The OH main line masers in circumstellar shells were observed with astrometric VLBI in order to accurately determine the position of the star, as well as its motion, including the parallax. Results are presented on 4 Mira stars monitored for 2-8 years with the VLBA. The data show that in some stars the VLBI detection is dominated by blue-shifted emission that is associated with the stellar imag...

Highly sensitive simultaneous observations of the 2→1 line of the first vibrationally excited state of SiO, and of the 2→1 line of CO have been obtained toward 37 O-rich evolved stars. In ∼ 45% of these objects, the SiO line profiles present unusually broad wings, reaching, and in some cases exceeding, the terminal velocity of the circumstellar envelope. All of the objects exhibiting SiO line w...

The distance to NGC 5128, the central galaxy of the Centaurus group and the nearest giant elliptical to us, has been determined using two independent distance indicators: the Mira period-luminosity (PL) relation and the luminosity of the tip of the red giant branch (RGB). The data were taken at two different locations in the halo of NGC 5128 with the ISAAC near-IR array on ESO VLT. From more th...

Observations of five D-type symbiotics are presented: three oxygen Mira (He2-38, H2-38 and H1-36) and two carbon Mira symbiotics (AS 210 and SS 38). The observations in the spectral range between 3200Å and 7400Å show the presence of several emission lines in various states of excitation. A line list is provided with their suggested identifications. Several parameters were derived for each objec...

Aims. Accurate distances to evolved stars with high mass loss rates are needed for studies of many of their fundamental properties. However, as these stars are heavily obscured and variable, optical and infrared astrometry is unable to provide enough accuracy. Methods. Astrometry using masers in the circumstellar envelopes can be used to overcome this problem. We have observed the OH masers of ...