Chromospheric activity, lithium and radial velocities of single late-type stars possible members of young moving groups



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Montes Gutiérrez, David and López Santiago, Javier and Fernández Figueroa, María José and Galves, M. C. (2001) Chromospheric activity, lithium and radial velocities of single late-type stars possible members of young moving groups. Astronomy and astrophysics, 379 (3). pp. 976-991. ISSN 0004-6361

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We present here high resolution echelle spectra taken during three observing runs of 14 single late-type stars identified in our previous studies (Montes et al. 2001b, hereafter Paper I) as possible members of different young stellar kinematic groups (Local Association (20-150 Myr), Ursa Major group (300 Myr), Hyades supercluster (600 Myr), and IC 2391 supercluster (35 Myr)). Radial velocities have been determined by cross correlation with radial velocity standard stars and used together with precise measurements of proper motions and parallaxes taken from Hipparcos and Tycho-2 Catalogues, to calculate Galactic space motions (U, V, W) and to apply Eggen's kinematic criteria. The chromospheric activity level of these stars have been analysed using the information provided for several optical spectroscopic features (from the CaII H & K toCaII IRT lines) that are formed at different heights in the chromosphere. The Li I λ6707.8 Å line equivalent width (EW) has been determined and compared in the EW(Li I) versus spectral type diagram with the EW(Li I) of stars members of well-known young open clusters of different ages, in order to obtain an age estimation. All these data allow us to analyse in more detail the membership of these stars in the different young stellar kinematic groups. Using both, kinematic and spectroscopic criteria we have confirmed PW And, V368 Cep, V383 Lac, EP Eri, DX Leo, HD 77407, and EK Dra as members of the Local Association and V834 Tau, π^1 UMa, and GJ 503.2 as members of the Ursa Major group. A clear rotation-activity dependence has been found in these stars.

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© ESO 2001. We would like to thank Dr. B. H. Foing for allowing us to use the ESA-MUSICOS spectrograph at Isaac Newton Telescope. This research has made use the of the SIMBAD data base, operated at CDS, Strasbourg, France, and the ARI Database for Nearby Stars, Astronomisches RechenInstitut, Heidelberg. We would also like to thank the referee S. Catalano for suggesting several improvements and clarifications. This work was supported by the Universidad Complutense de Madrid and the Spanish Dirección General de Enseñanza Superior e Investigación Científica (DGESIC) under grant PB97-0259.

Uncontrolled Keywords:Solar-type stars; Main-sequence stars; Ursa-major group; Multiwavelength optical observations; Stellar kinematic groups; Rotation-activity connection; Extreme-ultraviolet sources; Wide-field camera; All-sky survey; Low-mass stars
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:31490
Deposited On:04 Aug 2015 07:19
Last Modified:10 Dec 2018 15:05

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