Updated

Updated · Space.com · Jun 22

Red Giants Get 10,000 Plasma Kicks, Driving 2,200 mph Random Walk Before White Dwarf Stage

Updated

Updated · Space.com · Jun 22

Red Giants Get 10,000 Plasma Kicks, Driving 2,200 mph Random Walk Before White Dwarf Stage

Q: As dying suns get 'kicked' across space, what are the odds they will collide with another star before they burn out?

The odds are extremely low for a dying Sun-like star to hit a random, unrelated star before it finishes becoming a white dwarf. Even with the newly proposed “kicks,” the speeds involved are modest by galactic standards — about 2,200 mph, or roughly 1 kilometer per second — and space between stars is vast. What Fuller’s work really changes is not the chance of random collisions in open space, but the behavior of stars already in binary systems. The model suggests that repeated asymmetric mass ejections during the red-giant phase can gradually alter a star’s orbit through a random walk. In many cases that may simply loosen or break apart wide binaries, which matches earlier evidence showing a shortage of widely separated systems containing a white dwarf. The more interesting collision risk is with a pre-existing companion. In some cases, the kicks could push a red giant onto a collision course with the star it is already orbiting, potentially producing a violent merger or explosion. That is a specific prediction of the model, but it has not yet been observed, and the study does not give a firm numerical probability. Outside dense environments such as galactic centers or crowded clusters, direct star-star collisions remain rare. So the practical answer is that a kicked dying Sun is very unlikely to crash into a random star, but it may, in uncommon cases, be nudged into its own companion if it is part of a binary.

1 articles · Updated · Space.com · Jun 22

Jim Fuller calculated that sun-like stars in their red giant phase are jolted about 10,000 times by asymmetric plasma ejections, producing a net "random walk" at roughly 2,200 mph before they become white dwarfs.
The mechanism is repeated recoil: each blob of plasma blasted from the bloated star pushes it slightly the other way, and those chaotic kicks accumulate over hundreds of thousands of years into measurable motion.
That motion could explain why wide binary systems are rarer after one star turns into a white dwarf, because kicks faster than the pair's orbital speed can gravitationally unbind the stars.
Fuller's model also predicts rarer cases in which a kicked red giant is driven into a stellar companion and explodes, giving astronomers a possible new target to test the idea.