Astronomy: A turbulent stellar atmosphere in full view.

Abstract

The dynamic motion of gas in the outer atmosphere of a red supergiant star has been mapped, providing clues to the mysterious mechanism that causes massive stars to lose mass through stellar winds. See Letter p.310 Red supergiant stars are at a late evolutionary stage for stars. The initial masses of these stars are greater than nine solar masses. Red supergiant stars have complex, multi-component atmospheres, which have been studied spectroscopically. Here, Keiichi Ohnaka et al. report data from spectral imaging of the surface and atmosphere of the red supergiant star Antares. The team found large clumps of gas moving up and down the atmosphere at speeds of up to 20 kilometres per second. Convection is not sufficient to explain these motions, which leads the authors to suggest that an unknown process is operating in the star's extended atmosphere.