Volume 574, February 2015
|Number of page(s)||5|
|Published online||26 January 2015|
The Gaia-ESO survey: Discovery of a spatially extended low-mass population in the Vela OB2 association⋆,⋆⋆
INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5,
2 Astrophysics Group, Research Institute for the Environment, Physical Sciences and Applied Mathematics, Keele University, Keele, Staffordshire ST5 5BG, UK
3 Institute of Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
4 INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
5 Instituto de Astrofísica de Andalucía-CSIC, Apdo. 3004, 18080 Granada, Spain
6 Dipartimento di Fisica e Chimica, Universitá di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
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, Universitá di Catania, via S. Sofia 78, 95123 Catania, Italy
10 Instituto de Física y Astronomía, Universidad de Valparaíso, av. Gran Bretaña 1111, Valparaíso, Chile
11 Depto. de Astrofísica, Centro de Astrobiología (CSIC-INTA), ESAC campus, 28691 Villanueva de la Cañada, Madrid, Spain
12 Suffolk University, Madrid Campus, C/ Valle de la Viña 3, 28003 Madrid, Spain
13 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
14 Instituto de Astrofísica de Canarias, 38205, La Laguna, Tenerife, Spain
15 European Southern Observatory, Alonso de Cordova 3107 Vitacura, Santiago de Chile, Chile
16 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
17 Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile
Received: 19 November 2014
Accepted: 23 December 2014
The nearby (distance ~ 350–400 pc), rich Vela OB2 association, includes γ2 Velorum, one of the most massive binaries in the solar neighbourhood and an excellent laboratory for investigating the formation and early evolution of young clusters. Recent Gaia-ESO survey observations have led to the discovery of two kinematically distinct populations in the young (10–15 Myr) cluster immediately surrounding γ2 Velorum. Here we analyse the results of Gaia-ESO survey observations of NGC 2547, a 35 Myr cluster located two degrees south of γ2 Velorum. The radial velocity distribution of lithium-rich pre-main sequence stars shows a secondary population that is kinematically distinct from and younger than NGC 2547. The radial velocities, lithium absorption lines, and the positions in a colour-magnitude diagram of this secondary population are consistent with those of one of the components discovered around γ2 Velorum. This result shows that there is a young, low-mass stellar population spread over at least several square degrees in the Vela OB2 association. This population could have originally been part of a cluster around γ2 Velorum that expanded after gas expulsion or formed in a less dense environment that is spread over the whole Vela OB2 region.
Key words: stars: formation / stars: pre-main sequence / techniques: spectroscopic / stars: individual: gamma2 Velorum / open clusters and associations: individual: Vela OB2 / open clusters and associations: individual: NGC 2547
Based on observations made with the ESO/VLT, at Paranal Observatory, under program 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey).
Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/L7
© ESO, 2015
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