Accretion in brown dwarfs:. a low-resolution criterion

Abstract. We present evidences of ongoing accretion and outflows in several objects at or below the substellar limit, including the width of the Hα line, the detection of forbidden lines and near-infrared excess. These objects are likely to belong to several SFRs, and have ages in the range 1-8 Myr. In addition, we present an accretion criterion based on low-resolution optical spectroscopy, which can be applied, from the statistical point of view, to large samples. Key words. Brown dwarfs – Accretion – open clusters 1. Brown Dwarfs, accretion, and high-and medium-resolution spectroscopy During the last few years, a growing amount of evidences has appeared in the literature con-cerning the brown dwarfs and accretion: they, indeed, seem to undergo a TTauri phase (Class II objects), which implies the presence of a circun(sub)stelar disk and a flux from it onto the central object, including the associated fea-tures such as UV and IR excesses, spectral veiling, a plethora of emission lines and so on. Moreover, outflows seem to be present too. Here, we present the spectra of several very low mass stars and young brown dwarfs, taken at medium- and high-resolution, which do show broad Hα and other permitted lines profiles and, in some cases, intense forbidden lines. Send offprint requests to: D. Barrado y Navascués