Stellar Astrophysics

An expanding shell around an evolved star

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Science  06 Oct 2017:
Vol. 358, Issue 6359, pp. 77-78
DOI: 10.1126/science.358.6359.77-g

When intermediate-mass stars approach the ends of their lifetimes, they begin to shed their outer layers. Bursts of nuclear reactions in the stellar core lead to thermal pulses, temporarily increasing the mass-loss rate for several centuries. Kerschbaum et al. have mapped the carbon monoxide gas ejected by the nearby evolved star U Antliae. The gas forms an almost perfectly symmetric expanding shell around the star. By measuring the velocity of the expansion, the authors calculated how the mass-loss rate has changed over several thousand years and showed that it agrees with models of thermal pulses. The results will help to understand how evolved stars enrich the interstellar medium with heavy elements.

Astron. Astrophys. 605, A116 (2017).

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