Rings and filaments: The remarkable detached CO shell of U Antliae
Artikel i vetenskaplig tidskrift, 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
Författare
F. Kerschbaum
Universität Wien
Matthias Maercker
Astronomi och plasmafysik
M. Brunner
Universität Wien
Michael Lindqvist
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
Hans Olofsson
Astronomi och plasmafysik
M. Mecina
Universität Wien
Elvire De Beck
Astronomi och plasmafysik
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 universitet
Wouter Vlemmings
Astronomi och plasmafysik
M. Wittkowski
European Southern Observatory (ESO)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 605 A116Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/201730665