Astronomers using NASA's Spitzer Space Telescope have spotted a star ripping through space, generating a violent bow shock ahead of its relentless rampage through the interstellar medium.
Kappa Cassiopeiae (κ Cass) is a hypervelocity blue supergiant star over 40 times the size of our sun that is barreling through space at the breakneck speed of 2.5 million miles per hour (or 1,100 kilometers per second) relative to its neighboring stars. At those kinds of velocities, you'd expect to see something dramatic and κ Cass doesn't disappoint.
Spitzer's infrared optics have picked out κ Cass' huge bow shock as the star's magnetic field and stellar wind particles slam into the gases and dust filling the interstellar medium, heating it up. Bow shocks are often found in front of some of the speediest stars in our galaxy.
Bow shocks are useful as they act as a remote sensor of sorts, allowing astronomers to understand the characteristics of the environment the star is traveling through.
In this image, the red bow shock exhibits some fine structure that is possibly linked to the magnetic field that threads throughout the Milky Way shaping the gas and dust. By zooming in on these hypervelocity stars that sport bow shocks, astronomers are allowed a rare look into the structure of this normally invisible field that is thought to permeate our entire galaxy.
The wispy green clouds throughout the image are caused by polycyclic aromatic hydrocarbons illuminated by starlight that are located along Spitzer's line of sight to κ Cass.
This observation may be a valuable probe into the conditions surrounding a star 4,000 light-years away, but it also serves as a stunning example on the scale of the supergiant's sphere of influence. The distance from the star to bow shock covers a vast 4 light-years -- the approximate distance from our sun to neighboring star Proxima Centauri.