The End: Witnessing the Death of Extreme Carbon Stars

G.C. Sloan (STScI, UNC), K.E. Kraemer (Boston Coll.), I. McDonald, & A.A. Zijlstra (Univ. of Manchester)

2019, in IAU Symp. 343 - Why galaxies care about AGB stars: A continuing challenge through cosmic time, ed. F. Kerschbaum, M.A.T. Groenewegen, & H. Olofsson, in press

Full manuscript available locally (PDF)

A small number of the sample of 184 carbon stars in the Magellanic Clouds show signs that they are in the act of evolving off of the asymptotic giant branch. Most carbon stars grow progressively redder in all infrared colors and develop stronger pulsation amplitudes as their circumstellar dust shells become optically thicker. The reddest sources, however, have unexpectedly low pulsation amplitudes, and some even show blue excesses that could point to deviations from spherical symmetry as they eject the last of their envelopes. Previously, all dusty carbon-rich AGB stars have been labeled “extreme,” but that term should be reserved for the truly extreme carbon stars. These objects may well hold the clues needed to disentangle what actually happens when a star ejects the last of its envelope and evolves off of the AGB.

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Last modified 4 January 2019. © Gregory C. Sloan and others.