Astronomers witness possible planetary collision: 'Completely bonkers'

A distant stellar body, whose light recently began to flicker like a faltering flame, has led scientists to an amazing discovery.

Based on an analysis of the unusual changes in a star similar to the Sun, named Gaia-GIC-1, located approximately 11,600 light-years from us, its strange conduct might be best explained by two young planets colliding nearby.

"It's astonishing that various observatories caught this event directly," comments the astronomer Anastasios Tzanidakis from the University of Washington.

"There’s only a handful of other planetary collisions of any sort recorded, and none with such parallels to the impact that formed the Earth and Moon. Watching more events like this in other parts of the galaxy could inform us significantly about how planets like ours develop."

Planetary formations, especially in their budding stages, can be wildly chaotic fields. Clumps of dust develop into the first forms of planets – planetesimals – wherever environmental factors like density and gravity permit, regardless of the debris swirling around the young star.

This can result in frequent impacts, as researchers believe occurred in our own Solar System. 

In addition to later stages of intense bombardment, marked by numerous asteroid strikes on young planets, something the size of Mars is believed to have crashed into Earth, resulting in debris scattering into orbit that later created the Moon.

Finding evidence of this process happening around other stars is challenging. Planetary impacts occur on relatively diminutive scales and progress swiftly, leaving behind only short-lived (on a cosmic scale) dust clouds that are tough to spot from across the galaxy.

Nevertheless, thanks to recent extensive surveys like Gaia, astronomers are now keeping an eye on vast portions of the sky simultaneously, frequently tracking the brightness, colours, and locations of vast numbers of stars to identify any shifts in their behaviour.

For Gaia-GIC-1, changes were first noticed nearly ten years ago. It wasn't until Tzanidakis was delving into older records that he saw something unusual.

"The star’s light output appeared steady, but beginning in 2016, there were these three drops in brightness. Then, around 2021, it absolutely went off the rails," he mentions.

Gaia-GIC-1 is a star, an F-type, somewhat akin to the Sun but larger and warmer. It’s roughly 1.7 times the Sun’s width and approximately 1.3 times its weight, positioned near the southern constellation of Puppis, in the Milky Way's outer disk.

Its specific age isn't precisely measured, but it appears relatively constant, firmly settled into the main sequence. 

This indicates it has reached stellar maturity, fueled by hydrogen fusion within its core. F-type stars are generally stable – they aren't known for the vibrant activity seen in red dwarf stars, nor do they exhibit the unusual changes characteristic of stars nearing the end of their lifespans, like Betelgeuse.