Betelgeuse creates a splash

Akari observations of Betelgeuse, a bright red supergiant star located in the constellation Orion about 640 light-years from Earth, show the star making a big splash by creating a bow shock as it crosses the interstellar medium.

This is a three-colour composite image of Betelgeuse and its surroundings is composed of images taken at at 65 (blue), 90 (green) and 140 (red) micrometers taken by Akari's Far-Infrared Surveyor FIS.

The arc-like structure to the upper left direction of the star is the bow shock formed due to collision of stellar wind and the interstellar matter in the direction of the star's motion (from lower left to upper right). The diameter of the bow shock is about three light-years. The blue-white linear structure from lower left to upper right through the star is an effect of the instrument.

Researchers have found a strong flow of the interstellar medium around the star which originates from star-forming regions in Orion's Belt and has a velocity of 11 km/s. Betelgeuse is crossing this river at 30 km/s, while spewing out wind at 17 km/s.