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 Searching for observational evidence of radial mixing in the Milky Way disk

2012 ◽  
Vol 10 (H16) ◽  
pp. 356-356
Author(s):  
Misha Haywood
Keyword(s):  
Large Scale ◽  
Milky Way ◽  
Theoretical Studies ◽  
Secular Evolution ◽  
Chemical Gradients ◽  
Current State ◽  
The Galaxy ◽  
The Subject ◽  
The Mean ◽  
State Of Affairs

AbstractSecular evolution in disks through angular momentum redistribution of stars induce radial mixing of their orbits. While theoretical studies and simulations now abound on the subject - with various predicted effects: disks growth, flattening of metallicity gradients, possible reversing of the mean age as a function of radius in disk, etc, observational evidences remain sparse. In the Galaxy, possible signatures are searched for in the local distributions of velocities, abundances and ages, or in the variation of large scale chemical gradients with time. I will present the current state of affairs and discuss what kind of evidences is available from data in the Milky Way.

VVV Microlensing events in the far side of the Milky Way

2019 ◽  
Vol 14 (S353) ◽  
pp. 35-37
Author(s):  
María Gabriela Navarro ◽  
Dante Minniti ◽  
Rodrigo Contreras Ramos
Keyword(s):  
Milky Way ◽  
The Other ◽  
Line Of Sight ◽  
Galactic Bulge ◽  
Near Ir ◽  
The Galaxy ◽  
Different Populations ◽  
First Time

AbstractIn order to study the most reddened areas of the Milky Way we used near-IR data from the VVV Survey. For the first time, the VISTA telescope allows us to observe the mid-plane through the Galactic bulge and study the disk in the other side of the Milky Way. Motivated by the detection of hundreds of microlensing events in the inner regions of the Galaxy, we propose three new configurations of microlensing events, placing the sources in the far-disk and the lenses in the far-disk/bulge/near-disk. These new configurations will change the usual way to interpret the timescale distributions due to the different populations along the line of sight, that exhibit varied transverse velocities and relative distances.

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 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 Secular evolution in galaxies

1985 ◽  
Vol 106 ◽  
pp. 613-614
Author(s):  
A. May ◽  
C. A. Norman ◽  
T.S. Van Albada
Keyword(s):  
The Other ◽  
Triaxial Ellipsoid ◽  
Galactic Bulge ◽  
Secular Evolution ◽  
Stellar Component ◽  
Starting Model

We have adapted the N-body code of Van Albada (1982) to study the secular evolution of a hot collisionless stellar component (E galaxy or galactic bulge) due to slow changes in another component of the same galaxy. Our equilibrium starting model is a non-rotating triaxial ellipsoid with axial ratios 1.3:1.4:2.0; the effects of the “other component” are then simulated by various simple means.

scholarly journals The Future of Stellar Populations Studies in the Milky Way and the Local Group

2009 ◽  
Vol 5 (S262) ◽  
pp. 99-110
Author(s):  
Steven R. Majewski
Keyword(s):  
Galaxy Evolution ◽  
Large Scale ◽  
Milky Way ◽  
Local Group ◽  
Time Series Data ◽  
Theoretical Models ◽  
Stellar Populations ◽  
Variable Stars ◽  
Series Data ◽  
The Future

AbstractThe last decade has seen enormous progress in understanding the structure of the Milky Way and neighboring galaxies via the production of large-scale digital surveys of the sky like 2MASS and SDSS, as well as specialized, counterpart imaging surveys of other Local Group systems. Apart from providing snaphots of galaxy structure, these “cartographic” surveys lend insights into the formation and evolution of galaxies when supplemented with additional data (e.g., spectroscopy, astrometry) and when referenced to theoretical models and simulations of galaxy evolution. These increasingly sophisticated simulations are making ever more specific predictions about the detailed chemistry and dynamics of stellar populations in galaxies. To fully exploit, test and constrain these theoretical ventures demands similar commitments of observational effort as has been plied into the previous imaging surveys to fill out other dimensions of parameter space with statistically significant intensity. Fortunately the future of large-scale stellar population studies is bright with a number of grand projects on the horizon that collectively will contribute a breathtaking volume of information on individual stars in Local Group galaxies. These projects include: (1) additional imaging surveys, such as Pan-STARRS, SkyMapper and LSST, which, apart from providing deep, multicolor imaging, yield time series data useful for revealing variable stars (including critical standard candles, like RR Lyrae variables) and creating large-scale, deep proper motion catalogs; (2) higher accuracy, space-based astrometric missions, such as Gaia and SIM-Lite, which stand to provide critical, high precision dynamical data on stars in the Milky Way and its satellites; and (3) large-scale spectroscopic surveys provided by RAVE, APOGEE, HERMES, LAMOST, and the Gaia spectrometer, which will yield not only enormous numbers of stellar radial velocities, but extremely comprehensive views of the chemistry of stellar populations. Meanwhile, previously dust-obscured regions of the Milky Way will continue to be systematically exposed via large infrared surveys underway or on the way, such as the various GLIMPSE surveys from Spitzer's IRAC instrument, UKIDSS, APOGEE, JASMINE and WISE.

scholarly journals Age dating the Galactic bar with the nuclear stellar disc

2020 ◽  
Vol 492 (3) ◽  
pp. 4500-4511 ◽  
Author(s):  
Junichi Baba ◽  
Daisuke Kawata
Keyword(s):  
Central Region ◽  
Near Infrared ◽  
Milky Way ◽  
Age Distribution ◽  
Stellar Populations ◽  
The Other ◽  
Age Dating ◽  
Stellar Disc ◽  
Space Astrometry ◽  
Bar Formation

ABSTRACT From the decades of the theoretical studies, it is well known that the formation of the bar triggers the gas funnelling into the central sub-kpc region and leads to the formation of a kinematically cold nuclear stellar disc (NSD). We demonstrate that this mechanism can be used to identify the formation epoch of the Galactic bar, using an N-body/hydrodynamics simulation of an isolated Milky Way–like galaxy. As shown in many previous literature, our simulation shows that the bar formation triggers an intense star formation for ∼1 Gyr in the central region and forms an NSD. As a result, the oldest age limit of the NSD is relatively sharp, and the oldest population becomes similar to the age of the bar. Therefore, the age distribution of the NSD tells us the formation epoch of the bar. We discuss that a major challenge in measuring the age distribution of the NSD in the Milky Way is contamination from other non-negligible stellar components in the central region, such as a classical bulge component. We demonstrate that because the NSD is kinematically colder than the other stellar populations in the Galactic central region, the NSD population can be kinematically distinguished from the other stellar populations, if the 3D velocity of tracer stars is accurately measured. Hence, in addition to the line-of-sight velocities from spectroscopic surveys, the accurate measurements of the transverse velocities of stars are necessary, and hence the near-infrared space astrometry mission, JASMINE, would play a crucial role to identify the formation epoch of the Galactic bar. We also discuss that the accuracy of stellar age estimation is also crucial to measure the oldest limit of the NSD stellar population.

scholarly journals Fast and slow rotators: the build-up of the red sequence

2007 ◽  
Vol 3 (S245) ◽  
pp. 11-14
Author(s):  
Eric Emsellem ◽  
Michele Cappellari ◽  
Davor Krajnović ◽  
Glenn van de Ven ◽  
R. Bacon ◽  
...  
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Large Scale ◽  
Stellar Populations ◽  
Matter Content ◽  
Orbital Structure ◽  
Early Type ◽  
Secular Evolution ◽  
Unique Dataset ◽  
Red Sequence

AbstractUsing the unique dataset obtained within the course of theSAURONproject, a radically new view of the structure, dynamics and stellar populations of early-type galaxies has emerged. We show that galaxies come in two broad flavours (slow and fast rotators), depending on whether or not they exhibit clear large-scale rotation, as indicated via a robust measure of the specific angular momentum of baryons. This property is also linked with other physical characteristics of early-type galaxies, such as: the presence of dynamically decoupled cores, orbital structure and anisotropy, stellar populations and dark matter content. I here report on the observed link between this baryonic angular momentum and a mass sequence, and how this uniquely relates to the building of the red sequence via dissipative/dissipationless mergers and secular evolution.

scholarly journals The origin of stellar populations in the Galactic bulge from chemical abundances

2019 ◽  
Vol 487 (4) ◽  
pp. 5363-5371 ◽  
Author(s):  
F Matteucci ◽  
V Grisoni ◽  
E Spitoni ◽  
A Zulianello ◽  
A Rojas-Arriagada ◽  
...  
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Formation Rate ◽  
Age Distribution ◽  
Stellar Populations ◽  
Distribution Functions ◽  
Galactic Bulge ◽  
Chemical Abundances ◽  
Abundance Pattern ◽  
Secular Evolution

ABSTRACT In this work, we study the formation and chemical evolution of the Galactic bulge with particular focus on the abundance pattern ([Mg/Fe] versus [Fe/H]), metallicity, and age distribution functions. We consider detailed chemical evolution models for the Galactic bulge and inner disc, with the aim of shedding light on the connection between these components and the origin of bulge stars. In particular, we first present a model assuming a fast and intense star formation, with the majority of bulge stars forming on a time-scale less than 1 Gyr. Then we analyse the possibility of two distinct stellar populations in the bulge, as suggested by Gaia-ESO and APOGEE data. These two populations, one metal poor and the other metal rich, can have had two different origins: (i) the metal rich formed after a stop of ∼250 Myr in the star formation rate of the bulge or (ii) the metal-rich population is made of stars formed in the inner disc and brought into the bulge by the early secular evolution of the bar. We also examine the case of multiple starbursts in the bulge with consequent formation of multiple populations, as suggested by studies of microlensed stars. After comparing model results and observations, we suggest that the most likely scenario is that there are two main stellar populations, both made mainly by old stars (>10 Gyr), with the metal-rich and younger one formed from inner thin disc stars, in agreement with kinematical arguments. However, on the basis of dynamical simulations, we cannot completely exclude that the second population formed after a stop in the star formation during the bulge evolution, so that all the stars formed in situ.

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