The luminosities and periods of obscured AGB stars in the LMC are discussed using a combination of ISO and ground-based infrared photometry. The bolometric luminosities of these stars fall close to an extrapolation of the period-luminosity relation derived for oxygen-rich Mira variables, with both oxygenand carbon-rich stars falling close to the same relation. It has been known for many years t...

We present K -band commissioning observations of the Mira star prototype o Cet obtained at the ESO Very Large Telescope Interferometer (VLTI) with the VLT INterferometer Commissioning Instrument (VINCI) and two siderostats. The observations were carried out between 2001 October and December, in 2002 January and December, and in 2003 January. Rosseland angular radii are derived from the measured...

We present period–luminosity relations for more than 23 000 red giants in the Large Magellanic Cloud observed by the OGLE-II microlensing project. The OGLE period values were combined with the 2MASS single-epoch JHKS photometric data. For the brighter stars we find agreement with previous results (four different sequences corresponding to different modes of pulsation in asymptotic giant branch ...

A tomographic method is described that makes it possible to follow the propagation of shock waves across the photosphere of long-period variable stars. The method relies on the correlation of the observed spectrum with numerical masks probing layers of different atmospheric depths. The formation depth of spectral lines is derived from synthetic spectra of non-variable red giant stars. When appl...

The OH 1667 MHz maser in the circumstellar shell around the Mira variable U Her has been observed with the NRAO Very Long Baseline Array (VLBA) at 6 epochs, spread over 4 years. Using phase referencing techniques the position of the most blue-shifted maser spot was monitored with respect to two extra-galactic radio sources. The absolute radio positions of the maser can be compared with the stel...

We present the first spatially resolved observations of a sample of 23 Mira stars simultaneously measured in the near-infrared J, H and K ′ bands. The technique used was optical long baseline interferometry, and we present for each star visibility amplitude measurements as a function of wavelength. We also present characteristic sizes at each spectral band, obtained by fitting the measured visi...

The most direct evidence for the pulsation mode of Mira and SR variables comes from the linear diameters derived from individual parallaxes and angular diameters, together with the observed periods. The data now available strongly suggest that most, if not all, Miras and SRs pulsate in the same mode. If comparison is made with conventional models, this mode is the first overtone. Uncertainties ...

We present K ′-band observations of five Mira stars with the IOTA interferometer. The interferograms were obtained with the FLUOR fiber optics beam combiner, which provides high-accuracy visibility measurements in spite of time-variable atmospheric conditions. For the M-type Miras X Oph, R Aql, RU Her, R Ser, and the C-type Mira V CrB we derived the uniform-disk diameters 11.7 mas, 10.9 mas, 8....

We present optical interferometric polarimetry measurements of the Mira-like variables R Car and RR Sco, using the Sydney University Stellar Interferometer. By making visibility measurements in two perpendicular polarisations, the relatively low-surface brightness light scattered by atmospheric dust could be spatially separated from the bright Mira photospheric flux. This is the first reported ...