scholarly journals Massive infrared clusters in the Milky Way

2016 ◽  
Vol 12 (S329) ◽  
pp. 263-270
Author(s):  
André-Nicolas Chené ◽  
Sebastian Ramírez Alegría ◽  
Jordanka Borissova ◽  
Anthony Hervé ◽  
Fabrice Martins ◽  
...  
Keyword(s):  
Near Infrared ◽  
Milky Way ◽  
Galactic Center ◽  
Massive Stars ◽  
Star Clusters ◽  
Infrared Observations ◽  
Fundamental Parameters ◽  
Dust Extinction ◽  
Young Clusters ◽  
Massive Clusters

AbstractOur position in the Milky Way (MW) is both a blessing and a curse. We are nearby to many star clusters, but the dust that is a product of their very existence obscures them. Also, many massive young clusters are expected to be located near, or across the Galactic Center, where the dust extinction is extreme (AV > 15 mag) and can be better penetrated by infrared photons. This paper reviews the discoveries and the study of new MW massive stars and massive clusters made possible by near infrared observations that are part of the VISTA Variables in the Vía Láctea (VVV) survey. It discusses what the studies of their fundamental parameters have taught us.

scholarly journals Massive Stars in the Galactic Center

2007 ◽  
Vol 3 (S250) ◽  
pp. 257-264
Author(s):  
F. Martins ◽  
D. J. Hillier ◽  
R. Genzel ◽  
F. Eisenhauer ◽  
T. Ott ◽  
...  
Keyword(s):  
Massive Star ◽  
Near Infrared ◽  
Galactic Center ◽  
Massive Stars ◽  
Evolutionary Status ◽  
Infrared Spectral Range ◽  
Different Types ◽  
Infrared Spectral ◽  
Observational Techniques ◽  
Massive Clusters

AbstractWe present results of two studies aiming at better understanding the properties of massive stars in the Galactic Center. We focus on the youngest and oldest of the three massive clusters harboring this region, namely the Arches and central cluster. We show that the development of powerful observational techniques in the near infrared spectral range (mainly 3D spectroscopy) allows to uncover the entire massive star population in these clusters. Using CMFGEN models, we derive the classical stellar and wind properties of 46 stars, as well as their surface abundances. The latter allow us to investigate in detail their evolutionary status and to identify evolutionary sequences between different types of stars. We thus constrain stellar evolution in the upper part of the HR diagram.

scholarly journals The accreted nuclear clusters of the Milky Way

2020 ◽  
Vol 500 (2) ◽  
pp. 2514-2524
Author(s):  
Joel Pfeffer ◽  
Carmela Lardo ◽  
Nate Bastian ◽  
Sara Saracino ◽  
Sebastian Kamann
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
Host Galaxy ◽  
The Galaxy ◽  
Nuclear Clusters ◽  
The Common ◽  
Massive Clusters ◽  
Peculiar Case

ABSTRACT A number of the massive clusters in the halo, bulge, and disc of the Galaxy are not genuine globular clusters (GCs) but instead are different beasts altogether. They are the remnant nuclear star clusters (NSCs) of ancient galaxies since accreted by the Milky Way. While some clusters are readily identifiable as NSCs and can be readily traced back to their host galaxy (e.g. M54 and the Sagittarius Dwarf galaxy), others have proven more elusive. Here, we combine a number of independent constraints, focusing on their internal abundances and overall kinematics, to find NSCs accreted by the Galaxy and trace them to their accretion event. We find that the true NSCs accreted by the Galaxy are: M54 from the Sagittarius Dwarf, ω Centari from Gaia-Enceladus/Sausage, NGC 6273 from Kraken, and (potentially) NGC 6934 from the Helmi Streams. These NSCs are prime candidates for searches of intermediate-mass black holes (BHs) within star clusters, given the common occurrence of galaxies hosting both NSCs and central massive BHs. No NSC appears to be associated with Sequoia or other minor accretion events. Other claimed NSCs are shown not to be such. We also discuss the peculiar case of Terzan 5, which may represent a unique case of a cluster–cluster merger.

scholarly journals The origin of very massive stars around NGC 3603

2019 ◽  
Vol 625 ◽  
pp. L2 ◽  
Author(s):  
V. M. Kalari ◽  
J. S. Vink ◽  
W. J. de Wit ◽  
N. J. Bastian ◽  
R. A. Méndez
Keyword(s):  
Near Infrared ◽  
Milky Way ◽  
Massive Stars ◽  
Mass Function ◽  
Initial Mass Function ◽  
Future Data ◽  
Solar Type ◽  
Stellar Initial Mass Function ◽  
The Universe ◽  
Shed Light

The formation mechanism of the most massive stars in the Universe remains an unsolved problem. Are they able to form in relative isolation in a manner similar to the formation of solar-type stars, or do they necessarily require a clustered environment? In order to shed light on this important question, we study the origin of two very massive stars (VMS): the O2.5If*/WN6 star RFS7 (∼100 M⊙), and the O3.5If* star RFS8 (∼70 M⊙), found within ∼53 and 58 pc, respectively, of the Galactic massive young cluster NGC 3603, using Gaia data. The star RFS7 is found to exhibit motions resembling a runaway star from NGC 3603. This is now the most massive runaway star candidate known in the Milky Way. Although RFS8 also appears to move away from the cluster core, it has proper-motion values that appear inconsistent with being a runaway from NGC 3603 at the 3σ level (but with substantial uncertainties due to distance and age). Furthermore, no evidence for a bow-shock or a cluster was found surrounding RFS8 from available near-infrared photometry. In summary, whilst RFS7 is likely a runaway star from NGC 3603, making it the first VMS runaway in the Milky Way, RFS8 is an extremely young (∼2 Myr) VMS, which might also be a runaway, but this would need to be established from future spectroscopic and astrometric observations, as well as precise distances. If RFS 8 was still not found to meet the criteria for being a runaway from NGC 3603 from such future data, this would have important ramifications for current theories of massive star formation, as well as the way the stellar initial mass function is sampled.

scholarly journals The influence of feedback from massive stars on the formation and emergence of massive clusters

2015 ◽  
Vol 12 (S316) ◽  
pp. 177-183
Author(s):  
James E. Dale
Keyword(s):  
Large Scale ◽  
Massive Star ◽  
Massive Stars ◽  
Cluster Structure ◽  
Star Clusters ◽  
Stellar Feedback ◽  
Making Sense ◽  
Formation Efficiency ◽  
Massive Clusters ◽  
Made In

AbstractMassive star clusters are of fundamental importance both observationally, since they are visible at such great distances, and theoretically, because of their influence on the large–scale ISM. Understanding stellar feedback is a prerequisite for making sense of their formation and early evolution, since feedback influences cluster structure, star formation efficiency, and sets the timescales on which clusters emerge from their parent clouds to become optically visible. I review the progress made in understanding these issues from a numerical perspective.

scholarly journals Radio observations of Galactic Center massive stars

2003 ◽  
Vol 212 ◽  
pp. 497-504
Author(s):  
Cornelia C. Lang
Keyword(s):  
Near Infrared ◽  
Galactic Center ◽  
Stellar Winds ◽  
Radio Sources ◽  
Stellar Clusters ◽  
X Ray ◽  
Spatial Properties ◽  
Gc Clusters ◽  
Infrared Sources ◽  
Massive Clusters

High-resolution multi-frequency observations made with the VLA have revealed the presence of stellar winds in two of the three known massive stellar clusters at the Galactic Center (GC). At a distance of only 8.0 kpc, we are able to resolve radio sources associated with individual near-infrared sources known to be losing mass at high rates. Herein, I discuss the spectral and spatial properties of the radio sources and their near-infrared counterparts, their inferred mass-loss rates, variability and the prospects for detecting stellar winds sources in the Central Cluster, near the supermassive blackhole SgrA*. Such massive clusters as these three GC clusters have a profound impact on the interstellar medium, as evidenced by radio and X-ray observations of the surrounding regions.

scholarly journals Super star clusters in the Galactic Center as revealed by HST-NICMOS

1999 ◽  
Vol 193 ◽  
pp. 459-469
Author(s):  
Donald F. Figer ◽  
Sungsoo S. Kim ◽  
Mark Morris ◽  
Eugene Serabyn
Keyword(s):  
Main Sequence ◽  
Local Group ◽  
Galactic Center ◽  
Formation Rate ◽  
Star Clusters ◽  
Initial Mass Function ◽  
Stellar Content ◽  
Multiple Star ◽  
Super Star Clusters ◽  
Massive Clusters

The three massive clusters in the Galactic Center are not only the most massive young clusters in the Galaxy, but they harbor more Wolf-Rayet stars than any other starburst region in the Local Group. An understanding of their stellar content will be valuable for extending models to starburst regions in other galaxies. We present HST-NICMOS images, luminosity functions, and color-magnitude diagrams of two of these: the Quintuplet and Arches clusters. The images allow the detection of stars over 6 magnitudes fainter than ever before and reveal previously undetected multiple star systems. For the first time, we clearly identify the main sequence in the Quintuplet cluster, and we extend earlier detections of the main sequence in the Arches cluster to Minitial < 10 M⊙. We estimate that the Arches cluster has an initial mass function slope which is greater than the Salpeter value. Given their stellar content, the Galactic Center clusters provide both the best nearby examples of super star clusters and the best nearby locale in which to investigate WR phenomena in starburst galaxies and galactic nuclei. We discuss the content of the Galactic Center clusters, with a particular emphasis on how they compare to other massive clusters of the local group. We expect that many of the massive stars in the Galactic Center will soon evolve to become WR stars, and eventually become supernovae at a rate of ∼ 1 per 20 000 years for the next several Myr. We note that our preliminary N-body simulations suggest that such dense clusters are short-lived in the strong tidal field of the Galactic Center, consistent with the fact that no older dense clusters are seen in the central 50 pc. This implies a star formation rate of 5(10−3) M⊙ yr−1 in the Galactic Center.

scholarly journals Galactic structure from trigonometric parallaxes of star-forming regions

2012 ◽  
Vol 8 (S289) ◽  
pp. 188-193 ◽  
Author(s):  
Mark J. Reid
Keyword(s):  
Interstellar Dust ◽  
Milky Way ◽  
Galactic Center ◽  
Star Forming ◽  
Fundamental Parameters ◽  
Star Forming Regions ◽  
Long Baseline ◽  
The Galaxy ◽  
Trigonometric Parallaxes ◽  
3D Information

AbstractRecently, astrometric accuracy approaching ~ 10 μas has become routinely possible with Very Long Baseline Interferometry. Since, unlike at optical wavelengths, interstellar dust is transparent at radio wavelengths, parallaxes and proper motions can now be measured for massive young stars (with maser emission) across the Galaxy, enabling direct measurements of the spiral structure of the Milky Way. Fitting the full 3D position and velocity vectors to a simple model of the Galaxy yields extremely accurate values for its fundamental parameters, including the distance to the Galactic Center, R0=8.38 ± 0.18 kpc, and circular rotation at the Solar Circle, Θ0 = 243 ± 7 km s−1. The rotation curve of the Milky Way, based for the first time on ‘gold standard’ distances and complete 3D information, appears to be very flat.

scholarly journals Young Massive Clusters

2007 ◽  
Vol 3 (S250) ◽  
pp. 247-256 ◽  
Author(s):  
Donald F. Figer
Keyword(s):  
Stellar Evolution ◽  
Massive Stars ◽  
Stellar Clusters ◽  
Infrared Observations ◽  
The Past ◽  
The Galaxy ◽  
The Masses ◽  
Near Future ◽  
Massive Clusters

AbstractOver the past ten years, there has been a revolution in our understanding of massive young stellar clusters in the Galaxy. Initially, there were no known examples having masses >104, yet we now know that there are at least a half dozen such clusters in the Galaxy. In all but one case, the masses have been determined through infrared observations. Several had been identified as clusters long ago, but their massive natures were only recently determined. Presumably, we are just scratching the surface, and we might look forward to having statistically significant samples of coeval massive stars at all important stages of stellar evolution in the near future. I review the efforts that have led to this dramatic turn of events and the growing sample of young massive clusters in the Galaxy.

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