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


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 A116

Subject Categories

Astronomy, Astrophysics and Cosmology



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5/3/2018 9