High-velocity stars from decay of small stellar systems

Kiseleva, L. G.; Colin, J.; Dauphole, B.; Eggleton, P. P.

doi:10.1046/j.1365-8711.1998.02043.x

Cited by 9 publications

(12 citation statements)

References 23 publications

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“…Also Delgado-Donate et al (2003) simulate the combined effects of competitive accretion and close dynamical interactions between individual protostars in detail. With respect to pairing statistics, escape speeds, and binary properties, they corroborate the results of pure point-mass calculations (Sterzik & Durisen 1995, 2003aKiseleva et al 1998a;Rubinov et al 2002) that neglect the effects of remnant molecular gas and disk accretion. By focusing on the stellar dynamical effects alone, the point-mass treatments provide predictions with highest statistical significance.…”

Section: Stage D: Dynamical Interactionssupporting

confidence: 74%

How do binary separations depend on cloud initial conditions?

Sterzik

Durisen

Zinnecker

2003

A&A

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Abstract.We explore the consequences of a star formation scenario in which the isothermal collapse of a rotating, star-forming core is followed by prompt fragmentation into a cluster containing a small number (N < ∼ 10) of protostars and/or substellar objects. The subsequent evolution of the cluster is assumed to be dominated by dynamical interactions among cluster members, and this establishes the final properties of the binary and multiple systems. The characteristic scale of the fragmenting core is determined by the cloud initial conditions (such as temperature, angular momentum and mass), and we are able to relate the separation distributions of the final binary population to the properties of the star-forming core. Because the fragmentation scale immediately after the isothermal collapse is typically a factor of 3−10 too large, we conjecture that fragmentation into small clusters followed by dynamical evolution is required to account for the observed binary separation distributions. Differences in the environmental properties of the cores are expected to imprint differences on the characteristic dimensions of the binary systems they form. Recent observations of hierarchical systems, differences in binary characteristics among star forming regions and systematic variations in binary properties with primary mass can be interpreted in the context of this scenario.

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Section: Stage D: Dynamical Interactionssupporting

confidence: 74%

How do binary separations depend on cloud initial conditions?

Sterzik

Durisen

Zinnecker

2003

A&A

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“…It is possible for dynamical interactions in a small‐ N system to expel N − 2 objects and to leave only a tight binary (e.g. Kiseleva et al 1998). A star cluster born with a rich population of O stars could in principle be left with only two.…”

Section: Discussionmentioning

confidence: 99%

Wolf--Rayet and O star runaway populations from supernovae

Dray

Dale

Beer

et al. 2005

Monthly Notices of the Royal Astronomical Society

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We present numerical simulations of the runaway fractions expected amongst O and Wolf–Rayet star populations resulting from stars ejected from binaries by the supernova of the companion. Observationally, the runaway fraction for both types of star is similar, prompting the explanation that close dynamical interactions are the main cause of these high‐velocity stars. We show that, provided that the initial binary fraction is high, a scenario in which two‐thirds of massive runaways are from supernovae is consistent with these observations. Our models also predict a low frequency of runaways with neutron star companions and a very low fraction of observable Wolf–Rayet–compact companion systems.

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“…ii) Dynamical simulations (e.g. Kiseleva et al 1998) and observations (e.g. Goodman 2004) show that young stars may be displaced, by several pc per Myr, from the location where they were born, and thus removed from the reservoir of gas from which they formed iii) The large scale averages include non-star-forming parts of the ISM and the relative proportion of this 'inactive' gas will change when zooming in on smaller scales.…”

Section: Introductionmentioning

confidence: 99%

Star formation rates from young-star counts and the structure of the ISM across the NGC 346/N66 complex in the SMC★

Hony¹,

Gouliermis²,

Galliano³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The rate at which interstellar gas is converted into stars, and its dependence on environment, is one of the pillars on which our understanding of the visible Universe is build. We present a comparison of the surface density of young stars (Σ ) and dust surface density (Σ dust ) across NGC 346 (N66) in 115 independent pixels of 6×6 pc 2 . We find a correlation between Σ and Σ dust with a considerable scatter. A power law fit to the data yields a steep relation with an exponent of 2.6±0.2. We convert Σ dust to gas surface density (Σ gas ) and Σ to star formation rate (SFR) surface densities (Σ SFR ), using simple assumptions for the gas-to-dust mass ratio and the duration of star formation. The derived total SFR (4±1·10 −3 M yr −1 ) is consistent with SFR estimated from the H α emission integrated over the H α nebula. On small scales the Σ SFR derived using H α systematically underestimates the count-based Σ SFR , by up to a factor of 10. This is due to ionizing photons escaping the area, where the stars are counted. We find that individual 36 pc 2 pixels fall systematically above integrated disc-galaxies in the Schmidt-Kennicutt diagram by on average a factor of ∼7. The NGC 346 average SFR over a larger area (90 pc radius) lies closer to the relation but remains high by a factor of ∼3. The fraction of the total mass (gas plus young stars) locked in young stars is systematically high (∼10 per cent) within the central 15 pc and systematically lower outside (2 per cent), which we interpret as variations in star formation efficiency. The inner 15 pc is dominated by young stars belonging to a centrally condensed cluster, while the outer parts are dominated by a dispersed population. Therefore, the observed trend could reflect a change of star formation efficiency between clustered and non-clustered star-formation.

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High-velocity stars from decay of small stellar systems

Cited by 9 publications

References 23 publications

How do binary separations depend on cloud initial conditions?

How do binary separations depend on cloud initial conditions?

Wolf--Rayet and O star runaway populations from supernovae

Star formation rates from young-star counts and the structure of the ISM across the NGC 346/N66 complex in the SMC★

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