Hottest Stars in Delicate Embrace by Spiral Arms
Artist's impression of large spiral waves around massive hot star HD 64760. Bright spots at the star's surface create delicate gas density enhancements winding up in the plane of the equator. Credit: Alex Lobel/Ronny Blomme, Royal Observatory of Belgium.
Supercomputer simulation of the gas density around massive hot star HD 64760 in the constellation of Puppis. The image shows the density contrast computed for two unequally bright spots rotating over the surface of the star in the plane of the equator. The wind slows down inside these large-scale counter-clockwise rotating spiral arms where the density contrast is largest (shown in green, yellow, and red colors). Wind particles expelled by the star follow almost straight radial paths outwards. When they cross the spirals radially the particles temporarily decelerate with respect to the surrounding wind, thereby enhancing the local wind density. Extra mass from the bright surface spots creates two stable spiral arms through which the surrounding fast wind streams (pale and dark blue colors). Credit: Ronny Blomme, Royal Observatory of Belgium.
