scholarly journals Analysis of enrichment histories for elements and two modes of star formation during the early evolution of Milky Way

2014 ◽  
Author(s):  
Shimako Yamada ◽  
Takuma Suda ◽  
Yutaka Komiya ◽  
Wako Aoki ◽  
Masayuki Y Fujimoto
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Early Evolution

scholarly journals Contribution of globular clusters to halos

2015 ◽  
Vol 12 (S316) ◽  
pp. 287-293
Author(s):  
Angela Bragaglia
Keyword(s):  
Star Formation ◽  
Formation Mechanism ◽  
Globular Clusters ◽  
Massive Star ◽  
Milky Way ◽  
Star Clusters ◽  
Early Evolution ◽  
Light Elements ◽  
Halo Stars ◽  
Chemical Signatures

AbstractThe contribution of massive star clusters to their hosting halo dramatically depends on their formation mechanism and their early evolution. Massive globular clusters in the Milky Way (and in other galaxies) have been shown to display peculiar chemical patterns (light-elements correlations and anti-correlations) indicative of a complex star formation, confirmed by photometric evidence (spread or split sequences). I use these chemical signatures to try to understand what is the fraction of halo stars originally born in globular clusters.

scholarly journals Are ultra-diffuse galaxies Milky Way-sized?

2020 ◽  
Vol 633 ◽  
pp. L3 ◽  
Author(s):  
Nushkia Chamba ◽  
Ignacio Trujillo ◽  
Johan H. Knapen
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Size Range ◽  
Mass Density ◽  
Effective Radius ◽  
Density Profiles ◽  
Gas Density ◽  
Undesirable Consequence ◽  
Definition Of ◽  
Density Threshold

Now almost 70 years since its introduction, the effective or half-light radius has become a very popular choice for characterising galaxy size. However, the effective radius measures the concentration of light within galaxies and thus does not capture our intuitive definition of size which is related to the edge or boundary of objects. For this reason, we aim to demonstrate the undesirable consequence of using the effective radius to draw conclusions about the nature of faint ultra-diffuse galaxies (UDGs) when compared to dwarfs and Milky Way-like galaxies. Instead of the effective radius, we use a measure of galaxy size based on the location of the gas density threshold required for star formation. Compared to the effective radius, this physically motivated definition places the sizes much closer to the boundary of a galaxy. Therefore, considering the sizes and stellar mass density profiles of UDGs and regular dwarfs, we find that the UDGs have sizes that are within the size range of dwarfs. We also show that currently known UDGs do not have sizes comparable to Milky Way-like objects. We find that, on average, UDGs are ten times smaller in extension than Milky Way-like galaxies. These results show that the use of size estimators sensitive to the concentration of light can lead to misleading results.

scholarly journals On the early evolution of Local Group dwarf galaxy types: star formation and supernova feedback

2018 ◽  
Vol 479 (2) ◽  
pp. 1514-1527 ◽  
Author(s):  
José R Bermejo-Climent ◽  
Giuseppina Battaglia ◽  
Carme Gallart ◽  
Arianna Di Cintio ◽  
Chris B Brook ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxy ◽  
Early Evolution ◽  
Supernova Feedback

scholarly journals Central Molecular Zone of the Milky Way: Star Formation in an extreme Environment

2015 ◽  
Vol 11 (S315) ◽  
pp. 163-166
Author(s):  
Jens Kauffmann
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Spatial Scales ◽  
Extreme Environment ◽  
Average Density ◽  
High Mass ◽  
Density Structure ◽  
Star Formation Activity ◽  
Order Of Magnitude ◽  
Sgr A

AbstractThe Central Molecular Zone (CMZ; inner ~100 pc) hosts some of the most dense and massive molecular clouds of the Milky Way. These clouds might serve as local templates for dense clouds seen in nearby starburst galaxies or in the early universe. The clouds have a striking feature: they form stars at a very slow pace, considering their mass and high average density. Here we use interferometer data from ALMA and the SMA to show that this slow star formation is a consequence of the cloud density structure: CMZ clouds have a very flat density structure. They might, for example, exceed the average density of the Orion A molecular cloud by an order of magnitude on spatial scales ~5 pc, but CMZ “cores” of ~0.1 pc radius have masses and densities lower than what is found in the Orion KL region. This absence of highest–density gas probably explains the suppression of star formation. The clouds are relatively turbulent, and ALMA observations of H2CO and SiO indicate that the turbulence is induced by high–velocity shocks. We speculate that these shocks might prevent the formation of high–mass cores. It has been argued that the state of CMZ clouds depends on their position along the orbit around Sgr A*. Our incomplete data indicate no evolution in the density structure, and only a modest evolution in star formation activity per unit mass.

scholarly journals Combination of CN(1-0), HCN(1-0), and HNC(1-0): A possible indicator for a high-mass star formation sequence in the Milky Way

2015 ◽  
Vol 576 ◽  
pp. A131 ◽  
Author(s):  
X. H. Han ◽  
J. J. Zhou ◽  
J. Z. Wang ◽  
J. Esimbek ◽  
J. S. Zhang ◽  
...  
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
High Mass ◽  
Mass Star

scholarly journals Observation of triggering in the Milky Way

2006 ◽  
Vol 2 (S237) ◽  
pp. 212-216 ◽  
Author(s):  
L. Deharveng ◽  
A. Zavagno ◽  
B. Lefloch ◽  
J. Caplan ◽  
M. Pomarès
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Milky Way ◽  
Turbulent Medium ◽  
Massive Star Formation ◽  
Collapse Process

AbstractWe show how the expansion of classical Galactic Hiiregions can trigger massive-star formation via the collect & collapse process. We give examples of this process at work. We suggest that it also works in a turbulent medium.

Perseus arm - a new perspective on star formation and spiral structure in our home galaxy

2021 ◽  
Author(s):  
M Wienen ◽  
C M Brunt ◽  
C L Dobbs ◽  
D Colombo
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Milky Way ◽  
Velocity Structure ◽  
Data Cube ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Linear Scale ◽  
Perseus Arm ◽  
Spiral Arm

Abstract Expansion of (sub)millimetre capabilities to high angular resolution offered with interferometers allows to resolve giant molecular clouds (GMCs) in nearby galaxies. This enables us to place the Milky Way in the context of other galaxies to advance our understanding of star formation in our own Galaxy. We thus remap 12CO (1 - 0) data along the Perseus spiral arm in the outer Milky Way to a fixed physical resolution and present the first spiral arm data cube at a common distance as it would be seen by an observer outside the Milky Way. To achieve this goal we calibrated the longitude-velocity structure of 12CO gas of the outer Perseus arm based on trigonometric distances and maser velocities provided by the BeSSeL survey. The molecular gas data were convolved to the same spatial resolution along the whole spiral arm and regridded on to a linear scale map with the coordinate system transformed to the spiral arm reference frame. We determined the width of the Perseus spiral arm to be 7.8 ± 0.2 km s−1 around the kinematic arm centre. To study the large scale structure we derived the 12CO gas mass surface density distribution of velocities shifted to the kinematic arm centre and arm length. This yields a variation of the gas mass surface density along the arm length and a compression of molecular gas mass at linear scale. We determined a thickness of ∼63 pc on average for the Perseus spiral arm and a centroid of the molecular layer of 8.7 pc.

Something about Red Supergiants

2019 ◽  
Vol 14 (S353) ◽  
pp. 24-25
Author(s):  
Maria Messineo
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Galactic Disk ◽  
Red Supergiants ◽  
Massive Clusters

AbstractI would like to present an overview of red supergiants (RSGs) in the Milky Way. There are only about 1400 objects listed as RSGs in the spectroscopic catalog by Skiff (2014); moreover, we are not sure yet about how they formed and where they formed. Indeed, most of them are strangely found in isolation, while extraordinary massive clusters of RSGs are observed at the near-end of the Galactic Bar. This intriguing overdensity poses some questions about the continuity of star formation in the Galactic Disk.

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