The GOLF experiment is a resonant scattering spectrophotometer in flight on board the SOHO mission, originally designed to measure the intensity of the solar radiation at 4 selected positions within the sodium doublet (D1 at λ 5896 and D2 at λ 5890 AA). Each position was determined by a modulated magnetic field and a combination of rotating

Recent searches for brown dwarfs have succeeded in finding these elusive objects. Massive brown dwarfs (40-70 Jupiter masses) have been found in the Pleiades, orbiting around a nearby star and, very recently, in the field. A review is given of their observed photometric and spectroscopic properties in the optical and near-infrared. The diagnosis of

We present mid-resolution spectroscopic observations of 35 stars reported to be weak T Tauri stars (WTTS) discovered by ROSAT in the Taurus-Auriga star-forming region (Wichmann et al. 1996). We have measured the equivalent widths of Hα and Li 1 670.8 nm in our spectra. On the basis of our higher-resolution data, we reassess the evolutionary status

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