The Galactic Bulge
نویسنده
چکیده
The Galactic bulge is the least studied component of our Galaxy. Yet, its formation and evolution are key to understand the formation of the Galaxy itself. Studies on the Galactic bulge have increased significantly in the last years, but still there are many points of controversy. This volume contains several contributions from experts in different aspects of the bulge. Issues discussed include the following: the presence of an old spheroidal bulge, or identification of its old stellar population with the thick disk or halo; fraction of stars younger than 10 Gyr is estimated to be of< 5 to 22% depending on method and authors; multiple populations or only a metal-poor and a metal-rich ones; spheroidal or ellipsoidal distribution of RR Lyrae; formation of the bulge from early mergers or from secular evolution of the bar; different methods of mapping extinction; selection and identification of bulge globular clusters.
منابع مشابه
Radial velocities of planetary nebulae towards the Galactic bulge
Accurate radial velocities for a sample of 71 planetary nebulae, mostly located in the direction of the Galactic Centre, are presented. Most of the nebulae discussed in this paper are likely members of the Galactic bulge, based on their radial velocity, longitude and derived distance. The data give a large improvement over existing catalogues, doubling the sample of bulge planetary nebulae with...
متن کاملKinematics and Composition of the Galactic Bulge : Recent Progress
We present recent results from a Keck study of the composition of the Galactic bulge, as well as results from the bulge Bulge Radial Velocity Assay (BRAVA). Culminating a 10 year investigation, Fulbright, McWilliam, & Rich (2006, 2007) solved the problem of deriving the iron abundance in the Galactic bulge, and find enhanced alpha element abundances, consistent with the earlier work of McWillia...
متن کاملStudying the Galactic Bulge Through Spectroscopy of Microlensed Sources: I. Theoretical Considerations
The observed spectra of the microlensed sources towards the Galactic bulge may be used as a tool for studying the kinematics and extinction effects in the Galactic bulge. In this paper, we first investigate the expected distribution of the microlensed sources as a function of depth within the Galactic bulge. Our analysis takes a magnitude limited microlensing survey into account, and includes t...
متن کاملObservations of planetary nebulae in the Galactic Bulge
High quality spectrophotometric observations of 30 Planetary Nebulae in the Galactic Bulge have been made. Accurate reddenings, plasma parameters, and abundances of He, O, N, S, Ar, Cl are derived. We find the abundances of O, S, Ar in the Planetary Nebulae in the Galactic Bulge to be comparable with the abundances of the Planetary Nebulae in the Disk, high abundances being maybe slightly more ...
متن کاملDistribution of the Galactic Bulge emission at | b | > 2 ◦ according to the RXTE Galactic Center scans
We present an analysis of the Galactic bulge emission observed by the RXTE/PCA during a set of scans over the Galactic Center field, performed in 1999–2001. The total exposure time of these observations is close to 700 ks. We construct the distribution of Galactic ridge emission intensity and spectral parameters up to Galactic latitudes b ∼ −10◦;+9◦. We show that the intensity distribution of t...
متن کاملThe Galactic Bulge: the Stellar and Planetary Nebulae Populations
We compare abundances patterns in the Bulge for elements observed in stars and in planetary nebulae. Some α elements, like Mg and Ti, are overabundant in respect to Fe, and others are not, like He, O, Si, S, Ar, Ca. The first ones favor a quick evolution of the Galactic Bulge, and the seconds a much slower one.
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