An exceptional variability phase occurred in the peculiar F-type hypergiant ρ Cas (Ia+) when the V brightness dimmed by about a full magnitude between June and September 2000. The star recovered from this deep minimum by April 2001. It is the third outburst of ρ Cas on record in the last century. We detect the formation of TiO bands in high

We obtained at the same time G-band images at the Dutch Open Telescope (DOT) on La Palma and spectropolarimetric data in the near infrared at the German Vacuum Tower Telescope (VTT) on Tenerife. The spectropolarimetric data show interesting correlations. Bright filaments have a smaller magnetic field s trength, and higher Evershed velocities occur

We present a method to reduce noise in helioseismic power spectra using a non-orthogonal wavelet transform based on quadratic spline functions. The quality of our method is tested by applying it to artificially generated time-series approximating solar p-modes. The mode frequencies and line widths obtained from least-squares fits to the smoothed

We have obtained intermediate resolution optical spectra of the black-hole candidate Nova Sco 1994 in June 1996, when the source was in an X-ray/optical active state (R~15.05). We measure the radial velocity curve of the secondary star and obtain a semi-amplitude of 279+/-10 km s-1 a value which is 30 per cent larger than the value obtained when

Bright circumstellar nebulae around massive stars are potentially useful to derive time-dependent mass-loss rates and hence constrain the evolution of the central stars. A key case in this context is the relatively young ejection-type nebula M1-67 around the runaway Population I Wolf-Rayet star WR 124 (=209 BAC), which exhibits a WN 8 spectrum

We analysed high resolution spectra of Galactic O-type stars from the far-UV to the optical. We combined spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE) in the range 905-1187Å, IUE or HST archive spectra (1150-3300Å), and optical blue and Hα spectra from the La Palma INT. The spectra were analysed with line-blanketed, hydrodynamic