We report the detection of an H i counterpart to the extended, far-ultravioletemitting tail associated with the asymptotic giant branch star Mira (o Ceti). Using the Nançay Radio Telescope (NRT), we have detected emission as far as 88 north of the star, confirming that the tail contains a significant atomic component (MHI ∼ 4× 10 −3 M⊙). The NRT spectra reveal a deceleration of the tail gas cau...

We present numerical hydrodynamical models of the effects of planets or brown dwarfs orbiting within the extended atmosphere and wind formation zone of Mira variables. We find time-dependent wake dynamics and episodic accretion phenomena which may give rise to observable optical events and affect SiO maser emission. Subject headings: stars: planetary systems stars: winds, outflows stars: variab...

Asymmetries and motions in the dust shell surrounding Mira A (o Ceti) are reported. Measurements were taken with the UCBerkeley Infrared Spatial Interferometer (ISI), a three-element interferometer operating at 11.15 m. At the time of these observations, it was in a linear, east-west configuration with a maximum baseline of 12 m and thus had a resolution of better than 100mas. Three years of da...

We carried out a new and sensitive search for long-period variability in the prototype of the Mira class of long-period pulsating variables, o Ceti (Mira A), the closest and brightest Mira variable. We conducted this search using an unbroken light curve from 1902 to the present assembled from the visual data archives of five major variable star observing organizations from around the world. We ...

We present ultraviolet spectra of Mira’s companion star from the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). The companion is generally assumed to be a white dwarf surrounded by an accretion disk fed by Mira’s wind, which dominates the UV emission from the system. The STIS UV spectrum is dominated by numerous, narrow H2 lines fluoresced by H...

We present new Far Ultraviolet Spectroscopic Explorer (FUSE) observations of Mira A’s wind-accreting companion star, Mira B. We find that the strongest lines in the FUSE spectrum are H2 lines fluoresced by H I Lyα. A previously analyzed Hubble Space Telescope (HST) spectrum also shows numerous Lyα-fluoresced H2 lines. The HST lines are all Lyman band lines, while the FUSE H2 lines are mostly We...

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.

A general review is given of Mira and some other cool variables stars, concentrating on those aspects on which GAIA, and more particularly GAIA spectroscopy and radial velocities, will have a major impact.

We analyze the K band luminosities of a sample of galactic long-period variables using parallaxes measured by the Hipparcos mission. The parallaxes are in most cases re-computed from the Hipparcos Intermediate Astrometric Data using improved astrometric fits and chromaticity corrections. The K band magnitudes are taken from the literature and from measurements by COBE, and are corrected for int...

We have observed the intermediate regions of the circumstellar envelope of Mira (o Ceti) in photospheric light scattered by three vibration-rotation transitions of the fundamental band of CO, from low-excited rotational levels of the ground vibrational state, at an angular distance of β ∼ 2 − 7 away from the star. The data were obtained with the Phoenix spectrometer mounted on the 4 m Mayall te...