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

Abstract

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 years 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 $\approx$ 10${}^{-5}$ $M_{\odot }$ 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$\times$10${}^{-8}$ $M_{\odot }$ yr${}^{-1}$, at present being consistent with evolutionary changes as predicted for the period between thermal pulses.

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Cited by in corpus (14)

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• Properties of dust in the detached shells around U Ant, DR Ser, and V644 Sco
• The Nearby Evolved Stars Survey: I. JCMT/SCUBA-2 Sub-millimetre detection of the detached shell of U Antliae
• Faint but not forgotten. I. First results from a search for astrospheres around AGB stars in the far-ultraviolet
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• Extended far-UV emission surrounding asymptotic giant branch stars as seen by GALEX
• Probing the dynamical and kinematical structures of detached shells around AGB stars
• Discovery of a brown dwarf with quasi-spherical mass-loss
• Extended view on the dust shells around two carbon stars
• X TrA through the eyes of MATISSE: More evidence of clumpy molecular layers around C-type asymptotic giant branch stars
• Detached Shell Carbon Stars: Tracing Thermal Pulses on the Asymptotic Giant Branch
• Variability in SSTc2d J163134.1-240100, a brown dwarf with quasi-spherical mass loss