The Gaia-ESO Survey: Dynamical analysis of the L1688 region in Ophiuchus

¹ Institute for Astronomy, Department of Physics, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8046 Zürich, Switzerland
e-mail: elisabetta.rigliaco@phys.ethz.ch
² Department of Physics and Astronomy, University of Missouri-St. Louis, 1 University Boulevard, St. Louis, MO 63121, USA
³ Astrophysics Group, Research Institute for the Environment, Physical Sciences and Applied Mathematics, Keele University, Keele, Staffordshire ST5 5BG, UK
⁴ INAF−Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
⁵ Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
⁶ Instituto de Física y Astronomiía, Universidad de Valparaíso, 1111 Gran Bretana, Playa Ancha, Chile
⁷ Dipartimento di Fisica e Chimica, Universitá di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁸ INAF−Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁹ Centro de Astrobiología (INTA-CSIC), Departamento de Astrofísica, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
¹⁰ Suffolk University, Madrid Campus, C/ Valle de la Viña 3, 28003 Madrid, Spain
¹¹ Armagh Observatory, College Hill, Armagh BT61 9DG, UK
¹² Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Universitá di Catania, via S. Sofia 78, 95123 Catania, Italy
¹³ INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, 50125 Firenze, Italy
¹⁴ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹⁵ Instituto de Astrofísica de Andalucía-CSIC, Apdo. 3004, 18080 Granada, Spain
¹⁶ INAF−Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
¹⁷ Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
¹⁸ Departamento de Ciencias Fisicas, Universidad Andres Bello, 220 Republica, Santiago, Chile
¹⁹ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
²⁰ INAF−Padova Observatory, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

Received: 26 August 2015
Accepted: 9 January 2016

Abstract

The Gaia ESO Public Spectroscopic Survey (GES) is providing the astronomical community with high-precision measurements of many stellar parameters including radial velocities (RVs) of stars belonging to several young clusters and star-forming regions. One of the main goals of the young cluster observations is to study their dynamical evolution and provide insight into their future, revealing whether they will eventually disperse to populate the field rather than evolve into bound open clusters. In this paper we report the analysis of the dynamical state of L1688 in the ρ Ophiuchi molecular cloud using the dataset provided by the GES consortium. We performed the membership selection of the more than 300 objects observed. Using the presence of the lithium absorption and the location in the Hertzspung-Russell diagram, we identify 45 already known members and two new association members. We provide accurate RVs for all 47 confirmed members. A dynamical analysis, after accounting for unresolved binaries and errors, shows that the stellar surface population of L1688 has a velocity dispersion σ ~ 1.14 ± 0.35 km s^-1 that is consistent with being in virial equilibrium and is bound with a ~80% probability. We also find a velocity gradient in the stellar surface population of ~1.0 km s^-1 pc^-1 in the northwest-southeast direction, which is consistent with that found for the pre-stellar dense cores, and we discuss the possibility of sequential and triggered star formation in L1688.