The traditional definition of a planet is “celestial wanderer,” a solid or gaseous body orbiting the Sun that moves against the seemingly fixed stars. In the 1990s, we added exoplanets to the mix. Now, we’ve got a new planetary black sheep in our own cosmic backyard. Using the ESO’s Very Large Telescope and the Canada-France-Hawaii Telescope, astronomers have found what looks to be a planet wandering star-less through space. If further study of the data confirm its planetary status, the body might be one of the most significant objects we’ve found to date.
Free floating planets are oddballs. This latest one discovered, called CFBDSIR2149, is no exception. It isn’t the first free planet we’ve found, but it’s got some interesting qualities that make it so interesting.
Typical of rogue planets, CFBDSIR2149 is without a parent star. This is excellent for observations. When astronomers look at exoplanets, trying to determine their size, mass, and composition, they’re basically staring into a bright light source. Separating the planet’s data can be tough. But without a star there’s no pesky bright light throwing off their observations. It’s likely that astronomers will be able to get a good look at CFBDSIR2149. They should be able to determine its characteristics pretty well and then apply the lessons learned to future exoplanet study.
CFBDSIR2149’s proximity to Earth is another interesting feature of the rogue planet that will be a big help to astronomers. The planet is less than 100 light years away from Earth, making it the closest free-range planet to our solar system.
CFBDSIR2149 is the pale, dark blue dot in the centre of this image, captured by
the SOFI instrument on ESO’s New Technology Telescope at the La Silla Observatory
But that’s not all. Astronomer’s suspect CFBDSIR2149 might be part of a cluster or stream of young stars known to meander through the same part of space called the AB Doradus Moving Group. Like the rogue planet, this group is the closest of its kind to the Solar System.
AB Doradus is a series of about 30 stars drifting through space together. They are thought to have formed at the same time and not too long ago; astronomers estimate the average age in the pack is less than 200 million years old, far younger than the Sun’s 4.6 billion years. Objects this young tend to have some residual heat from their formation, making them easier to spot in the infrared end of the spectrum. Looking in the infrared is how astronomers found the wandering CFBDSIR2149.
If the rogue planet does turn out to be associated with AB Doradus, astronomers will know its a young object. They will also be able to extrapolate some details about the planet based on the characteristics of its pack including temperature, mass, and its atmospheric composition. There’s a small possibility that CFBDSIR2149 has joined up with AB Doradus by chance, but its too early to rule out the possibility that they’re somehow connected. Besides, it’ll be more interesting if the planet is part of the group. It will be the first solid mass body every found in a moving group, adding to its intrigue.
We’ve only been talking about real exoplanets for 20 years, and to find some that aren’t attached to stars is just wacky. It’s like something out of a sci-fi movie, though probably now a sentient celestial wanderer like Ego the Living Planet. And for all the doomsday theorists, it’s worth reinforcing that CFBDSIR2149 is about 100 light years away from Earth. It’s way too far to cause the Nibiru cataclysm, the destruction of Earth by a rogue planet predicted to happen sometime in the early 21st century (say, on December 21, 2012). Whatever CFBDSIR2149 turns out to be, it’s highly unlikely “harbinger of doom to the Earth” will be on its bio sheet.