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 artist’s impression shows how the bow shock structure is oriented with respect to Betelgeuse, the flow of the interstellar medium, and the Earth.
A discontinuity in density and pressure appears at the boundary where stellar wind from Betelgeuse collides into interstellar matter. Betelgeuse moves in space from lower right to upper left in this figure.
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.