The dynamics of the γ Vel cluster and nearby Vela OB2 association

Abstract

The kinematics of low-mass stars in nearby OB associations can provide clues about their origins and evolution. Combining the precise positions, proper motions and parallaxes given in the second Gaia Data Release with radial velocity measurements obtained with the Hermes spectrograph at the Anglo-Australian Telescope, we have an opportunity to study in detail the kinematics of low-mass stars belonging to the nearby $\gamma$ Vel cluster and the Vela OB2 association it is projected against. The presence of lithium is used to confirm the youth of our targets. We separate our sample into the cluster and association populations based on the membership probabilities of Jeffries et al. 2014, their parallaxes, and kinematics. We find strong evidence for expansion in the OB association population with at least 4$\sigma$ significance along all three axes, though the expansion is notably anisotropic. We discuss these results in the context of cluster and association dispersal theories.

9 pages, 8 figures, 1 table, accepted for publication in MNRAS

References in corpus (10)

• The Gaia mission
• A comprehensive set of simulations studying the influence of gas expulsion on star cluster evolution
• Gaia Data Release 1: Catalogue validation
• The stellar association around Gamma Velorum and its relationship with Vela OB2
• γ^2 Velorum: Orbital Solution and Fundamental Parameter Determination with SUSI
• The Gaia-ESO Survey: Lithium depletion in the Gamma Velorum cluster and inflated radii in low-mass pre-main-sequence stars
• Not all stars form in clusters - measuring the kinematics of OB associations with $Gaia$
• The Gaia-ESO Survey: Asymmetric expansion of the Lagoon Nebula cluster NGC 6530 from GES and Gaia DR2
• The Gaia-ESO Survey: Discovery of a spatially extended low-mass population in the Vela OB2 association
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Cited by in corpus (11)

• OB associations and their origins
• Kalkayotl: A cluster distance inference code
• Disruption of Hierarchical Clustering in the Vela OB2 Complex and the Cluster Pair Collinder 135 and UBC7 with Gaia EDR3: Evidence of Supernova Quenching
• Large-scale expansion of OB stars in Cygnus
• Early dynamical evolution of rotating star clusters in a tidal field
• The Gaia-ESO Survey: Constraining evolutionary models and ages for young low mass stars with measurements of lithium depletion and rotation
• Mapping the distribution of OB stars and associations in Auriga
• The Structure and 3D Kinematics of Vela OB2
• The Stellar "Snake" I: Whole Structure and Properties
• Expansion Kinematics of Young Clusters. I. Lambda Ori
• Peculiarities of Open Star Clusters with High Vertical Velocities from the Region of the Sco-Cen OB Association