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The carbon star R Sculptoris sheds its skin

Published online by Cambridge University Press:  30 December 2019

Markus Wittkowski*
Affiliation:
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany, email: [email protected]
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Abstract

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We describe near-IR H-band VLTI-PIONIER aperture synthesis images of the carbon AGB star R Sculptoris with an angular resolution of 2.5 mas. The data show a stellar disc of diameter ∼ 9 mas exhibiting a complex substructure including one dominant bright spot with a peak intensity of 40% to 60% above the average intensity. We interpret the complex structure as caused by giant convection cells, resulting in large-scale shock fronts, and their effects on clumpy molecule and dust formation seen against the photosphere at distances of 2–3 stellar radii. Moreover, we derive fundamental parameters of R Scl, which match evolutionary tracks of initial mass 1.5 ± 0.5 M. Our visibility data are best fit by a dynamic model without a wind, which may point to problems with current wind models at low mass-loss rates.

Type
Contributed Papers
Copyright
© International Astronomical Union 2019 

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