Stellar Populations in the Galactic Bulge

1996 ◽  
Vol 169 ◽  
pp. 317-327
Author(s):  
H.J. Habing
Keyword(s):  
Milky Way ◽  
Stellar Populations ◽  
Galactic Bulge ◽  
Central Cluster ◽  
Intimate Connection ◽  
The Subject ◽  
Sgr A

In this review I discuss stars in the bulge of our Milky Way, but I exclude stars within a few parsec from Sgr A West; they are the subject of other reviews at this Symposium. We should, however, not forget that there may be an intimate connection between the central cluster and the bulge: bulge stars may eject matter that feeds the monster at the center and eruptions by this monster may have an important effect on the bulge.

scholarly journals Correlations between Kinematics and Metallicity in the Galactic Bulge: A Review

2016 ◽  
Vol 33 ◽  
Author(s):  
Carine Babusiaux
Keyword(s):  
Density Profile ◽  
Large Scale ◽  
Milky Way ◽  
Stellar Populations ◽  
The Other ◽  
Galactic Bulge ◽  
Secular Evolution

AbstractRecent large-scale surveys of galactic bulge stars allowed to build a detailed map of the bulge kinematics. The bulge exhibits cylindrical rotation consistent with a disky origin which evolved through bar-driven secular evolution. However, correlations between metallicity and kinematics complicate this picture. In particular a metal-poor component with distinct kinematic signatures has been detected. Its origin, density profile and link with the other Milky Way stellar populations are currently still poorly constrained.

scholarly journals ARGOS – III. Stellar populations in the Galactic bulge of the Milky Way

2013 ◽  
Vol 430 (2) ◽  
pp. 836-857 ◽  
Author(s):  
M. Ness ◽  
K. Freeman ◽  
E. Athanassoula ◽  
E. Wylie-de-Boer ◽  
J. Bland-Hawthorn ◽  
...  
Keyword(s):  
Milky Way ◽  
Stellar Populations ◽  
Galactic Bulge

scholarly journals Hot stars in the Galactic Center

1999 ◽  
Vol 193 ◽  
pp. 449-458
Author(s):  
Andreas Eckart ◽  
Thomas Ott ◽  
Reinhard Genzel ◽  
Dieter Lutz
Keyword(s):  
Black Hole ◽  
Near Infrared ◽  
Milky Way ◽  
Infrared Imaging ◽  
Galactic Center ◽  
Hot Stars ◽  
Massive Black Hole ◽  
Central Cluster ◽  
Short Period ◽  
Sgr A

The central parsec of our Galaxy is powered by a cluster of young massive hot stars which formed a few million years ago. Within that cluster the seven most luminous (L >105.75 L⊙) and moderately hot (T < 104.5 K) blue supergiants contribute half of the ionizing luminosity of that region. These stars probably formed when a dense cloud fell into the center < 107 years ago, was highly compressed there, and became gravitationally unstable. Over six years of high spatial resolution, near-infrared imaging and spectroscopy have made it possible to carry out a detailed investigation of the stars in the central cluster and its enclosed mass. As one result of a detailed variability study of the central cluster stars we found that the bright He I star IRS 16SW is a short-period variable with a period of ∼9.72 days. It is most likely an eclipsing binary with a lower mass limit of 100 solar masses. Line of sight velocities and proper motions have been measured for these hot stars (as well as ∼200 other stars) down to separations of less than five light days from the compact radio source Sgr A* at the dynamic center of the Milky Way. These confirmed measurements imply the presence of a central dark mass of 2.6 × 106 solar masses. The dark mass at the center of the Milky Way is currently the most compelling case for a massive black hole. Simple physical considerations show that this dark mass cannot consist of a stable cluster of stars, stellar remnants, substellar condensations or a degenerate gas of elementary particles but that at least 103 to 105 solar masses must be in the form of a massive black hole associated with Sgr A* itself.

scholarly journals Shaping Disk Galaxy Stellar Populations via Internal and External Processes

2012 ◽  
Vol 10 (H16) ◽  
pp. 372-372
Author(s):  
Rok Roškar
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
Milky Way ◽  
Stellar Populations ◽  
Radial Migration ◽  
Disk Formation ◽  
Process Understanding ◽  
History Of ◽  
Nearby Galaxies ◽  
Gas Accretion

AbstractIn recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.

scholarly journals Metal-poor globular clusters of the galactic bulge

2009 ◽  
Vol 5 (S265) ◽  
pp. 344-345
Author(s):  
B. Barbuy ◽  
S. Ortolani ◽  
M. Zoccali ◽  
V. Hill ◽  
D. Minniti ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Populations ◽  
Galactic Bulge ◽  
Abundance Pattern ◽  
Individual Stars

AbstractVery few abundance analyses of individual stars in metal-poor globular clusters in the galactic bulge are available. The main purpose of this study is to derive abundances in individual stars of such clusters, in order to establish their abundance pattern, trying to characterize the oldest bulge stellar populations.

scholarly journals Central Molecular Zone of the Milky Way: Star Formation in an extreme Environment

2015 ◽  
Vol 11 (S315) ◽  
pp. 163-166
Author(s):  
Jens Kauffmann
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Spatial Scales ◽  
Extreme Environment ◽  
Average Density ◽  
High Mass ◽  
Density Structure ◽  
Star Formation Activity ◽  
Order Of Magnitude ◽  
Sgr A

AbstractThe Central Molecular Zone (CMZ; inner ~100 pc) hosts some of the most dense and massive molecular clouds of the Milky Way. These clouds might serve as local templates for dense clouds seen in nearby starburst galaxies or in the early universe. The clouds have a striking feature: they form stars at a very slow pace, considering their mass and high average density. Here we use interferometer data from ALMA and the SMA to show that this slow star formation is a consequence of the cloud density structure: CMZ clouds have a very flat density structure. They might, for example, exceed the average density of the Orion A molecular cloud by an order of magnitude on spatial scales ~5 pc, but CMZ “cores” of ~0.1 pc radius have masses and densities lower than what is found in the Orion KL region. This absence of highest–density gas probably explains the suppression of star formation. The clouds are relatively turbulent, and ALMA observations of H2CO and SiO indicate that the turbulence is induced by high–velocity shocks. We speculate that these shocks might prevent the formation of high–mass cores. It has been argued that the state of CMZ clouds depends on their position along the orbit around Sgr A*. Our incomplete data indicate no evolution in the density structure, and only a modest evolution in star formation activity per unit mass.

scholarly journals Planetary nebulae in the inner Milky Way

2009 ◽  
Vol 5 (S265) ◽  
pp. 354-355
Author(s):  
Oscar Cavichia ◽  
Roberto D. D. Costa ◽  
Walter J. Maciel
Keyword(s):  
Statistical Analysis ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Galactic Bulge ◽  
Intermediate Mass ◽  
Disk Interface ◽  
The Galaxy ◽  
Outer Border ◽  
Good Agreement

AbstractNew abundances of planetary nebulae located towards the bulge of the Galaxy are derived based on observations made at LNA (Brazil). We present accurate abundances of the elements He, N, S, O, Ar, and Ne for 56 PNe located towards the galactic bulge. The data shows a good agreement with other results in the literature, in the sense that the distribution of the abundances is similar to those works. From the statistical analysis performed, we can suggest a bulge-disk interface at 2.2 kpc for the intermediate mass population, marking therefore the outer border of the bulge and inner border of the disk.

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