scholarly journals Existence of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy

2020 ◽  
Vol 903 (2) ◽  
pp. 131
Author(s):  
Yepeng Yan ◽  
Cuihua Du ◽  
Hefan Li ◽  
Jianrong Shi ◽  
Jun Ma ◽  
...  
Keyword(s):  
High Velocity ◽  
Thick Disk ◽  
The Galaxy ◽  
Stellar Halo

scholarly journals Element Abundance Analysis of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy

2021 ◽  
Vol 915 (1) ◽  
pp. 9
Author(s):  
Haifan Zhu ◽  
Cuihua Du ◽  
Yepeng Yan ◽  
Jianrong Shi ◽  
Jun Ma ◽  
...  
Keyword(s):  
High Velocity ◽  
Thick Disk ◽  
Element Abundance ◽  
The Galaxy ◽  
Stellar Halo

scholarly journals The Age of Old Galactic Populations

1998 ◽  
Vol 11 (1) ◽  
pp. 560-561
Author(s):  
M. Grenon
Keyword(s):  
High Velocity ◽  
Radial Velocities ◽  
Thick Disk ◽  
Early Evolution ◽  
Galactic Bulge ◽  
Colour Class ◽  
The Galaxy ◽  
Nearby Stars

As a preparation to the HIPPARCOS mission, a large observing programme on NLTT stars (propermotion > 0.18 ″/yr) was started in Genevaphotometry. The original programme consists of 10047 stars brighter than mR = 11.5, or mR = 12.5 if of colour class m. Among them, 7813 targets could be included in the HIPPARCOS programme, selected according to their observability and internal priorities in favour of large parallaxe stars (photometric distances < 100 pc) and high-velocity stars. The bulk of new nearby, halo, mild-metal poor and SMR stars in the HIP Catalogue originates from this proposal (N° 139). No less than 208 new nearby stars with π ≥ 40 mas were discovered south of δ +10°, the closest has π(HIP)= 182 mas. Radial velocities were obtained with CORAVEL at OHP and ESO. Most aspects of the early evolution of the Galaxy may be addressed with this sample. Here we discuss, as examples, the ages of the thick disk and of the galactic bulge.

scholarly journals Evolution of the Galactic Halo and Disk

1995 ◽  
Vol 164 ◽  
pp. 99-107
Author(s):  
Gerard Gilmore
Keyword(s):  
Angular Momentum ◽  
Galactic Halo ◽  
Evolutionary Model ◽  
Thick Disk ◽  
Structural Components ◽  
Stellar Kinematics ◽  
Chemical Abundances ◽  
The Galaxy ◽  
Stellar Halo ◽  
Discrete Populations

Correlations between stellar kinematics and chemical abundances are fossil evidence for evolutionary connections between Galactic structural components. Extensive stellar surveys show that the only tolerably clear distinction between galactic components appears in the distributions of specific angular momentum. Here the stellar metal-poor halo and the metal-rich bulge are indistinguishable from each other, as are the thick disk and the old disk. Each pair is very distinct from the other. This leads to an evolutionary model in which the metal-poor stellar halo evolves into the inner bulge, while the thick disk is a precursor to the thin disk. These evolutionary sequences are distinct. The galaxy is made of two discrete “populations”, one of low and one of high angular momentum. Some (minor?) complexity is added to this picture by the debris of late and continuing mergers, which will be especially important in the outer stellar halo.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

scholarly journals Abundances in the Gaseous Galactic Halo

1998 ◽  
Vol 11 (1) ◽  
pp. 86-89
Author(s):  
Ulysses J. Sofia
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
High Velocity ◽  
Galactic Halo ◽  
Solar Neighborhood ◽  
Local Interstellar Medium ◽  
The Galaxy ◽  
Metal Abundances ◽  
High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

scholarly journals The merger that led to the formation of the Milky Way’s inner stellar halo and thick disk

Nature ◽  
2018 ◽  
Vol 563 (7729) ◽  
pp. 85-88 ◽  
Author(s):  
Amina Helmi ◽  
Carine Babusiaux ◽  
Helmer H. Koppelman ◽  
Davide Massari ◽  
Jovan Veljanoski ◽  
...  
Keyword(s):  
Thick Disk ◽  
Stellar Halo

scholarly journals The High-velocity Stars in the Local Stellar Halo from Gaia and LAMOST

2018 ◽  
Vol 863 (1) ◽  
pp. 87 ◽  
Author(s):  
Cuihua Du ◽  
Hefan Li ◽  
Shuai Liu ◽  
Thomas Donlon ◽  
Heidi Jo Newberg
Keyword(s):  
High Velocity ◽  
Stellar Halo

scholarly journals The chemical fingerprints of the thin and the thick disk

2008 ◽  
Vol 4 (S254) ◽  
pp. 197-202
Author(s):  
Sofia Feltzing ◽  
Sally Oey ◽  
Thomas Bensby
Keyword(s):  
Past History ◽  
Thick Disk ◽  
Chemical Abundance ◽  
Dwarf Stars ◽  
Abundance Patterns ◽  
The Galaxy ◽  
Thin And Thick Disks ◽  
Thick Disks ◽  
Definition Of ◽  
Galactic Stellar Populations

AbstractThe past history and origin of the different Galactic stellar populations are manifested in their different chemical abundance patterns. We obtained new elemental abundances for 553 F and G dwarf stars, to more accurately quantify these patterns for the thin and thick disks. However, the exact definition of disk membership is not straightforward. Stars that have a high likelihood of belonging to the thin disk show different abundance patterns from those for the thick disk. In contrast, we show that stars for the Hercules Stream do not show unique abundance patterns, but rather follow those of the thin and thick disks. This strongly suggests that the Hercules Stream is a feature induced by internal dynamics within the Galaxy rather than the remnant of an accreted satellite.

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