scholarly journals Unveiling the Secrets of the Galactic bulge through stellar abundances in the near-IR: a VLT/Crires project

2008 ◽  
Vol 4 (S254) ◽  
pp. 159-164
Author(s):  
Nils Ryde
Keyword(s):  
Milky Way ◽  
Line Of Sight ◽  
Galactic Bulge ◽  
Stellar Abundances ◽  
Preliminary Results ◽  
Elemental Abundances ◽  
Near Ir ◽  
Visual Extinction ◽  
Formation And Evolution

AbstractThe formation and evolution of the Milky Way bulge can be constrained by studying elemental abundances of bulge stars. Due to the large and variable visual extinction in the line-of-sight towards the bulge, an analysis in the near-IR is preferred. Here, I will present some preliminary results of an on-going project in which elemental abundances, especially those of the C, N, and O elements, of bulge stars are investigated by analysing CRIRES spectra observed with the VLT.

scholarly journals CNO abundances in the Galactic bulge

2009 ◽  
Vol 5 (S265) ◽  
pp. 285-288
Author(s):  
Nils A. E. Ryde
Keyword(s):  
Ir Spectra ◽  
Milky Way ◽  
Recent Analysis ◽  
Line Of Sight ◽  
Galactic Bulge ◽  
Elemental Abundances ◽  
Near Ir ◽  
Visual Extinction ◽  
Formation And Evolution ◽  
Cno Abundances

AbstractThe carbon, nitrogen, and oxygen abundances and trends in the bulge are discussed in the context of our recent analysis of these elements in an on-going project based on near-IR spectra (Ryde et al. 2009). We obtained these using the CRIRES spectrometer on the VLT. The formation and evolution of the Milky Way bulge can be constrained by studying elemental abundances of bulge stars. Due to the large and variable visual extinction in the line-of-sight towards the bulge, an analysis in the near-IR is preferred.

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.

scholarly journals Globular Clusters in the Galactic Bulge

2016 ◽  
Vol 33 ◽  
Author(s):  
E. Bica ◽  
S. Ortolani ◽  
B. Barbuy
Keyword(s):  
Globular Clusters ◽  
Deep Understanding ◽  
Selective Absorption ◽  
Galactic Bulge ◽  
Chemical Abundances ◽  
Elemental Abundances ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Future Work ◽  
Shed Light

AbstractA view of the Galactic bulge by means of their globular clusters is fundamental for a deep understanding of its formation and evolution. Connections between the globular cluster and field star properties in terms of kinematics, orbits, chemical abundances, and ages should shed light on different stellar population components. Based on spatial distribution and metallicity, we define a probable best list of bulge clusters, containing 43 entries. Future work on newly discovered objects, mostly from the VVV survey, is suggested. These candidates might alleviate the issue of missing clusters on the far side of the bulge. We discuss the reddening law affecting the cluster distances towards the centre of the Galaxy, and conclude that the most suitable total-to-selective absorption value appears to be RV=3.2, in agreement with recent analyses. An update of elemental abundances for bulge clusters is provided.

scholarly journals Stellar variability in the VVV survey: overview and first results

2013 ◽  
Vol 9 (S301) ◽  
pp. 395-396
Author(s):  
M. Catelan ◽  
D. Minniti ◽  
P. W. Lucas ◽  
I. Dékány ◽  
R. K. Saito ◽  
...  
Keyword(s):  
Time Series ◽  
Main Part ◽  
Near Infrared ◽  
Milky Way ◽  
Galactic Bulge ◽  
Near Ir ◽  
Public Survey ◽  
First Results

AbstractThe Vista Variables in the Vía Láctea (VVV) ESO Public Survey is an ongoing time-series, near-infrared (IR) survey of the Galactic bulge and an adjacent portion of the inner disk, covering 562 square degrees of the sky, using ESO's VISTA telescope. The survey has provided superb multi-color photometry in 5 broadband filters (Z, Y, J, H, and Ks), leading to the best map of the inner Milky Way ever obtained, particularly in the near-IR. The main part of the survey, which is focused on the variability in the Ks-band, is currently underway, with bulge fields observed between 34 and 73 times, and disk fields between 34 and 36 times. When the survey is complete, bulge (disk) fields will have been observed up to a total of 100 (60) times, providing unprecedented depth and time coverage in the near-IR. Here we provide a first overview of stellar variability in the VVV data.

scholarly journals Detailed near-IR stellar abundances of red giants in the Inner Bulge and Galactic Center

2017 ◽  
Vol 13 (S334) ◽  
pp. 82-85
Author(s):  
N. Ryde ◽  
R. M. Rich ◽  
B. Thorsbro ◽  
M. Schultheis ◽  
T. K. Fritz ◽  
...  
Keyword(s):  
Stellar Population ◽  
Galactic Center ◽  
Galactic Plane ◽  
Star Cluster ◽  
High Dispersion ◽  
Red Giants ◽  
Galactic Bulge ◽  
Stellar Abundances ◽  
Near Ir ◽  
K Band

AbstractOwing to their extreme crowding and high and variable extinction, stars in the Galactic Bulge, within ±2° of the Galactic plane, and especially those in the Nuclear Star Cluster, have only rarely been targeted for an analyses of their detailed abundances. There is also some disagreement about the high end of the abundance scale for these stars. It is now possible to obtain high dispersion, high S/N spectra in the infrared K band (~2.0 − 2.4 µm) for these giants; we report our progress at Keck and VLT in using these spectra to infer the composition of this stellar population.

scholarly journals Modelling the Galactic Bar using Red Clump Stars

1996 ◽  
Vol 157 ◽  
pp. 545-548 ◽  
Author(s):  
K. Z. Stanek ◽  
M. Mateo ◽  
A. Udalski ◽  
M. Szymański ◽  
J. Kałuzny ◽  
...  
Keyword(s):  
Line Of Sight ◽  
Galactic Bulge ◽  
Preliminary Results ◽  
Gravitational Microlensing ◽  
Luminosity Functions ◽  
Red Clump ◽  
Additional Constraints ◽  
Galactic Longitude

AbstractThe color-magnitude diagrams of ~ 1 × 106 stars obtained for 19 fields towards the Galactic bulge with the OGLE project reveal a well-defined population of bulge red clump stars. We found that the distributions of the extinction-adjusted apparent magnitudes of red clump stars in fields lying at ι = ±5° in galactic longitude differ by ∼ 0.4 mag. A plausible explanation of this observed difference in the luminosity distribution is that the Galactic bulge is a triaxial structure, or a bar, which is inclined to the line of sight by no more than 45°. The part of the bar at the positive galactic longitude is closer to us. Work is now under way to model the Galactic bar by fitting the observed luminosity functions in the red clump region for various fields. Preliminary results indicate that the angle of the inclination of the bar to the line of sight can be as small as ∼ 20°. Gravitational microlensing can provide us with additional constraints on the structure of the Galactic bar.

scholarly journals Spectral Synthesis of the Integrated Spectrum of the Galactic Bulge

1996 ◽  
Vol 171 ◽  
pp. 361-361
Author(s):  
Sonya Delisle ◽  
Eduardo Hardy
Keyword(s):  
Globular Cluster ◽  
Spectral Synthesis ◽  
Line Of Sight ◽  
Population Synthesis ◽  
Galactic Bulge ◽  
Stellar Spectra ◽  
Optimization Program ◽  
Preliminary Results ◽  
Solar Metallicity

We present preliminary results of the population synthesis of the Galactic Bulge using different techniques. The observations, taken with CTIO's 4m CS, cover the range 3600Å to 10000Å. The integrated spectrum includes light from stars in the line-of-sight. For the synthesis, we used first a program that we developed (Couture & Hardy (1993), and Hardy et al. (1994)) along with three libraries, one of composite population spectra, (Jablonka et al. (1990) and Bica (1988)), one of stellar spectra (Pickles (1985)), and one of equivalent widths measured on the integrated spectra of coeval populations (Bica and Alloin (1986a), (1986b) and (1987)). Results obtained with the spectra were inconclusive. With the equivalent widths, we found indication of the presence of a young and rich population (1 Myr and [Z/Z⊙]=+0.3), but no old population or poor globular cluster-like population. Further tests are needed to evaluate the extent of the contamination from disk giants and its impact on the synthesis results. We also used Bica and Alloin's optimization program (Bica (1988)) with their library of equivalent witdhs. The contributions are spread over many groups but mainly intermediate-age, above-solar metallicity groups and old and poor groups. In all cases, no old metal-rich population was detected.

scholarly journals The Galactic bulge: a review

2007 ◽  
Vol 3 (S245) ◽  
pp. 323-332 ◽  
Author(s):  
Dante Minniti ◽  
Manuela Zoccali
Keyword(s):  
Chemical Composition ◽  
Central Region ◽  
Milky Way ◽  
Galactic Center ◽  
Current Understanding ◽  
Ir Detectors ◽  
Individual Stars ◽  
Near Ir ◽  
Great Progress ◽  
Formation And Evolution

AbstractThe Milky Way is the only galaxy for which we can resolve individual stars at all evolutionary phases, from the Galactic center to the outskirt. The last decade, thanks to the advent of near IR detectors and 8 meter class telescopes, has seen a great progress in the understanding of the Milky Way central region: the bulge. Here we review the most recent results regarding the bulge structure, age, kinematics and chemical composition. These results have profound implications for the formation and evolution of the Milky Way and of galaxies in general. This paper provides a summary on our current understanding of the Milky Way bulge, intended mainly for workers on other fields.

scholarly journals Fundamental Properties of a Large, Unbiased Sample of Massive, Young, Embedded Star Clusters in the Milky Way

2015 ◽  
Vol 12 (S316) ◽  
pp. 127-128
Author(s):  
Yigit Dallilar ◽  
Peter Barnes ◽  
Elizabeth Lada ◽  
Stuart Ryder
Keyword(s):  
Milky Way ◽  
Line Of Sight ◽  
Molecular Gas ◽  
Infrared Photometry ◽  
Gas Emission ◽  
Infrared Observations ◽  
Fundamental Properties ◽  
Near Ir ◽  
Medium Mass ◽  
Infrared Extinction

AbstractIn this project, we focus on the analysis of infrared observations of the clumps defined with the Galactic Census of High- and Medium-mass Protostars (ChaMP) (Barneset al.2011). We derive line of sight infrared extinction values, star counts and protostar candidates around the molecular gas emission obtained with the Mopra telescope. Then, we examine the correlation between radio and infrared properties of the clumps. For this stage of the project, we use the Vela-Carina and 2MASS catalogs to obtain a preliminary understanding of the final results. For the later stages, we will extract infrared photometry from our deep AAT near-IR andSpitzer3.6 and 4.5 μm images. With the final deep photometry results, we will compile the properties of individual clusters.

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