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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., 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., Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Plan Nacional de Astronomía y Astrofísica (PNAyA), MICINN, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2010. Part of this work was co-supported by the Spanish MICINN, Ministerio de Ciencia e Innovación project numbers: AYA2008- 00695 and AYA2008-06423-C03-03. J. López Santiago is a postdoctoral fellow of the ASTROCAM (Red de Astrofísica en la CAM) with project number S-0505/ESP/000237 of the IV PRICIT Plan Regional de Investigación Científica e Innovación Tecnológica de la Comunidad de Madrid. The authors would like to thank the referee for useful comments and suggestions that allowed us to improve our work., Aims. We present a compilation of spectroscopic data from a survey of 144 chromospherically active young stars in the solar neighborhood, which may be used to investigate different aspects of its formation and evolution in terms of kinematics and stellar formation history. The data have already been used by us in several studies. With this paper, we make all these data accessible to the scientific community for future studies on different topics. Methods. We performed spectroscopic observations with echelle spectrographs to cover the entirety of the optical spectral range simultaneously. Standard data reduction was performed with the IRAF echelle package. We applied the spectral subtraction technique to reveal chromospheric emission in the stars of the sample. The equivalent width of chromospheric emission lines was measured in the subtracted spectra and then converted to fluxes using equivalent width-flux relationships. Radial and rotational velocities were determined by the cross-correlation technique. Kinematics, equivalent widths of the lithium line lambda 6707.8 angstrom and spectral types were also determined. Results. A catalog of spectroscopic data is compiled: radial and rotational velocities, space motion, equivalent widths of optical chromospheric activity indicators from Ca II H & K to the calcium infrared triplet and the lithium line in lambda 6708 angstrom. Fluxes in the chromospheric emission lines and R(HK)' are also determined for each observation of a star in the sample. We used these data to investigate the emission levels of our stars. The study of the Ha emission line revealed two different populations of chromospheric emitters in the sample, clearly separated in the log F(H alpha)/F(bol) - (V - J) diagram. The dichotomy may be associated with the age of the stars., Spanish MICINN, Ministerio de Ciencia e Innovación, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© ESO, 2010. Based on observations made with the 2.2 m telescope at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto (Spain) and the Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Istituto Nazionale de Astrofisica Italiano (INAF), in the Spanish Observatorio del Roque de los Muchachos. This research has been supported by the Programa de Acceso a Infraestructuras Científicas y Tecnológicas Singulares (ICTS). R. Martínez-Arnáiz acknowledges support from the Spanish Ministerio de Educación y Ciencia (currently the Ministerio de Ciencia e Innovación), under the grant FPI20061465-00592 (Programa Nacional Formación Personal Investigador) and projects AYA2008-00695 (Programa Nacional de Astronomía y Astrofísica), AYA2008-01727 (Programa Nacional de Astronomía y Astrofísica), AstroMadrid S2009/ESP-1496. This research has made use of the SIMBAD database and VizieR catalogue access tool, operated at CDS, Strasbourg, France. We also thank the anonymous referee for his/her valuable suggestions on how to improve the manuscript., Context. Chromospheric activity produces both photometric and spectroscopic variations that can be mistaken as planets. Large spots crossing the stellar disc can produce planet-like periodic variations in the light curve of a star. These spots clearly affect the spectral line profiles, and their perturbations alter the line centroids creating a radial velocity jitter that might “contaminate” the variations induced by a planet. Precise chromospheric activity measurements are needed to estimate the activity-induced noise that should be expected for a given star. Aims. We obtain precise chromospheric activity measurements and projected rotational velocities for nearby (d ≤ 25 pc) cool (spectral types F to K) stars, to estimate their expected activity-related jitter. As a complementary objective, we attempt to obtain relationships between fluxes in different activity indicator lines, that permit a transformation of traditional activity indicators, i.e., Ca II H & K lines, to others that hold noteworthy advantages. Methods. We used high resolution (~50 000) echelle optical spectra. Standard data reduction was performed using the IRAF ECHELLE package. To determine the chromospheric emission of the stars in the sample, we used the spectral subtraction technique. We measured the equivalent widths of the chromospheric emission lines in the subtracted spectrum and transformed them into fluxes by applying empirical equivalent width and flux relationships. Rotational velocities were determined using the cross-correlation technique. To infer activity-related radial velocity (RV) jitter, we used empirical relationships between this jitter and the R’_HK index. Results. We measured chromospheric activity, as given by different indicators throughout the optical spectra, and projected rotational velocities for 371 nearby cool stars. We have built empirical relationships among the most important chromospheric emission lines. Finally, we used the measured chromospheric activity to esti, Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Plan Nacional de I+D+i (MINECO), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub