scholarly journals Gamma-rays from massive stars in Cygnus and Orion

2003 ◽  
Vol 212 ◽  
pp. 706-709 ◽  
Author(s):  
Roland Diehl ◽  
Karsten Kretschmer ◽  
Stefan Plüschke ◽  
Miguel Cerviño ◽  
Dieter H. Hartmann
Keyword(s):  
Gamma Rays ◽  
Massive Stars ◽  
Line Emission ◽  
Star Clusters ◽  
Young Star ◽  
Synthesis Methods ◽  
Population Synthesis ◽  
Supernova Explosions ◽  
Γ Ray ◽  
Young Star Clusters

Radioactive 26Al, ejected by massive stars through winds and supernova explosions, leads to γ-ray line emission that can serve as a probe of the interstellar environment in and near young star clusters. The ~ 1 Myr decay time of 26Al is long enough to allow transport over significant distances, which can cause substantial angular offsets between γ-ray emission and cluster stars. Details of such offsets are determined by the morphology of the ISM. We discuss observations in Cygnus and Orion, and models based on population synthesis methods.

scholarly journals Diffuse galactic Gamma-rays from star clusters

2020 ◽  
Vol 499 (1) ◽  
pp. L1-L5
Author(s):  
Biman B Nath ◽  
David Eichler
Keyword(s):  
Gamma Rays ◽  
Surface Brightness ◽  
Star Clusters ◽  
Young Star ◽  
Significant Fraction ◽  
Galactic Emission ◽  
Γ Ray ◽  
Young Star Clusters

ABSTRACT We demonstrate that young star clusters have a γ-ray surface brightness comparable to that of the diffuse Galactic emission (DGE), and estimate that their sky coverage in the direction of the inner Galaxy exceeds unity. We therefore suggest that they comprise a significant fraction of the DGE.

scholarly journals Hyperfast pulsars as the remnants of massive stars ejected from young star clusters

2008 ◽  
Vol 385 (2) ◽  
pp. 929-938 ◽  
Author(s):  
Vasilii V. Gvaramadze ◽  
Alessia Gualandris ◽  
Simon Portegies Zwart
Keyword(s):  
Massive Stars ◽  
Star Clusters ◽  
Young Star ◽  
Young Star Clusters

scholarly journals Ionizing the intergalactic medium by star clusters: the first empirical evidence

2019 ◽  
Vol 491 (1) ◽  
pp. 1093-1103 ◽  
Author(s):  
E Vanzella ◽  
G B Caminha ◽  
F Calura ◽  
G Cupani ◽  
M Meneghetti ◽  
...  
Keyword(s):  
Massive Stars ◽  
Star Clusters ◽  
Young Star ◽  
Ultraviolet Emission ◽  
Stellar Feedback ◽  
Stellar Component ◽  
High Ionization ◽  
Exceptional Object ◽  
Young Star Clusters ◽  
Work Supports

ABSTRACT We present a VLT/X-Shooter spectroscopy of the Lyman continuum (LyC) emitting galaxy Ion2 at z = 3.2121 and compare it to that of the recently discovered strongly lensed LyC emitter at z = 2.37, known as the Sunburst arc. Three main results emerge from the X-Shooter spectrum: (a) the Ly α has three distinct peaks with the central one at the systemic redshift, indicating a ionized tunnel through which both Ly α and LyC radiation escape; (b) the large O32 oxygen index ([O iii] λλ4959, 5007/[O ii] λλ3727, 3729) of $9.18_{-1.32}^{+1.82}$ is compatible to those measured in local (z ∼0.4) LyC leakers; (c) there are narrow nebular high-ionization metal lines with σv < 20 km s−1, which confirms the presence of young hot, massive stars. The He iiλ1640 appears broad, consistent with a young stellar component including Wolf–Rayet stars. Similarly, the Sunburst LyC emitter shows a triple-peaked Ly α profile and from VLT/MUSE spectroscopy the presence of spectral features arising from young hot and massive stars. The strong lensing magnification, (μ > 20), suggests that this exceptional object is a gravitationally bound star cluster observed at a cosmological distance, with a stellar mass M ≲ 107 M⊙ and an effective radius smaller than 20 pc. Intriguingly, sources like Sunburst but without lensing magnification might appear as Ion2-like galaxies, in which unresolved massive star clusters dominate the ultraviolet emission. This work supports the idea that dense young star clusters can contribute to the ionization of the IGM through holes created by stellar feedback.

scholarly journals Metallicity and X-ray luminosity variations in NGC 922

2020 ◽  
Vol 500 (1) ◽  
pp. 962-975
Author(s):  
K Kouroumpatzakis ◽  
A Zezas ◽  
A Wolter ◽  
A Fruscione ◽  
K Anastasopoulou ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Massive Stars ◽  
Star Clusters ◽  
Young Star ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Main Driver ◽  
Young Star Clusters

ABSTRACT We present a systematic study of the metallicity variations within the collisional ring galaxy NGC 922 based on long-slit optical spectroscopic observations. We find a metallicity difference between star-forming regions in the bulge and the ring, with metallicities ranging from almost solar to significantly sub-solar ($\rm {[12+\log (O/H)]\sim 8.2}$). We detect $\rm{He\,{\small I}}$ emission in all the studied regions of the bulge and the ring, indicating ionization from massive stars associated with recent (&lt;10 Myr) star formation, in agreement with the presence of very young star clusters. We find an anticorrelation between the X-ray luminosity and metallicity of the sub-galactic regions of NGC 922. The different regions have similar stellar population ages, leaving metallicity as the main driver of the anticorrelation. The dependence of the X-ray emission of the different regions in NGC 922 on metallicity is in agreement with similar studies of the integrated X-ray output of galaxies and predictions from X-ray binary population models.

scholarly journals Formation of massive binaries

2003 ◽  
Vol 212 ◽  
pp. 80-90 ◽  
Author(s):  
Hans Zinnecker
Keyword(s):  
Stellar Evolution ◽  
Massive Stars ◽  
Star Clusters ◽  
Young Star ◽  
Spectroscopic Binaries ◽  
Stellar Clusters ◽  
Multiple Systems ◽  
Short Period ◽  
Young Star Clusters ◽  
Runaway Stars

The formation of massive stars is one of the major unsolved problems in stellar astrophysics. However, only few if any of these are found as single stars, on average massive stars have more than one companion. Many of them are born in dense stellar clusters and several clusters have an excess of massive short-period spectroscopic binaries, with severe implication for binary-related stellar evolution including mergers, and also for the origin of massive runaway stars. The multiplicity of massive stars seems to increase with increasing primary mass and with increasing density of young star clusters. These observations suggest that massive binary and multiple systems originate mainly from dynamical gravitational interactions and accretion-induced protostellar collisions in dense clusters. If true, the binary properties of massive stars in less dense OB associations should be less extreme. This prediction should be tested by future observations. The paper reviews both the latest observations and theoretical ideas related to the origin of massive binaries. It concludes with a speculation on how the binary properties might change with metallicity (e.g., LMC/SMC).

scholarly journals Propagation of star formation at sub-kiloparsec scales

2019 ◽  
Vol 488 (3) ◽  
pp. 3045-3054
Author(s):  
A S Gusev ◽  
E V Shimanovskaya
Keyword(s):  
Star Formation ◽  
Spatial Scales ◽  
Dominant Role ◽  
Star Clusters ◽  
Young Star ◽  
H Ii Regions ◽  
Supernova Explosions ◽  
Stellar Associations ◽  
Young Star Clusters

ABSTRACT We study the propagation of star formation based on the investigation of the separation of young star clusters from H ii regions nearest to them. The relation between the separation and U − B colour index (or age) of a star cluster was found. The average age of star clusters increases with the separation as the 1.0–1.2 power in the separation range from 40 to 200 pc and as the 0.4–0.9 power in the range of 100–500 pc in the galaxies with symmetric morphology. The galaxies with distorted asymmetric disc structure show more complex and steeper (power >1.2 at separations from 40 to 500 pc) dependence between the age and the separation. Our results confirm the findings of previous studies on the dominant role of turbulence in propagation of the star formation process on spatial scales up to 500 pc and on time-scales up to 300 Myr. On a smaller scale (≤100 pc), other physical processes, such as stellar winds and supernova explosions, play an important role along with turbulence. On the scale of stellar associations (100–200 pc and smaller), the velocity of star formation propagation is almost constant and it has a typical value of a few km s−1.

The Wolf-Rayet Stars in 30 Doradus

1982 ◽  
Vol 99 ◽  
pp. 545-549 ◽  
Author(s):  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Chemical Composition ◽  
Massive Star ◽  
Massive Stars ◽  
Star Clusters ◽  
Hii Regions ◽  
Young Star ◽  
Hii Region ◽  
Formation And Evolution ◽  
Young Star Clusters

Giant HII regions as sites of massive star formation.Giant HII regions are the brightest extragalactic emission line objects that can be studied in detail. With diameters of several hundreds of parsecs, these nebulae can be easily resolved out to distances of a few Mpc. Typically 100 or more 0 stars are required to account for the observed ionization of the nebular gas and this implies that the cores of giant HII regions contain populous young star clusters. The stars in these clusters have essentially the same age and chemical composition. Thus, giant HII region cores provide excellent sites where theories of the formation and evolution of massive stars and, in particular, of Wolf-Rayet (WR) stars can be tested.

Black Hole dynamics in Young Star Clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 490-493
Author(s):  
Sara Rastello ◽  
Ugo N. di Carlo ◽  
Michela Mapelli ◽  
Nicola Giacobbo ◽  
Alessandro Ballone
Keyword(s):  
Black Hole ◽  
Binary Star ◽  
Star Clusters ◽  
Young Star ◽  
Population Synthesis ◽  
Massive Black Hole ◽  
Binary Black Holes ◽  
Black Hole Binaries ◽  
Low Mass ◽  
Young Star Clusters

AbstractYoung star clusters are a promising environment for forming binary black holes. Such binaries may form dynamically or via binary star evolution or through the interplay of these two channels. To study these formation pathways, we have performed high precision direct N-body simulations of low-mass (M < 1000 M⊙) young star clusters. The simulations were carried out with the code Nbody6++GPU coupled with the population synthesis code MOBSE. Our results highlight the importance of dynamics to form massive black hole binaries even in low-mass young star clusters.

scholarly journals Dynamics of black hole–neutron star binaries in young star clusters

2020 ◽  
Vol 497 (2) ◽  
pp. 1563-1570 ◽  
Author(s):  
Sara Rastello ◽  
Michela Mapelli ◽  
Ugo N Di Carlo ◽  
Nicola Giacobbo ◽  
Filippo Santoliquido ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Total Mass ◽  
Star Clusters ◽  
Cosmic Time ◽  
Young Star ◽  
Star Cluster ◽  
Population Synthesis ◽  
Compact Binaries ◽  
Young Star Clusters

ABSTRACT Young star clusters are likely the most common birthplace of massive stars across cosmic time and influence the formation of compact binaries in several ways. Here, we simulate the formation of black hole–neutron star binaries (BHNSs) in young star clusters, by means of the binary population synthesis code MOBSE interfaced with the N-body code NBODY6++GPU. BHNSs formed in young star clusters (dynamical BHNSs) are significantly more massive than BHNSs formed from isolated binaries (isolated BHNSs): ∼40 per cent of the dynamical BHNS mergers have a total mass of &gt;15 M⊙, while only ∼0.01 per cent of the isolated BHNS mergers have mass in excess of this value. Hence, our models strongly support a dynamical formation scenario for GW190814, given its total mass of ∼26 M⊙, if this event is a BHNS merger. All our dynamical BHNSs are ejected from their parent star cluster before they reach coalescence. Thus, a significant fraction of BHNS mergers occurring in the field might have originated in a young star cluster. The mass spectrum of BHNS mergers from gravitational-wave detections will provide a clue to differentiate between dynamical and isolated formation of BHNSs.

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