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: mass-loss

stars: AGB and post-AGB

stars: evolution


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

University of Cape Town

South African Astronomical Observatory

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 A116


Astronomi, astrofysik och kosmologi