%0 Journal Article
%T Stars and brown dwarfs in the 考 Orionis cluster - IV. IDS/INT and OSIRIS/GTC spectroscopy and Gaia DR2 astrometry
%A A. Cabrera-Lavers
%A A. de Burgos
%A D. Garc赤a-芍lvarez
%A D. Montes
%A F. J. Alonso-Floriano
%A J. A. Caballero
%J -
%D 2019
%R 10.1051/0004-6361/201935987
%X <i>Context.<i/> Only a few open clusters are as important for the study of stellar and substellar objects, and their formation and evolution, as the young <i>考<i/> Orionis cluster. However, a complete spectroscopic characterisation of its whole stellar population is still missing.<i>Aims.<i/> We filled most of that gap with a large spectroscopic and astrometric survey of targets towards <i>考<i/> Orionis. Eventually, it will be one of the open clusters with the lowest proportion of interlopers and the largest proportion of confirmed cluster members with known uncontrovertible youth features.<i>Methods.<i/> We acquired 317 low-resolution optical spectra with the Intermediate Dispersion Spectrograph (IDS) at the 2.5 m <i>Isaac Newton<i/> Telescope (INT) and the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) at the 10.4 m Gran Telescopio Canarias (GTC). We measured equivalent widths of LiˋI, H<i>汐<i/>, and other key lines from these spectra, and determined spectral types. We complemented this information with <i>Gaia<i/> DR2 astrometric data and other features of youth (mid-infrared excess, X-ray emission) compiled with Virtual Observatory tools and from the literature.<i>Results.<i/> Of the 168 observed targets, we determined for the first time spectral types of 39 stars and equivalent widths of LiˋI and H<i>汐<i/> of 34 and 12 stars, respectively. We identified 11 close (<i>老<i/>ˋˋˋ3 arcsec) binaries resolved by <i>Gaia<i/>, of which three are new, 14 strong accretors, of which four are new and another four have H<i>汐<i/> emission shifted by over 120 km s<sup>ˋ1<sup/>, two juvenile star candidates in the sparse population of the Ori OB1b association, and one spectroscopic binary candidate. Remarkably, we found 51 non-cluster-members, 35 of which were previously considered as <i>考<i/> Orionis members and taken into account in high-impact works on, for example, disc frequency and initial mass function
%U https://www.aanda.org/articles/aa/full_html/2019/09/aa35987-19/aa35987-19.html