Strange dips in the light from Tabby’s Star have been puzzling scientists since 2015, with some hopefuls refusing to rule out the chance that some kind of “alien megastructure” could be blocking the way.
Experts have now come up with another explanation that doesn’t involve extraterrestrial technology, but rather a massive ringed planet some five times the size of Jupiter.
Astronomers from the University of Valencia and the University of Cantabria in Spain ran a giant planet model and found it could account for some of the light fluctuations if the planet’s rings were tilted.
Other dips in light that scientists have recorded since could be caused by trailing asteroids, the team says.
If the hypothesis is right, then we’re going to see another dip in light in 2021 thanks to a second cloud of asteroids, as these swarms usually travel in pairs – so we need to keep our telescopes trained at the stars.
“We aim at offering a relatively natural solution, invoking only phenomena that have been previously observed, although perhaps in larger or more massive versions,” the astronomers write in their paper.
Tabby’s Star, technically known as KIC 8462852, is more massive and hotter than our Sun, and can be found almost 1,500 light-years away between the Cygnus and Lyra constellations of the Milky Way.
We’ve known about it since 2009, but a couple of years ago the star became something of a stellar celebrity after astronomers noted dips in light that were far more frequent and irregular than they should be.
Since then, more variations in the emitted light have been spotted, with the most recent just last month. That particular dip could be caused by the giant planet passing behind Tabby’s Star, say the researchers responsible for the new hypothesis.
That would dim the total amount of light coming from the system, as there would be no visible reflection off the planet as it passed behind the star.
If we’re not dealing with alien spaceships or a huge planet the size of five Jupiters, space junk could also be responsible, according to a 2016 study.
That study put forward the idea that a different star along our line of sight, together with an unidentified form of space clutter, could be causing the dimming.
For now, the idea of planetary rings and asteroids is just a hypothesis, and it hasn’t yet been peer-reviewed or published in a journal. The astronomers behind it have put their study online at arXiv.org to get feedback from the wider scientific community.
Not everyone is convinced, however: David Kipping from Columbia University says that the biggest issue is the way the model scales.
“It’s great that we’re getting creative and maybe some parts of this theory might comprise the final answer, but I’m fairly sceptical this is the solution,” Kipping told Shannon Hall at New Scientist.
The study authors aren’t too deterred though: they say that although there are problems with how the idea scales, large parts of the hypothesis fit the data we’ve got.
“Whatever the solution to the riddle, it’s going to be exciting,” one of the researchers, Alberto Fernández-Soto, told New Scientist.
In 2021, we might get chance to see if Fernández-Soto and his colleagues are right.
You can see the paper for yourself at the pre-print website arXiv.org.