2012A&A...539A..86J

With available Virtual Observatory tools, we looked for new M dwarfs in the solar neighbourhood and M giants with high tangential velocities. From an all-sky cross-match between the optical Tycho-2 and the near-infrared 2MASS catalogues, we selected objects with proper motions µ>50mas/yr and very red V_T-K_s colours. For the most interesting targets, we collected multi-wavelength photometry, constructed spectral energy distributions, estimated effective temperatures and surface gravities from fits to atmospheric models, performed time-series analysis of ASAS V-band light curves, and assigned spectral types from low-resolution spectroscopy obtained with CAFOS at the 2.2m Calar Alto telescope. We got a sample of 59 bright red high proper-motion objects, including fifty red giants, four red dwarfs, and five objects reported in this work for the first time. The five new stars have magnitudes V_T≃10.8-11.3mag, reduced proper motions midway between known dwarfs and giants, near-infrared colours typical of giants, and effective temperatures T_eff≃2900-3400K. From our time-series analysis, we discovered a long secondary period in Ruber4 and an extremely long primary period in Ruber6. With the CAFOS spectra, we confirmed the red giant nature of Ruber7 and 8, the last of which seems to be one of the brightest metal-poor M giants ever identified.