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The determination of the age of the bulge has led to two contradictory results. On the one side, the color-magnitude diagrams in different bulge fields seem to indicate a uniformly old ($>$10 Gyr) population. On the other side, individual…

Astrophysics of Galaxies · Physics 2016-10-05 M. Haywood , P. Di Matteo , O. Snaith , A. Calamida

A map of the projected density of the old stellar population of the Galactic Bulge region is reconstructed using 2MASS data. By making a combination of the H and K photometric bands, it is possible to overcome the effect of reddening, and…

Astrophysics · Physics 2009-11-07 C. Alard

Using modern isochrones with customized physics and carefully considered statistical techniques, we recompute the age distribution for a sample of 91 micro-lensed dwarfs in the Galactic bulge presented by Bensby et al. (2017) and do not…

Solar and Stellar Astrophysics · Physics 2023-03-29 Meridith Joyce , Christian I. Johnson , Tommaso Marchetti , R. Michael Rich , Iulia Simion , John Bourke

This paper is the second part of Garzon et al. (1997: ApJ 491, L31) in which we presented an outline of the analysis of 60 spectra from a follow-up program to the Two Micron Galactic Survey (TMGS) project in the l=27 deg., b=0 deg. area. In…

Despite the huge amount of photometric and spectroscopic efforts targetting the Galactic bulge over the past few years, its age distribution remains controversial owing to both the complexity of determining the age of individual stars and…

Astrophysics of Galaxies · Physics 2018-05-02 Edouard J. Bernard , Mathias Schultheis , Paola Di Matteo , Vanessa Hill , Misha Haywood , Annalisa Calamida

We present a detailed elemental abundance study of 90 F and G dwarf, turn-off and subgiant stars in the Galactic bulge. Based on high-resolution spectra acquired during gravitational microlensing events, stellar ages and abundances for 11…

In some scenarios for the formation of the Milky Way bulge the stellar population at the edges of the boxy bulge may be younger than those on the minor axis, or close to the Galactic center. So far the only bulge region where deep…

Astrophysics of Galaxies · Physics 2015-06-17 E. Valenti , M. Zoccali , A. Renzini , T. M. Brown , O. Gonzalez , D. Minniti , Victor P. Debattista , L. Mayer

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…

Astrophysics · Physics 2007-05-23 F. Cuisinier , W. J. Maciel , J. Köppen , A. Acker , B. Stenholm

The Galactic bulge is dominated by an old, metal rich stellar population. The possible presence and the amount of a young (a few Gyr old) minor component is one of the major issues debated in the literature. Recently, the bulge stellar…

Astrophysics of Galaxies · Physics 2016-09-21 F. R. Ferraro , D. Massari , E. Dalessandro , B. Lanzoni , L. Origlia , R. M. Rich , A. Mucciarelli , -

[ABRIDGED] Based on high-resolution (R~42000 to 48000) and high signal-to-noise (S/N~50 to 150) spectra obtained with UVES/VLT, we present detailed elemental abundances (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, and Ba) and stellar ages…

We report periods and JHKL observations for 648 oxygen-rich Mira variables found in two outer bulge fields at b=-7 degrees and l=+/-8 degrees and combine these with data on 8057 inner bulge Miras from the OGLE, Macho and 2MASS surveys,…

Solar and Stellar Astrophysics · Physics 2015-12-02 Robin M. Catchpole , Patricia A. Whitelock , Michael W. Feast , Shaun M. G. Hughes , Mike Irwin , Christophe Alard

Over the last decade there have been a series of results supporting the hypothesis of the existence of a long thin bar in the Milky Way with a half-length of 4.5 kpc and a position angle of around 45 deg. This is apparently a very different…

We present the first results of a pilot study aimed at understanding the influence of bars on the evolution of galaxy discs through the study of their stellar content. We examine here the kinematics, star formation history, mass-weighted,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Patricia Sanchez-Blazquez , Pierre Ocvirk , Brad K. Gibson , Isabel Perez , Reynier F. Peletier

Over the last decade a series of results have lent support to the hypothesis of the existence of a long thin bar in the Milky Way with a half-length of 4.5 kpc and a position angle of around 45 deg. This is apparently a very different…

Until recently our knowledge of the Galactic Bulge stellar populations was based on the study of a few low extinction windows. Large photometric and spectroscopic surveys are now underway to map large areas of the bulge. They probe several…

Astrophysics of Galaxies · Physics 2012-10-09 Carine Babusiaux

Context. The formation and evolution of the Milky Way bulge is still largely an unanswered question. One of the most essential observables needed in its modelling are the metallicity distribution and the trends of the alpha elements as…

Astrophysics of Galaxies · Physics 2014-12-10 N. Ryde , M. Schultheis

The Bulge is the least understood major stellar population of the Milky Way. Most of what we know about the formation and evolution of the Bulge comes from bright giant stars. The underlying assumption that giants represent all the stars,…

We present the metallicity results from the ARGOS spectroscopic survey of the Galactic bulge. Our aim is to understand the formation of the Galactic bulge: did it form via mergers, as expected from Lambda CDM theory, or from disk…

Astrophysics of Galaxies · Physics 2015-06-12 M. Ness , K. Freeman , E. Athanassoula , E. Wylie de Boer , J. Bland Hawthorn , M. Asplund , G. F. Lewis , D. Yong , R. R. Lane , L. L. Kiss

We study the star-formation history of the Galactic bulge, as derived from the age distribution of the central stars of planetary nebulae that belong to this stellar population. The high resolution imaging and spectroscopic observations of…

Solar and Stellar Astrophysics · Physics 2014-07-02 K. Gesicki , A. A. Zijlstra , M. Hajduk , C. Szyszka

The structure and kinematics of the old component of the Galactic bulge are still a matter of debate. The bulk of the bulge as traced by red clump stars includes two main components, which are usually identified as the metal-rich and…