Thibaut Le Bertre

On the central symmetry of the circumstellar envelope of RS Cnc

We present a phenomenological study of CO(1-0) and CO(2-1) emission from the circumstellar envelope (CSE) of the Asymptotic Giant Branch (AGB) star RS\,Cnc. It reveals departures from central symmetry that turn out to be efficient tools for the exploration of some of the CSE properties. We use a wind model including a bipolar flow with a typical wind velocity of

Mass Loss Characteristics of Dust Forming Long-Period Variable Stars

\sim

Infrared appearance of dust forming LPVs

8 km\,s

Optical Appearance of Dynamical Models for Circumstellar Dust Shells around Long-Period Variables: AFGL 3068

^{-1}

HI Mapping Of The Circumstellar Environment Of X Her: An AGB Star Associated With A High-Velocity Cloud?

decreasing to

HI and CO study of circumstellar environments

\sim

AGB Circumstellar Environments Probed through 21-cm Atomic Hydrogen Emission

2 km\,s

HI in circumstellar envelopes around AGB stars: Observations and modelling of the detached shell around the carbon star Y CVn

^{-1}

AGB circumstellar environments probed through the 21 cm atomic hydrogen line emission. A programme for the SKA

near the equator to describe Doppler velocity spectral maps obtained by merging data collected at the IRAM Plateau de Bure Interferometer and Pico Veleta single dish radio telescope. Parameters describing the wind morphology and kinematics are obtained, together with the radial dependence of the gas temperature in the domain of the circumstellar envelope probed by the CO observations. Significant north-south central asymmetries are revealed by the analysis, which we quantify using a simple phenomenological description. The origin of such asymmetries is unclear.

Some difficulties related to the detection of circumstellar atomic hydrogen

We present results obtained from a grid of model calculations for dust forming circumstellar shells around carbon-rich long-period variable stars. These models consistently treat the time-dependent hydrodynamics, chemistry, dust formation and the radiative transfer problem. We show that variations of the mass loss rates observed on different time scales are well reproduced by our models.