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 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 Comparisons between observational color-magnitude diagrams and synthetic cluster diagrams for young star clusters in the Magellanic Clouds

1984 ◽  
Vol 105 ◽  
pp. 83-87
Author(s):  
Stephen A. Becker ◽  
Grant J. Mathews ◽  
Wendee M. Brunish
Keyword(s):  
Stellar Evolution ◽  
Main Sequence ◽  
Star Clusters ◽  
Theoretical Models ◽  
Young Star ◽  
Asymptotic Giant Branch ◽  
Current Status ◽  
Large Numbers ◽  
Young Star Clusters ◽  
Convective Overshoot

Young star clusters (<3 × 108 yr) in the Maqellanic Clouds (MC) can be used to test the current status of the theory of stellar evolution as applied to intermediate and massive stars. The color-magnitude diagram of many young clusters in the MC shows, unlike the case of clusters in our Galaxy, large numbers of stars in both the main sequence and post main sequence evolutionary phases. Usina a arid of stellar evolution models, synthetic cluster H-R diagrams are constructed and compared to observed color-magnitude diagrams to determine the age, age spread, and composition for any given cluster. In addition, for those cases where the data is of high quality, detailed comparisons between theory and observation can provide a diagnostic of the accuracy of the stellar evolution models. Initial indications of these comparisons suggest that the theoretical models should be altered to include: a larger value for the mixing length parameter (α), a larger rate of mass loss during the asymptotic giant branch (AGB) phase, and possibly convective overshoot during the core burning phases.

scholarly journals Rapid mass segregation in young star clusters without substructure?

2010 ◽  
Vol 6 (S271) ◽  
pp. 389-390
Author(s):  
C. Olczak ◽  
R. Spurzem ◽  
Th. Henning
Keyword(s):  
Initial Conditions ◽  
Star Clusters ◽  
Building Blocks ◽  
Young Star ◽  
Subsequent Formation ◽  
Multiple Systems ◽  
Mass Segregation ◽  
New Generation ◽  
The Impact ◽  
Young Star Clusters

AbstractThe young star clusters we observe today are the building blocks of a new generation of stars and planets in our Galaxy and beyond. Despite their fundamental role we still lack knowledge about the initial conditions under which star clusters form and the impact of these often harsh environments on the formation and evolution of their stellar and substellar members.We present recent results showing that mass segregation in realistic models of young star clusters occurs very quickly for subvirial spherical systems without substructure. This finding is a critical step to resolve the controversial debate on mass segregation in young star clusters and provides strong constraints on their initial conditions. The rapid concentration of massive stars is usually associated with strong gravitational interactions early on during cluster evolution and the subsequent formation of multiple systems and ejection of stars.

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 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.

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.

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