Unexpectedly large mass loss during the thermal pulse cycle of the red giant star R Sculptoris
Journal article, 2012
The asymptotic giant branch star R Sculptoris is surrounded by a detached shell of dust and gas. The shell originates from a thermal pulse during which the star undergoes a brief period of increased mass loss. It has hitherto been impossible to constrain observationally the timescales and mass-loss properties during and after a thermal pulse - parameters that determine the lifetime on the asymptotic giant branch and the amount of elements returned by the star. Here we report observations of CO emission from the circumstellar envelope and shell around R Sculptoris with an angular resolution of 1.3 arcsec. What was hitherto thought to be only a thin, spherical shell with a clumpy structure, is revealed to contain a spiral structure. Spiral structures associated with circumstellar envelopes have been seen previously, from which it was concluded that the systems must be binaries. Using the data, combined with hydrodynamic simulations, we conclude that R Sculptoris is a binary system that underwent a thermal pulse approximately 1800 years ago, lasting approximately 200 years. About 0.003 Msun of mass was ejected at a velocity of 14.3 km s-1 and at a rate approximately 30 times higher than the prepulse mass-loss rate. This shows that approximately 3 times more mass is returned to the interstellar medium during and immediately after a pulse than previously thought.
Author
Matthias Maercker
European Southern Observatory (ESO)
University of Bonn
S. Mohamed
South African Astronomical Observatory
Wouter Vlemmings
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
S. Ramstedt
University of Bonn
M. A. T. Groenewegen
Royal Observatory of Belgium
E. M. Humphreys
European Southern Observatory (ESO)
F. Kerschbaum
University of Vienna
Michael Lindqvist
Chalmers, Earth and Space Sciences, Onsala Space Observatory
Hans Olofsson
Chalmers, Earth and Space Sciences, Onsala Space Observatory
C. Paladini
University of Vienna
M. Wittkowski
European Southern Observatory (ESO)
I. de Gregorio-Monsalvo
Atacama Large Millimeter-submillimeter Array (ALMA)
Lars-Åke Nyman
Atacama Large Millimeter-submillimeter Array (ALMA)
Nature
0028-0836 (ISSN) 1476-4687 (eISSN)
Vol. 490 7419 232-234Subject Categories
Astronomy, Astrophysics and Cosmology
Roots
Basic sciences
Infrastructure
Onsala Space Observatory
DOI
10.1038/nature11511