Issue |
A&A
Volume 578, June 2015
|
|
---|---|---|
Article Number | A35 | |
Number of page(s) | 11 | |
Section | Galactic structure, stellar clusters and populations | |
DOI | https://doi.org/10.1051/0004-6361/201425514 | |
Published online | 29 May 2015 |
The Gaia-ESO Survey: N-body modelling of the Gamma Velorum cluster
1
INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122
Padova, Italy
e-mail: michela.mapelli@oapd.inaf.it
2
Astrophysics Group, Keele University, Keele, Staffordshire
ST5 5BG,
UK
3
Institute for Computational Science, University of
Zurich, Winterthurerstrasse
190, 8057
Zurich,
Switzerland
4
INAF–Osservatorio Astrofisico di Arcetri,
Largo E. Fermi 5, 50125
Florence,
Italy
5
Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27,
8093
Zurich,
Switzerland
6
Instituto de Astrofísica de Andalucía-CSIC,
Apdo. 3004, 18080
Granada,
Spain
7
INAF–Osservatorio Astronomico di Palermo,
Piazza del Parlamento 1,
90134
Palermo,
Italy
8
INAF–Osservatorio Astrofisico di Catania,
via S. Sofia 78, 95123
Catania,
Italy
9
Dipartimento di Fisica e Astronomia, Sezione Astrofisica,
Università di Catania, via S. Sofia
78, 95123
Catania,
Italy
10
INAF–Osservatorio Astronomico di Bologna,
via Ranzani 1, 40127
Bologna,
Italy
11
ASI Science Data Center, via del Politecnico SNC, 00133
Roma,
Italy
12
Institute of Astronomy, University of Cambridge,
Madingley Road, Cambridge
CB3 0HA,
UK
13
Astrophysics Research Institute, Liverpool John Moores
University, 146 Brownlow
Hill, Liverpool
L3 5RF,
UK
Received:
14
December
2014
Accepted:
9
April
2015
The Gaia-ESO Survey has recently unveiled the complex kinematic signature of the Gamma Velorum cluster: this cluster is composed of two kinematically distinct populations (hereafter, population A and B), showing two different velocity dispersions and a relative ~ 2 km s-1 radial velocity (RV) shift. In this paper, we propose that the two populations of the Gamma Velorum cluster originate from two different sub-clusters, born from the same parent molecular cloud. We investigate this possibility by means of direct-summation N-body simulations. Our scenario is able to reproduce not only the RV shift and the different velocity dispersions, but also the different centroid (~0.5 pc), the different spatial concentration and the different line-of-sight distance (~5 pc) of the two populations. The observed 1−2 Myr age difference between the two populations is also naturally explained by our scenario, in which the two sub-clusters formed in two slightly different star formation episodes. Our simulations suggest that population B is strongly supervirial, while population A is close to virial equilibrium. We discuss the implications of our models for the formation of young star clusters and OB associations in the Milky Way.
Key words: methods: numerical / open clusters and associations: individual: Gamma Velorum cluster / stars: formation / stars: kinematics and dynamics
© ESO, 2015
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