The formation of a thick disk through the heating of a thin disk: Agreement with orbital eccentricities of stars in the solar neighborhood

Matteo, P. Di; Lehnert, M. D.; Qu, Yuanzhi; Driel, W.D. van

doi:10.1051/0004-6361/201015822

Cited by 61 publications

(60 citation statements)

References 17 publications

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“…The similar chemical composition of stars in Group 3 and the thick-disc stars might suggest that their formation histories are linked. The kinematic properties of our stellar group fit well with a gas-rich satellite merger scenario (Brook et al 2004(Brook et al , 2005Dierickx et al 2010;Wilson et al 2011;Di Matteo et al 2011, and references therein). We plan to increase the number of stars and chemical elements investigated in this group, and also to study the chemical composition of stars in other kinematic groups of the GenevaCopenhagen survey.…”

Section: Discussionsupporting

confidence: 77%

“…The group of stars investigated in our work fits this model with a mean eccentricity value of 0.4. This scenario is also supported by the RAVE survey data analysis made by Wilson et al (2011) and the numerical simulations by Di Matteo et al (2011). In this scenario, Group 3 can be explained as a remnant from stars originally formed in a merging satellite.…”

Section: Comparison With the Thin-and Thick-disc Dwarfsmentioning

confidence: 55%

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Stellar substructures in the solar neighbourhood

Stonkutė

Tautvaišienė

Nordström

et al. 2012

A&A

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Context. Galactic archeology is a powerful tool for investigating the formation and evolution of the Milky Way. We use this technique to study kinematic groups of F-and G-stars in the solar neighbourhood. From correlations between orbital parameters, three new coherent groups of stars were recently identified and suggested to correspond to remnants of disrupted satellites. Aims. We determine detailed elemental abundances in stars belonging to one of these groups and compare their chemical composition with Galactic disc stars. The aim is to look for possible chemical signatures that might give information about the history of this kinematic group of stars. Methods. High-resolution spectra were obtained with the FIES spectrograph at the Nordic Optical Telescope, La Palma, and analysed with a differential model atmosphere method. Comparison stars were observed and analysed with the same method. Results. The average value of [Fe/H] for the 20 stars investigated in this study is −0.69 ± 0.05 dex. Elemental abundances of oxygen and α-elements are overabundant in comparison with Galactic thin-disc dwarfs and thin-disc chemical evolution models. This abundance pattern has similar characteristics as the Galactic thick-disc. Conclusions. The homogeneous chemical composition together with the kinematic properties and ages of stars in the investigated Group 3 of the Geneva-Copenhagen survey provides evidence of their common origin and possible relation to an ancient merging event. The similar chemical composition of stars in the investigated group and the thick-disc stars might suggest that their formation histories are linked.

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Section: Discussionsupporting

confidence: 77%

Section: Comparison With the Thin-and Thick-disc Dwarfsmentioning

confidence: 55%

Stellar substructures in the solar neighbourhood

Stonkutė

Tautvaišienė

Nordström

et al. 2012

A&A

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“…In particular, the shape of the e distribution of the thick disk stars does not differ much from the disk heating model of Di Matteo et al (2011).…”

Section: Stellar Orbital Eccentricitiesmentioning

confidence: 74%

“…In this paper, to provide constraints on the various suggested formation models, we explore the stellar orbital eccentricity distributions (e.g., Sales et al 2009;Di Matteo et al 2011), a possible correlation between the eccentricities and metallicity (see Lee et al 2011), and rotational velocity gradients with metallicity in the thin and thick disks (e.g., Lee et al 2011;Kordopatis et al 2011;Navarro et al 2011;Liu & van de Ven 2012).…”

Section: Introductionmentioning

confidence: 99%

Kinematics and chemical properties of the Galactic stellar populations

Adibekyan

Figueira

Santos

et al. 2013

A&A

158

202

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Aims. We analyzed chemical and kinematical properties of about 850 FGK solar neighborhood long-lived dwarfs observed with the HARPS high-resolution spectrograph. The stars in the sample have log g ≥ 4 dex, 5000 ≤ T eff ≤ 6500 K, and −1.39 ≤ [Fe/H] ≤ 0.55 dex. The aim of this study is to characterize and explore the kinematics and chemical properties of stellar populations of the Galaxy in order to understand their origins and evolution. Methods. We applied a purely chemical analysis approach based on the [α/Fe] vs. [Fe/H] plot to separate Galactic stellar populations into the thin disk, thick disk, and high-α metal-rich (hαmr). Then, we explored the population's stellar orbital eccentricity distributions, their correlation with metallicity, and rotational velocity gradients with metallicity in the Galactic disks to provide constraints on the various formation models. Results. We identified a gap in the [α/Fe]-[Fe/H] plane for the α-enhanced stars, and by performing a bootstrapped Monte Carlo test we obtained a probability higher than 99.99% that this gap is not due to small-number statistics. Our analysis shows a negative gradient of the rotational velocity of the thin disk stars with [Fe/H] (-17 km s −1 dex −1 ), and a steep positive gradient for both the thick disk and hαmr stars with the same magnitude of about +42 km s −1 dex −1 . For the thin disk stars we observed no correlation between orbital eccentricities and metallicity, but observed a steep negative gradient for the thick disk and hαmr stars with practically the same magnitude (≈-0.18 dex −1 ). The correlations observed for the nearby stars (on average 45 pc) using high-precision data, in general agree well with the results obtained for the SDSS sample of stars located farther from the Galactic plane. Conclusions. Our results suggest that radial migration played an important role in the formation and evolution of the thin disk. For the thick disk stars it is not possible to reach a firm conclusion about their origin. Based on the eccentricity distribution of the thick disk stars only their accretion origin can be ruled out, and the heating and migration scenario could explain the positive steep gradient of V φ with [Fe/H]. When we analyzed the hαmr stellar population we found that they share properties of both the thin and thick disk population. A comparison of the properties of the hαmr stars with those of the subsample of stars from the N-body/SPH simulation using radial migration suggest that they may have originated from the inner Galaxy. Further detailed investigations would help to clarify their exact nature and origin.

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“…Another possibility is that thick discs are created through the heating of preexisting thin discs by minor mergers (Di Matteo et al 2011;Villalobos & Helmi 2008). Evidence for merger encounters can be found in the phasespace structure of Milky Way disc stars (e.g., Gómez et al 2013Gómez et al , 2012bMinchev et al 2009).…”

Section: The Galactic Thick Discmentioning

confidence: 99%

Constraining the Milky Way assembly history with Galactic Archaeology

Minchev

2016

Astron Nachr

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The aim of Galactic Archaeology is to recover the evolutionary history of the Milky Way from its present day kinematical and chemical state. Because stars move away from their birth sites, the current dynamical information alone is not sufficient for this task. The chemical composition of stellar atmospheres, on the other hand, is largely preserved over the stellar lifetime and, together with accurate ages, can be used to recover the birthplaces of stars currently found at the same Galactic radius. In addition to the availability of large stellar samples with accurate 6D kinematics and chemical abundance measurements, this requires detailed modeling with both dynamical and chemical evolution taken into account. An important first step is to understand the variety of dynamical processes that can take place in the Milky Way, including the perturbative effects of both internal (bar and spiral structure) and external (infalling satellites) agents. We discuss here (1) how to constrain the Galactic bar, spiral structure, and merging satellites by their effect on the local and global disc phase-space, (2) the effect of multiple patterns on the disc dynamics, and (3) the importance of radial migration and merger perturbations for the formation of the Galactic thick disc. Finally, we discuss the construction of Milky Way chemo-dynamical models and relate to observations.

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The formation of a thick disk through the heating of a thin disk: Agreement with orbital eccentricities of stars in the solar neighborhood

Cited by 61 publications

References 17 publications

Stellar substructures in the solar neighbourhood

Stellar substructures in the solar neighbourhood

Kinematics and chemical properties of the Galactic stellar populations

Constraining the Milky Way assembly history with Galactic Archaeology

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