Volume 626, June 2019
|Number of page(s)||18|
|Section||Galactic structure, stellar clusters and populations|
|Published online||05 June 2019|
Expanding associations in the Vela-Puppis region
3D structure and kinematics of the young population⋆
Institut de Ciències del Cosmos, Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, 08028 Barcelona, Spain
2 Astrophysics Group, Keele University, Keele ST5 5BG, UK
3 INAF, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy
4 Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstrasse 25/8, 6020 Innsbruck, Austria
Accepted: 18 April 2019
Context. The Vela-Puppis region is known to host the Vela OB2 association as well as several young clusters featuring OB and pre-main-sequence stars. Several spatial and kinematic subgroups have been identified in recent years.
Aims. By grouping stars based on their positions and velocity, we can address the question of the dynamical history of the region and the mechanisms that drove stellar formation. The Gaia DR2 astrometry and photometry enables us to characterise the 3D spatial and 3D kinematic distribution of young stars and to estimate the ages of the identified components.
Methods. We used an unsupervised classification method to group stars based on their proper motions and parallax. We studied the expansion rates of the different identified groups based on 3D velocities and on corrected tangential velocities. We used theoretical isochrones to estimate ages.
Results. The young stars can be separated into seven main groups of different ages and kinematical distribution. All groups are found to be expanding, although the expansion is mostly not isotropic.
Conclusions. The size of the region, the age substructure, and the anisotropic expansion rates are compatible with a prolonged period of star formation in a turbulent molecular cloud. The current kinematics of the stars cannot be explained by internal processes alone (such as gas expulsion).
Key words: open clusters and associations: individual: Vela OB2 / open clusters and associations: individual: Trumpler 10 / open clusters and associations: individual: NGC 2547 / open clusters and associations: individual: NGC 2451B / stars: pre-main sequence
The list of members of the young populations established in this study is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/626/A17
© ESO 2019
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