Article (Scientific journals)
A Gaia view of the two OB associations Cygnus OB2 and Carina OB1: the signature of their formation process
Lim, Beomdu; Nazé, Yaël; Gosset, Eric et al.
2019In Monthly Notices of the Royal Astronomical Society, 490, p. 440-454
Peer reviewed
 

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Keywords :
stars: formation; stars: kinematics and dynamics; open clusters and associations: individual (Cygnus OB2 and Carina OB1)
Abstract :
[en] OB associations are the prime star-forming sites in galaxies. However, the detailed formation process of such stellar systems still remains a mystery. In this context, identifying the presence of substructures may help in tracing the footprints of their formation process. Here, we present a kinematic study of the two massive OB associations Cygnus OB2 and Carina OB1 using the precise astrometry from the Gaia Data Release 2 and radial velocities. From the parallaxes of stars, these OB associations are confirmed to be genuine stellar systems. Both Cygnus OB2 and Carina OB1 are composed of a few dense clusters and a halo which have different kinematic properties: the clusters occupy regions of 5-8 parsecs in diameter and display small dispersions in proper motion, while the haloes spread over tens of parsecs with two to three times larger dispersions in proper motion. This is reminiscent of the so-called line width-size relation of molecular clouds related to turbulence. Considering that the kinematics and structural features were inherited from those of their natal clouds would then imply that the formation of OB associations may result from structure formation driven by supersonic turbulence, rather than from the dynamical evolution of individual embedded clusters.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Lim, Beomdu  ;  School of Space Research, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea ; Space Sciences, Technologies and Astrophysics Research Institute, Université de Liège, Quartier Agora, Allée du 6 Août 19c, Bât. B5c, B-4000 Liège, Belgium ; Department of Astronomy and Space Science, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea
Nazé, Yaël  ;  Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Gosset, Eric ;  Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Rauw, Grégor  ;  Université de Liège - ULiège > Groupe d'astrophysique des hautes énergies (GAPHE)
Language :
English
Title :
A Gaia view of the two OB associations Cygnus OB2 and Carina OB1: the signature of their formation process
Publication date :
01 November 2019
Journal title :
Monthly Notices of the Royal Astronomical Society
Volume :
490
Pages :
440-454
Peer reviewed :
Peer reviewed
Available on ORBi :
since 16 October 2019

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