47 citations · 252 across the 15 of their papers we have counts for
8 papers · 1 filter
The loss of large amplitude pulsations at the end of AGB evolution
Dieter Engels, Sandra Etoka, Eric Gerard
Since 2013 we are performing with the Nancay Radio Telescope (NRT) a monitoring program of >100 Galactic disk OH/IR stars, having bright 1612-MHz OH maser emission. The variations…
Distances of Stars by mean of the Phase-lag Method
Sandra Etoka, Dieter Engels, Eric Gerard +1
Variable OH/IR stars are Asymptotic Giant Branch (AGB) stars with an optically thick circumstellar envelope that emit strong OH 1612 MHz emission. They are commonly observed throug…
HI emission from the red giant Y CVn with the VLA and FAST
D. T. Hoai, P. T. Nhung, L. D. Matthews +2
Imaging studies with the VLA have revealed HI emission associated with the extended circumstellar shells of red giants. We analyse the spectral map obtained on Y CVn, a J-type carb…
Phase-lag Distances of OH Masing AGB Stars
D. Engels, S. Etoka, E. Gerard +1
Distances to AGB stars with optically thick circumstellar shells cannot be determined using optical parallaxes. However, for stars with OH 1612 MHz maser emission emanating from th…
Discovery of a Shell of Neutral Atomic Hydrogen Surrounding the Carbon Star IRC+10216
L. D. Matthews, E. Gerard, T. Le Bertre
We have used the Robert C. Byrd Green Bank Telescope to perform the most sensitive search to date for neutral atomic hydrogen (HI) in the circumstellar envelope (CSE) of the carbon…
An HI Imaging Survey of Asymptotic Giant Branch Stars
L. D. Matthews, T. Le Bertre, E. Gerard +1
We present an imaging study of a sample of eight asymptotic giant branch (AGB) stars in the HI 21-cm line. Using observations from the Very Large Array, we have unambiguously detec…
An HI 21-cm line survey of evolved stars
E. Gerard, T. Le Bertre, Y. Libert
The HI line at 21 cm is a tracer of circumstellar matter around AGB stars, and especially of the matter located at large distances (0.1-1 pc) from the central stars. It can give un…
HI Observations of the Asymptotic Giant Branch Star X Herculis: Discovery of an Extended Circumstellar Wake Superposed on a Compact High-Velocity Cloud
L. D. Matthews, Y. Libert, E. Gerard +3
We report HI 21-cm line observations of the AGB star X Her obtained with the Green Bank Telescope (GBT) and the Very Large Array (VLA). We have detected HI emission totaling M_HI=2…