1. The Gaia-ESO Survey: Structural and dynamical properties of the young cluster Chamaeleon i
- Author
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Sacco, G. G., Spina, L., Randich, S., Palla, F., Parker, J., Jeffries, D., Jackson, R., Meyer, R., Mapelli, M., Lanzafame, C., Bonito, R., Damiani, F., Franciosini, E., Frasca, A., Klutsch, A., Prisinzano, L., Tognelli, E., Degl’Innocenti, S., Prada Moroni, P. G., Alfaro, J., Micela, G., Prusti, T., Barrado, D., Biazzo, K., Bouy, H., Bravi, L., Lopez-Santiago, J., Wright, J., Bayo, A., Gilmore, G., Bragaglia, A., Flaccomio, E., Koposov, S. E., Pancino, E., Casey, A. R., Costado, M. T., Donati, P., Hourihane, A., Jofré, P., Lardo, C., Lewis, J., Magrini, L., Monaco, L., Morbidelli, L., Sousa, S. G., Worley, C. C., Zaggia, S., Parker, R. J., Jeffries, R. D., Meyer, M. R., Lanzafame, A. C., Degl'Innocenti, S., Alfaro, E. J., Wright, N. J., Gilmore, Gerard [0000-0003-4632-0213], Koposov, Sergey [0000-0003-2644-135X], Worley, Clare [0000-0001-9310-2898], Apollo - University of Cambridge Repository, Sacco G.G., Spina L., Randich S., Palla F., Parker R.J., Jeffries R.D., Jackson R., Meyer M.R., Mapelli M., Lanzafame A.C., Bonito R., Damiani F., Franciosini E., Frasca A., Klutsch A., Prisinzano L., Tognelli E., Degl'Innocenti S., Prada Moroni P.G., Alfaro E.J., Micela G., Prusti T., Barrado D., Biazzo K., Bouy H., Bravi L., Lopez-Santiago J., Wright N.J., Bayo A., Gilmore G., Bragaglia A., Flaccomio E., Koposov S.E., Pancino E., Casey A.R., Costado M.T., Donati P., Hourihane A., Jofre P., Lardo C., Lewis J., Magrini L., Monaco L., Morbidelli L., Sousa S.G., Worley C.C., Zaggia S., Ministero dell'Istruzione, dell'Università e della Ricerca, Istituto Nazionale di Astrofisica, European Research Council, Fundação para a Ciência e a Tecnologia (Portugal), Pôle Gérontologie, Centre Hospitalier Universitaire de Nice (CHU Nice), Muséum national d'Histoire naturelle (MNHN), Watershed Associates Ltd, Istituto di Astrofisica Spaziale e Fisica cosmica - Palermo (IASF-Pa), Istituto Nazionale di Astrofisica (INAF), University of Turin, INAF - Osservatorio Astrofisico di Catania (OACT), Economía Política y Hacienda Pública, Estadística Económica y Empresarial y Política Económica, Universidad de Castilla-La Mancha (UCLM), INAF - Osservatorio Astronomico di Palermo (OAPa), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), INAF - Osservatorio Astrofisico di Arcetri (OAA), M2A 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Focas Research Institute, Dublin Institute of Technology, Institut national de recherche et de sécurité (Vandoeuvre lès Nancy) (INRS ( Vandoeuvre lès Nancy)), Hitotsubashi University, Department of Physiology and Pharmacology, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome]-Réseau International des Instituts Pasteur (RIIP)-Institut Pasteur, Fondation Cenci Bolognetti - Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Réseau International des Instituts Pasteur (RIIP), Universidade de Sao Paulo, Instituto Ocenografico, Department of Microbiology and Molecular Genetics, Michigan State University [East Lansing], Michigan State University System-Michigan State University System, Université libre de Bruxelles (ULB), and Newcastle University [Newcastle]
- Subjects
astro-ph.SR ,Stellar population ,open clustersand associations: individual: Chamaeleon I ,Individual: Chamaeleon I [Open clusters and associations] ,Open clusters and associations: Individual: Chamaeleon I ,Stars: Kinematics and dynamics ,Stars: Pre-main sequence ,Techniques: Spectroscopic ,astro-ph.GA ,stars: kinematics and dynamics ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,stars: pre-main sequence ,01 natural sciences ,Virial theorem ,Kinematics and dynamics [Stars] ,Stars: Kinematics and dynamic ,0103 physical sciences ,Cluster (physics) ,Mass segregation ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Stellar evolution ,QC ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,QB ,Physics ,Pre-main sequence [Stars] ,open clusters and associations: individual: Chamaeleon I ,010308 nuclear & particles physics ,Velocity dispersion ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,techniques: spectroscopic ,Star cluster ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Earth and Planetary Astrophysics ,Spectroscopic [Techniques] ,Equivalent width ,QB799 - Abstract
Investigating the physical mechanisms driving the dynamical evolution of young star clusters is fundamental to our understanding of the star formation process and the properties of the Galactic field stars. The young (~2 Myr) and partially embedded cluster Chamaeleon I is one of the closest laboratories for the study of the early stages of star cluster dynamics in a low-density environment. The aim of this work is to study the structural and kinematical properties of this cluster combining parameters from the high-resolution spectroscopic observations of the Gaia-ESO Survey with data from the literature. Our main result is the evidence of a large discrepancy between the velocity dispersion (σ = 1.14 ± 0.35 km s) of the stellar population and the dispersion of the pre-stellar cores (~0.3 km s) derived from submillimeter observations. The origin of this discrepancy, which has been observed in other young star clusters, is not clear. It has been suggested that it may be due to either the effect of the magnetic field on the protostars and the filaments or to the dynamical evolution of stars driven by two-body interactions. Furthermore, the analysis of the kinematic properties of the stellar population puts in evidence a significant velocity shift (~1 km s) between the two subclusters located around the north and south main clouds of the cluster. This result further supports a scenario where clusters form from the evolution of multiple substructures rather than from a monolithic collapse. Using three independent spectroscopic indicators (the gravity indicator γ, the equivalent width of the Li line at 6708 Å, and the Hα 10% width), we performed a new membership selection. We found six new cluster members all located in the outer region of the cluster, proving that Chamaeleon I is probably more extended than previously thought. Starting from the positions and masses of the cluster members, we derived the level of substructure Q, the surface density Σ, and the level of mass segregation Λ of the cluster. The comparison between these structural properties and the results of N-body simulations suggests that the cluster formed in a low-density environment, in virial equilibrium or a supervirial state, and highly substructured.© 2017 ESO., This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR) in the form of the grant >Premiale VLT 2012>. This work has been partially supported by PRIN-INAF-2014. The results presented here benefited from discussions held during the Gaia-ESO workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme. M.M. acknowledges financial support from the Italian Ministry of Education, University and Research (MIUR) through grant FIRB 2012 RBFR12PM1F, from INAF through grant PRIN-2014-14, and from the MERAC Foundation. S.G.S. acknowledges the support by Fundacao para a Ciencia e Tecnologia (FCT) through national funds and a research grant (project Ref. UID/FIS/04434/2013, and PTDC/FIS-AST/7073/2014). S.G.S. also acknowledge the support from FCT through Investigador FCT contract of reference IF/00028/2014 and POPH/FSE (EC) by FEDER funding through the program Programa Operacional de Factores de Competitividade COMPETE.
- Published
- 2017