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Rings and filaments: The remarkable detached CO shell of U Antliae

F. Kerschbaum ; Matthias Maercker (Institutionen för rymd-, geo- och miljövetenskap, Astronomi och plasmafysik) ; M. Brunner ; Michael Lindqvist (Institutionen för rymd-, geo- och miljövetenskap, Onsala rymdobservatorium) ; Hans Olofsson (Institutionen för rymd-, geo- och miljövetenskap, Astronomi och plasmafysik) ; M. Mecina ; Elvire De Beck (Institutionen för rymd-, geo- och miljövetenskap, Astronomi och plasmafysik) ; M. A. T. Groenewegen ; E. Lagadec ; S. Mohamed ; C. Paladini ; S. Ramstedt ; Wouter Vlemmings (Institutionen för rymd-, geo- och miljövetenskap, Astronomi och plasmafysik) ; M. Wittkowski
Astronomy and Astrophysics (0004-6361). Vol. 605 (2017),
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: stars: AGB and post-AGB, stars: carbon, stars: evolution, stars: mass-loss



Denna post skapades 2017-11-07. Senast ändrad 2017-11-07.
CPL Pubid: 252968

 

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