Examinando por Autor "Meyer, M.R."

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    The Gaia -ESO Survey: Chemical signatures of rocky accretion in a young solar-type star
    (EDP Sciences, 2015-10) Spina, L.; Palla, F.; Randich, S.; Sacco, G.; Jeffries, R.; Magrini, L.; Franciosini, E.; Meyer, M.R.; Tautvaišiene, G.; Gilmore, G.; Alfaro, E.J.; Allende Prieto, C.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Koposov, S.E.; Lvanzafame, A.C.; Costado, M.T.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Sousa, S.G.; Worley, C.C.; Zaggia, S.
    It is well known that newly formed planetary systems undergo processes of orbital reconfiguration and planetary migration. As a result, planets or protoplanetary objects may accrete onto the central star, being fused and mixed into its external layers. If the accreted mass is sufficiently high and the star has a sufficiently thin convective envelope, such events may result in a modification of the chemical composition of the stellar photosphere in an observable way, enhancing it with elements that were abundant in the accreted mass. The recent Gaia-ESO Survey observations of the 10-20 Myr old Gamma Velorum cluster have enabled identifying a star that is significantly enriched in iron with respect to other cluster members. In this Letter we further investigate the abundance pattern of this star, showing that its abundance anomaly is not limited to iron, but is also present in the refractory elements, whose overabundances are correlated with the condensation temperature. This finding strongly supports the hypothesis of a recent accretion of rocky material. © ESO, 2015.
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    The Gaia-ESO survey: Dynamical analysis of the L1688 region in Ophiuchus
    (EDP Sciences, 2016-04) Rigliaco, E.; Wilking, B.; Meyer, M.R.; Jeffries, R.D.; Cottaar, M.; Frasca, A.; Wright, N.J.; Bayo, A.; Bonito, R.; Damiani, F.; Jackson, R.J.; Jiménez-Esteban, F.; Kalari, V.M.; Klutsch, A.; Lanzafame, A.C.; Sacco, G.; Gilmore, G.; Randich, S.; Alfaro, E.J.; Bragaglia, A.; Costado, M.T.; Franciosini, E.; Lardo, C.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sousa, S.G.; Zaggia, S.
    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.