We report on the first ever detection of circular polarization in molecular lines forming in magnetic regions on the surfaces of active stars. The new observations were obtained with the high-resolution spectro-polarimeter ESPaDOnS recently installed at the Canada-France-Hawaii Telescope. In July 2005 we carried out a survey of 17 G-K-M stars including active main-sequence dwarfs and RS CVn-type giants and subgiants. All stars were found to possess surface magnetic fields producing average atomic Stokes-V signals of 0.05% to 0.5%. Three stars clearly showed circular polarization in molecular lines of 0.5% to 1%. The molecular Stokes-V signal is reminiscent of that observed in sunspots.
展开▼
