2016A&A...590A.107O


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.20CET01:49:12

2016A&A...590A.107O - Astronomy and Astrophysics, volume 590A, 107-107 (2016/6-1)

Dynamical ejections of massive stars from young star clusters under diverse initial conditions.

OH S. and KROUPA P.

Abstract (from CDS):

We study the effects that initial conditions of star clusters and their massive star population have on dynamical ejections of massive stars from star clusters up to an age of 3Myr. We use a large set of direct N-body calculations for moderately massive star clusters (Mecl≃103.5M). We vary the initial conditions of the calculations, such as the initial half-mass radius of the clusters, initial binary populations for massive stars and initial mass segregation. We find that the initial density is the most influential parameter for the ejection fraction of the massive systems. The clusters with an initial half-mass radius rh(0) of 0.1 (0.3)pc can eject up to 50% (30)% of their O-star systems on average, while initially larger (rh(0)=0.8pc) clusters, that is, lower density clusters, eject hardly any OB stars (at most ≃4.5%). When the binaries are composed of two stars of similar mass, the ejections are most effective. Most of the models show that the average ejection fraction decreases with decreasing stellar mass. For clusters that are efficient at ejecting O stars, the mass function of the ejected stars is top-heavy compared to the given initial mass function (IMF), while the mass function of stars that remain in the cluster becomes slightly steeper (top-light) than the IMF. The top-light mass functions of stars in 3Myr old clusters in our N-body models agree well with the mean mass function of young intermediate-mass clusters in M 31, as reported previously. This implies that the IMF of the observed young clusters is the canonical IMF. We show that the multiplicity fraction of the ejected massive stars can be as high as ≃60%, that massive high-order multiple systems can be dynamically ejected, and that high-order multiples become common especially in the cluster. We also discuss binary populations of the ejected massive systems. Clusters that are initially not mass-segregated begin ejecting massive stars after a time delay that is caused by mass segregation. When a large kinematic survey of massive field stars becomes available, for instance through Gaia, our results may be used to constrain the birth configuration of massive stars in star clusters. The results presented here, however, already show that the birth mass-ratio distribution for O-star primaries must be near uniform for mass ratios q>=0.1.

Abstract Copyright: © ESO, 2016

Journal keyword(s): methods: numerical - stars: kinematics and dynamics - stars: massive - open clusters and associations: general - galaxies: star clusters: general

Simbad objects: 12

goto Full paper

goto View the reference in ADS

Number of rows : 12

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10659 1
2 2MASS J00433008+4052581 s*r 00 43 30.0747978189 +40 52 58.094442389 23.406 21.145 19.212 18.135 16.851 M2I 8 0
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14457 1
4 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1920 1
5 NAME 30 Dor 016 * 05 37 08.8775810516 -69 07 20.377571697 12.623 13.584 13.546   13.816 O2IIIf* 36 0
6 HD 38282 WR* 05 38 53.3788120199 -69 02 00.896643506   10.98 11.11 11.26   WN5/6h+WN6/7h 146 1
7 UCAC4 105-014417 WR* 05 38 55.5218836143 -69 04 26.810760074   16.66 16.08   14.89 WN5h 47 0
8 Cl Westerlund 2 OpC 10 23 58.1 -57 45 49   11.59 10.5     ~ 266 0
9 NGC 3603 HII 11 15 24 -61 15.0           ~ 926 2
10 NGC 6357 HII 17 26.5 -34 12           ~ 245 0
11 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11155 0
12 M 16 OpC 18 18 48 -13 48.4   6.58 6.0     ~ 923 2

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2016A&A...590A.107O and select 'bookmark this link' or equivalent in the popup menu


2020.01.20-01:49:12

© Université de Strasbourg/CNRS

    • Contact