SIMBAD references

2017MNRAS.472.3887M - Mon. Not. R. Astron. Soc., 472, 3887-3904 (2017/December-3)

Kinematics of OB-associations in Gaia epoch.


Abstract (from CDS):

We use stellar proper motions from the Tycho-Gaia Astrometric Solution (TGAS) catalogue to study the kinematics of OB-associations. The TGAS proper motions of OB-associations generally agree well with the Hipparcos proper motions. The parameters of the Galactic rotation curve obtained with TGAS and Hipparcos proper motions agree within the errors. The average one-dimensional velocity dispersion inside 18 OB-associations with more than 10 TGAS stars is σv = 3.9 km s–1, which is considerably smaller, by a factor of 0.4, than the velocity dispersions derived from Hipparcos data. The effective contribution from orbital motions of binary OB-stars into the velocity dispersion σv inside OB-associations is σb = 1.2 km s–1. The median virial and stellar masses of OB-associations are equal to 7.1 x 105 and 9.0 x 103 M, respectively. Thus, OB-associations must be unbound objects, provided they do not include a lot of dense gas. The median star-formation efficiency is ε = 2.1 per cent. Nearly one-third of stars of OB-associations must lie outside their tidal radius. We found that the Per OB1 and Car OB1 associations are expanding with the expansion started in a small region of 11-27 pc 7-10 Myr ago. The average expansion velocity is 6.3 km s–1.

Abstract Copyright: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): Galaxy: kinematics and dynamics - open clusters and associations: general - open clusters and associations: individual: (Per OB1, Car OB1) - stars: formation - stars: formation

VizieR on-line data: <Available at CDS (J/MNRAS/472/3887): table1.dat table2.dat>

Simbad objects: 2146

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