This misbehaving black hole spits out star stuff

Contributed by
Jan 30, 2017

Space may often seem to be a vast void of darkness and silence, but there is apparently astral misbehavior going on right in our galaxy. The supermassive black hole lurking in the center of the Milky Way only comes off as quiet — until it acts up every 10,000 years and launches spitballs made of star stuff.

This troublemaker that clearly has no regard for cosmic classroom rules is the result of tidal disruption, a phenomenon in which a star-crossed star that wanders too close to a black hole's event horizon is ruthlessly ripped to shreds by the intense pull of its tidal gravitational forces. Chaos ensues as the star is mutilated and half of its mass is ravenously consumed while the other half is flung out.

As the swirling gases that were the star's innards spiral into orbit around the black hole, some of the astral gore is forcibly flung out far away enough from the intense gravity that it falls apart and regroups into around a hundred glowing planet-size globs that shoot into space at up to 20 million mph.

Mischief like this doesn't just happen in the Milky Way. Andromeda fires them right back at us. Black holes reside at the cores of most other galaxies, and once they catapult fiery projectiles at such incredible speeds, most zoom far beyond their galaxy.

Rogue behavior doesn't make these disembodied stellar fragments rogue planets. While they could pass for planetary rogues in the eye of a telescope -- and usually range in size from Neptune to Jupiter -- they're anything but. Planets take millions of years to come into being. These fireballs form within about a year after their stars are mangled by black holes and are made mostly of the hydrogen and helium that fueled those stars. Their chemical composition is also inconsistent; since they are Frankenstein-esque objects reanimated from different parts of the same destroyed star, one can be drastically different from the other on a molecular level.

Proving that these elusive objects really are hurtling through space somewhere is the obsession of Eden Girma. With her colleagues at the Harvard Smithsonian Center for Astrophysics (CfA), the Harvard undergrad and team lead developed a computer code that simulated their trajectories to determine where exactly they are whizzing by and whether they dare approach our planet. Simulations revealed that the majority of them not only rocket out of the Milky Way, but end up anywhere from 700 to 10 million light years away. It would take approximately a million years from the time of ejection for one to reach the vicinity of Earth even at a supernatural speed. Meaning, none will be crashing into us any time soon.   

Girma is cautiously optimistic that we will soon be able to see the spitballs in action. Even though these far-off infrared globes would fade considerably during their million-year journeys toward us as they cooled off (infrared radiation emissions issue from heated objects), upcoming advanced telescopes such as the James Webb Space Telescope and the Large Synoptic Survey Telescope may be able to identify them as soon as next year — if one actually crosses its field of vision.

"Only about one out of a thousand free-floating planets will be one of these second-generation oddballs," observed Girma. Even though the fireballs that linger in the Milky Way are relatively rare -- not to mention difficult to tell apart from rogue planets meandering around our galaxy -- capturing an image of one is not impossible. Future technology may just spot a space oddity.

(via AstronomyNow)