With the aim of deriving the binary frequency among Ba and S stars, 56 new spectroscopic orbits (46 and 10, respectively) have been derived for these chemicallypeculiar red giants monitored with the CORAVEL spectrometers. These orbits are presented in this paper (38 orbits) and in a companion paper (Udry et al. 1998, Paper II; 18 orbits). The results for 12 additional long-period binary stars (...

We present the first cross–identifications of sources in the near–infrared DENIS survey and in the micro–lensing EROS survey in a field of about 0.5 square degrees around the optical center (OC) of the Large Mag-ellanic Cloud. We analyze the photometric history of these stars in the EROS data base and obtain light–curves for about 800 variables. Most of the stars are long period variables (Mira...

We present a period-luminosity-amplitude analysis of 5899 red giant and binary stars in the Large Magellanic Cloud, using publicly available observations of the MACHO project. For each star, we determined new periods, which were double-checked in order to exclude aliases and false periods. The period-luminosity relations confirm the existence of a short-period, small-amplitude P–L sequence at p...

We apply the concept of superradiance that was introduced by Dicke in 1954 to the OH molecule 1612MHz spectral line, which is often used for the detection of masers in the circumstellar envelopes of evolved stars. Because the detection of 1612MHz OH masers in the outer shells of envelopes of these stars implies the existence of a population inversion and a high level of velocity coherence, and ...

Using a new grism at the Keck Interferometer, we obtained spectrally dispersed (R ∼ 230) interferometric measurements of the Mira star R Vir. These data show that the measured radius of the emission varies substantially from 2.0-2.4 μm. Simple models can reproduce these wavelength-dependent variations using extended molecular layers, which absorb stellar radiation and re-emit it at longer wavel...

We apply the concept of superradiance introduced by Dicke in 1954 to the OH molecule 1612 MHz spectral line often used for the detection of masers in circumstellar envelopes of evolved stars. As the detection of 1612 MHz OH masers in the outer shells of envelopes of these stars implies the existence of a population inversion and a high level of velocity coherence, and that these are two necessa...