A new view of two very well-known galaxies has revealed they are connected by faint, starless filaments of hydrogen gas, which trace back to a very high-speed intergalactic collision.

The smash-up between M86 and NGC4438 had not been suspected before, and may explain why M86, which is visible to the naked eye, is unable to give birth to new stars.

"Stars and gases behave very differently in collisions," says astronomer Professor Jeffrey Kenney of Yale University and lead author of a paper in the November 2008 issue of Astrophysical Journal Letters.

During galactic smash-ups stars rarely collide, since there is so much space between them. But gases do slam into gases. The faster the collision, the higher the temperature the gases reach.

In the case of M86, its gases are millions of degrees in temperature and radiate x-rays.

The new evidence of M86's collision may solve that mystery. What's more, the super-hot gas also probably explains why M86 is unable to produce new stars.