ALMA observations of the "fresh" carbon-rich AGB star TX Piscium. The discovery of an elliptical detached shell

Aims. The carbon-rich asymptotic giant branch (AGB) star TX Piscium (TX Psc) has been observed multiple times during multiple epochs and at different wavelengths and resolutions, showing a complex molecular CO line profile and a ring-like structure in thermal dust emission. We investigate the molecu...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2018-11
Main Authors: Brunner, Magdalena, Mecina, Marko, Maercker, Matthias, Dorfi, Ernst A, Kerschbaum, Franz, Olofsson, Hans, Rau, Gioia
Format: Article
Language:English
Subjects:
Asymptotic giant branch stars
Carbon
Detaching
Dust
Ellipticity
Emission analysis
Identification methods
Momentum transfer
Radio telescopes
Stellar rotation
Velocity distribution
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Aims. The carbon-rich asymptotic giant branch (AGB) star TX Piscium (TX Psc) has been observed multiple times during multiple epochs and at different wavelengths and resolutions, showing a complex molecular CO line profile and a ring-like structure in thermal dust emission. We investigate the molecular counterpart in high resolution, aiming to resolve the ring-like structure and identify its origin. Methods. Atacama Large Millimeter/submillimeter Array (ALMA) observations have been carried out to map the circumstellar envelope (CSE) of TX Psc in CO(2-1) emission and investigate the counterpart to the ring-like dust structure. Results. We report the detection of a thin, irregular, and elliptical detached molecular shell around TX Psc, which coincides with the dust emission. This is the first discovery of a non-spherically symmetric detached shell, raising questions about the shaping of detached shells. Conclusions. We investigate possible shaping mechanisms for elliptical detached shells and find that in the case of TX Psc, stellar rotation of 2 km/s can lead to a non-uniform mass-loss rate and velocity distribution from stellar pole to equator, recreating the elliptical CSE. We discuss the possible scenarios for increased stellar momentum, enabling the rotation rates needed to reproduce the ellipticity of our observations, and come to the conclusion that momentum transfer of an orbiting object with the mass of a brown dwarf would be sufficient.
ISSN:2331-8422
DOI:10.48550/arxiv.1811.07577