the APOGEE (Majewski et al 2017), GALAH (De Silva et al 2015, and the 4MOST (Feltzing et al 2017) projects.…”

Section: Discussionmentioning

confidence: 99%

Descendants of the first stars: the distinct chemical signature of second-generation stars

Hartwig

Yoshida

Magg

et al. 2018

Monthly Notices of the Royal Astronomical Society

117

121

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Extremely metal-poor (EMP) stars in the Milky Way (MW) allow us to infer the properties of their progenitors by comparing their chemical composition to the metal yields of the first supernovae. This method is most powerful when applied to monoenriched stars, i.e. stars that formed from gas that was enriched by only one previous supernova. We present a novel diagnostic to identify this subclass of EMP stars. We model the first generations of star formation semi-analytically, based on dark matter halo merger trees that yield MW-like halos at the present day. Radiative and chemical feedback are included self-consistently and we trace all elements up to zinc. Monoenriched stars account for only ∼ 1% of second generation stars in our fiducial model and we provide an analytical formula for this probability. We also present a novel analytical diagnostic to identify mono-enriched stars, based on the metal yields of the first supernovae. This new diagnostic allows us to derive our main results independently from the specific assumptions made regarding Pop III star formation, and we apply it to a set of observed EMP stars to demonstrate its strengths and limitations. Our results may provide selection criteria for current and future surveys and therefore contribute to a deeper understanding of EMP stars and their progenitors.

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“…by the WEAVE and 4MOST projects, see e.g. Feltzing et al 2017). Lists of possible members according to our analyses are given in Table D.3 for the globular clusters, dSph, and UFD galaxies, and for the Magellanic Clouds.…”

Section: Galactic Satellitesmentioning

confidence: 99%

GaiaData Release 2

Helmi¹,

Leeuwen²,

McMillan³

et al. 2018

A&A

Self Cite

575

198

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Context. Aims. The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. Methods. Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. Results. Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the Milky Way are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9.1-2.6+6.2 × 1011 M⊙ based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. Conclusions. All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release.

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Galactic Archeology with 4MOST

Cited by 10 publications

References 25 publications

The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy

The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy

Descendants of the first stars: the distinct chemical signature of second-generation stars

GaiaData Release 2

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