The behavior of the spotless active regions during the solar minimum 23-24

Abstract

Abstract. In this work, we analysed the physical parameters of the spotless actives regions observed during solar minimum 23 -24 (2007 -2010). The study was based on radio maps at 17 GHz obtained by the Nobeyama Radioheliograph (NoRH) and magnetograms provided by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). The results shows that the spotless active regions presents the same radio characteristics of a ordinary one, they can live in the solar surface for long periods (> 10 days), and also can present small flares.