Search for associations containing young stars (SACY). VII. New stellar and substellar candidate members in the young associations



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Elliott, P. and Bayo, A. and Melo, C. H. F. and Torres, C. A. O. and Sterzik, M. F. and Quast, G. R. and Montes Gutiérrez, David and Brahm, R. (2016) Search for associations containing young stars (SACY). VII. New stellar and substellar candidate members in the young associations. Astronomy & Astrophysics, 590 . ISSN 1432-0746

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Context. The young associations offer us one of the best opportunities to study the properties of young stellar and substellar objects and to directly image planets thanks to their proximity (<200 pc) and age (≈5−150 Myr). However, many previous works have been limited to identifying the brighter, more active members (≈1 M_⊙) owing to photometric survey sensitivities limiting the detections of lower mass objects. Aims. We search the field of view of 542 previously identified members of the young associations to identify wide or extremely wide (1000−100 000 au in physical separation) companions. Methods. We combined 2MASS near-infrared photometry (J, H, K) with proper motion values (from UCAC4, PPMXL, NOMAD) to identify companions in the field of view of known members. We collated further photometry and spectroscopy from the literature and conducted our own high-resolution spectroscopic observations for a subsample of candidate members. This complementary information allowed us to assess the efficiency of our method. Results. We identified 84 targets (45: 0.2−1.3 M_⊙, 17: 0.08−0.2 M_⊙, 22: <0.08 M_⊙) in our analysis, ten of which have been identified from spectroscopic analysis in previous young association works. For 33 of these 84, we were able to further assess their membership using a variety of properties (X-ray emission, UV excess, Hα, lithium and K I equivalent widths, radial velocities, and CaH indices). We derive a success rate of 76–88% for this technique based on the consistency of these properties. Conclusions. Once confirmed, the targets identified in this work would significantly improve our knowledge of the lower mass end of the young associations. Additionally, these targets would make an ideal new sample for the identification and study of planets around nearby young stars. Given the predicted substellar mass of the majority of these new candidate members and their proximity, high-contrast imaging techniques would facilitate the search for new low-mass planets.

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© ESO, 2016.
P.E. would like to thank A. Tokovinin for a visit in August 2015 that significantly helped to improve the data management of this project, in part making the analysis presented here possible. P.E. is also grateful to I. Baraffe for a finer grid of models upon request. A. Bayo acknowledges financial support from the Proyecto Fondecyt de Iniciación 11140572. D. Montes acknowledges financial support from the Spanish Ministerio de Economía y Competitividad under grants AYA2011-30147-C03-03 and AYA2014-54348-C3-3-R. This research has made use of the Washington Double Star catalogue maintained at the US Naval Observatory, the Topcat tool (Taylor 2005), the SIMBAD database, and the VizieR catalogue access tool, CDS, Strasbourg, France (the original description of the VizieR service was published in A&AS, 143, 23) We have used Catalina (CSS) data in our analysis. The CSS survey is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the US National Science Foundation under grants AST-0909182 and AST-1313422. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported from the Spanish MICINN through grant AyA2011-24052.

Uncontrolled Keywords:Low-mass stars; Pre-main-sequence; Lithium depletion boundary; Pictoris moving group; T-tauri stars; Kinematic groups; M-dwarfs; Solar neighborhood; Beta-pictoris; Proper-motion
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:38732
Deposited On:10 Aug 2016 14:46
Last Modified:10 Dec 2018 15:04

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