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A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups

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Maldonado, J. and Martínez Arnáiz, R. M. and Eiroa, C. and Montes Gutiérrez, David and Montesinos, B. (2010) A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups. Astronomy & Astrophysics, 521 . ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361/201014948


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Abstract

Context. Nearby late-type stars are excellent targets for seeking young objects in stellar associations and moving groups. The origin of these structures is still misunderstood, and lists of moving group members often change with time and also from author to author. Most members of these groups have been identified by means of kinematic criteria, leading to an important contamination of previous lists by old field stars.
Aims. We attempt to identify unambiguous moving group members among a sample of nearby-late type stars by studying their kinematics, lithium abundance, chromospheric activity, and other age-related properties.
Methods. High-resolution echelle spectra (R ~ 57 000) of a sample of nearby late-type stars are used to derive accurate radial velocities that are combined with the precise Hipparcos parallaxes and proper motions to compute galactic-spatial velocity components. Stars are classified as possible members of the classical moving groups according to their kinematics. The spectra are also used to study several age-related properties for young late-type stars, i.e., the equivalent width of the lithium Li i 6707.8 Å line or the R'_HK index. Additional information like X-ray fluxes from the ROSAT All-Sky Survey or the presence of debris discs is also taken into account. The different age estimators are compared and the moving group membership of the kinematically selected candidates are discussed.
Results. From a total list of 405 nearby stars, 102 have been classified as moving group candidates according to their kinematics. i.e., only ~25.2% of the sample. The number reduces when age estimates are considered, and only 26 moving group candidates (25.5% of the 102 candidates) have ages in agreement with the star having the same age as an MG member.


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© ESO, 2010.
We acknowledge J. López Santiago, I. Ribas, and J. Sanz Forcada for their valuable suggestions that contributed to improving this manuscript. J. M., C. E., and B. M. acknowledge support from the Spanish Ministerio de Ciencia e Innovación (MICINN), Plan Nacional de Astronomía y Astrófisica, under grant AYA2008-01727, and the Comunidad de Madrid project ASTRID S-0505/ESP/00361. R. MA., and D. M. acknowledges support from the Spanish Ministerio de Ciencia e Innovación (MICINN), Plan Nacional de Astronomía y Astrófisica, under grant AYA2008-00695, and the Comunidad de Madrid project AstroMadrid S2009/ESP-1496. We would like to thank the staff at Calar Alto and Telescopio Nazionale Galileo for their assistance and help during the observing runs. This research has made use of the VizieR catalogue access tool and the SIMBAD database, both operated at the CDS, Strasbourg, France. We also thank the anonymous referee for his/her valuable suggestions on how to improve the manuscript.

Uncontrolled Keywords:Solar-type stars; Main-sequence stars; CA-II H; Ursa-Major group; Velocity standard stars; Young moving groups; Chromospherically active binaries; High-resolution spectroscopy; Mean radial-velocities; Planet search program
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:37800
Deposited On:23 May 2016 15:18
Last Modified:10 Dec 2018 15:05

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