High-frequency SiO masers in long-period variable stars

Envelope tomography of long - period variable stars ⋆

This paper is the first one in a series devoted to the study of the dynamics of the atmospheres of longperiod variable (LPV) stars. Results from a two-monthlong monitoring of the Mira variables RTCyg and XOph around maximum light with the ELODIE spectrograph at the Haute-Provence Observatory are presented. The monitoring covers phases 0.80 to 1.16 for RTCyg and phases 0.83 to 1.04 for XOph. The...

Envelope tomography of long-period variable stars⋆ III. Line-doubling frequency among Mira stars

This paper presents statistics of the line-doubling phenomenon in a sample of 81 long-period variable (LPV) stars of various periods, spectral types and brightness ranges. The set of observations consists of 315 highresolution optical spectra collected with the spectrograph ELODIE at the Haute-Provence Observatory, during 27 observing nights at one-month intervals and spanning two years. When c...

The Absolute Magnitudes of Long Period Variable Stars.

Envelope tomography of long-period variable stars⋆ II. Method

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...

Tomography of the atmosphere of long-period variable stars

This paper reviews the results obtained so far with the newly developed tomographic technique, which probes the velocity field across the atmosphere of long-period variable (LPV) stars. The method cross-correlates the optical spectrum with numerical masks constructed from synthetic spectra and probing layers of increasing depths. This technique reveals that the line doubling often observed in L...