The Long-period Variable W Cygni

On the period history of χ Cygni

We discuss the light variability of the Mira variable χ Cygni, present a homogeneous set of times of minimum and maximum light since its discovery date in 1686, and analyse the variations of the pulsation period. There is a substantial cycleto-cycle variation in the pulsations (standard error ∼ 6. d5) with quite strong evidence for a linearly increasing period. Quasicyclic patterns in the O−C d...

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...

The Absolute Magnitudes of Long Period Variable Stars.

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...

The systemic velocities of four long-period cataclysmic variable stars

Although a large number of orbital periods of cataclysmic variable stars (CVs) have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been discovered which is independent of these selection effects and is based upon the kinematics of CVs (Kolb & Stehle, 1996). If the standard models of evolution are corr...