相关论文: Structure and shaping processes within the extende…
We report on recent observations of AGB stars obtained with the VLT Interferometer (VLTI). We illustrate in general the potential of interferometric measurements to study stellar atmospheres and circumstellar envelopes, and demonstrate in…
Encoded in the time- and wavelength dependent properties of pulsating AGB stars are the underlying fundamental parameters of mass, composition and evolutionary state. However, the standard technique of placing stars on a HR diagram, even…
We investigate the observable characteristics of the extended atmospheres of AGB stars across a wide range of radio and (sub-)mm wavelengths using state-of-the-art 1D dynamical atmosphere and wind models over one pulsation period. We also…
Aims. We aim to explore the photosphere of the very cool late-type star VX Sgr and in particular the existence and characterization of molecular layers above the continuum forming photosphere. Methods. We obtained interferometric…
We study the circumstellar environment of the M-type AGB star RT Vir using mid-infrared high spatial resolution observations from the ESO-VLTI focal instrument MIDI. The aim of this study is to provide observational constraints on…
Radio and infrared interferometry of SiO maser stars provide complementary information on the atmosphere and circumstellar environment at comparable spatial resolution. Here, we present the latest results on the atmospheric structure and…
We present a near-infrared spectro-interferometric observation of the non-Mira-type, semiregular asymptotic giant branch star SW Vir. Our aim is to probe the physical properties of the outer atmosphere with spatially resolved data in…
We investigate the molecular and dusty environment of OH/IR stars in order to characterize the mass-loss process during the tip-AGB superwind phase. Employing the AMBER instrument at the VLT Interferometer we obtained near-infrared H- and…
The initial conditions for the mass loss during the asymptotic giant branch (AGB) phase are set in their extended atmospheres, where, among others, convection and pulsation driven shocks determine the physical conditions. High resolution…
The knowledge of the structure and dynamics of AGB-star atmospheres is crucial to better understand the mass loss. The tomographic method, that relies on the design of spectral masks containing lines forming in given ranges of optical…
The mechanism of mass loss in late evolutionary stages of low- and intermediate-mass stars is not yet well understood. Therefore, it is crucial to study the dynamics of the region within a few stellar radii, where the wind acceleration is…
The mass loss experienced on the asymptotic giant branch (AGB) at the end of the lives of low- and intermediate-mass stars is widely accepted to rely on radiation pressure acting on dust grains formed in the extended AGB atmospheres. The…
We have used near- and mid-infrared interferometry to investigate the pulsating atmosphere and the circumstellar environment of the Mira variable RR Aql. Observations were taken with the VLTI/AMBER (near infrared) and the VLTI/MIDI (mid…
With the construction of the VLTI (Very Large Telescope Interferometer of the European Observatory ESO for the southern hemisphere) it is now possible to make observations with resolutions of the order of milli-arc-seconds, especially in IR…
The atmospheres of evolved red giants are considerably influenced by pulsations of the stellar interiors and developing stellar winds. The resulting complex velocity fields severely affect molecular line profiles observable in NIR spectra.…
We present astrometric very long baseline interferometry (VLBI) studies of AGB stars. To understand the properties and evolution of AGB stars, distances are an important parameter. The distribution and kinematics of their circumstellar…
We report on our project of coordinated VLTI/VLBA observations of the atmospheres and circumstellar environments of evolved stars. We illustrate in general the potential of interferometric measurements to study stellar atmospheres and…
Modeling stellar atmospheres is a complex, intriguing task in modern astronomy. A systematic comparison of models with multi-technique observations is the only efficient way to constrain them. Aims: We performed a self-consistent modeling…
We report the results of an exploratory program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered galactic light. The goal is to characterize the morphology of the envelopes as a probe of…
Differential phase observations with a near-IR interferometer offer a way to obtain spectra of extrasolar planets. The method makes use of the wavelength dependence of the interferometer phase of the planet/star system, which depends both…