Rings and filaments: The remarkable detached CO shell of U Antliae
Journal article, 2017
Aims. Our goal is to characterize the intermediate age, detached shell carbon star U Antliae morphologically and physically in order to study the mass-loss evolution after a possible thermal pulse. Methods. High spatial resolution ALMA observations of unprecedented quality in thermal CO lines allow us to derive first critical spatial and temporal scales and constrain modeling efforts to estimate mass-loss rates for both the present day as well as the ejection period of the detached shell. Results. The detached shell is remarkably thin, overall spherically symmetric, and shows a barely resolved filamentary substructure possibly caused by instabilities in the interaction zone of winds with different outflow velocities. The expansion age of the detached shell is of the order of 2700 yr and its overall width indicates a high expansion-velocity and high mass-loss period of only a few hundred years at an average mass-loss rate of approximate to 10(-5) M-circle dot yr(-1). The post-high-mass-loss-rate-epoch evolution of U Ant shows a significant decline to a substantially lower gas expansion velocity and a mass-loss rate amounting to 4 x 10(-8) M-circle dot yr(-1), at present being consistent with evolutionary changes as predicted for the period between thermal pulses.
stars: carbon
stars: AGB and post-AGB
stars: evolution
stars: mass-loss
Author
F. Kerschbaum
University of Vienna
Matthias Maercker
Astronomy and Plasmaphysics
M. Brunner
University of Vienna
Michael Lindqvist
Chalmers, Earth and Space Sciences, Onsala Space Observatory
Hans Olofsson
Astronomy and Plasmaphysics
M. Mecina
University of Vienna
Elvire De Beck
Astronomy and Plasmaphysics
M. A. T. Groenewegen
Royal Observatory of Belgium
E. Lagadec
Observatoire de la Cote d'Azur
S. Mohamed
National Institute for Theoretical Physics
South African Astronomical Observatory
University of Cape Town
C. Paladini
Université libre de Bruxelles (ULB)
S. Ramstedt
Uppsala University
Wouter Vlemmings
Astronomy and Plasmaphysics
M. Wittkowski
European Southern Observatory (ESO)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 605 A116Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201730665