Variable stars have been known to astronomers for a long time. For some, their light changes because of internal processes. OtherS have companions that eclipse them. But as the number of stars we've studied in detail has expanded, so has the number of odd ones out.
A few years ago, KIC 8462852 or Boyajian’s star (also known as Tabby's star) jumped into the spotlight. Its dips in light couldn’t be (and still aren’t) explained and the popular press jumped on passing remarks made by its discoverer Dr Tabetha Boyajian and other experts, focusing on the possibility that it might be harboring an alien megastructure. While that wasn’t the case, researchers have kept studying it to work out what’s actually behind the curious behavior.
Now a new star is also showing some odd light emission. Known as VVV-WIT-07, the star is a variable object in the plane of the Milky Way. It has experienced several dips in luminosity and a dramatic eclipse event in July 2012. An international team of astronomers has proposed several scenarios to explain what they have seen. The object may be extremely young and its light could be changing wildly. Or, it might be a well-established main sequence star with large bodies eclipsing it.
The team also put forward the idea that it could be a Mamajek’s object, or super-Saturn, an exoplanet with an extremely large disk (named after its discoverer Eric Mamajek). And last but not least it could be another Boyajian’s star. The Milky Way certainly has space for more than one extremely mysterious star.
“At present, with the information at hand, none of the proposed scenarios can be conclusively established. In any case, all of these possibilities are interesting in their own right,” the researchers wrote in their paper, published in the Monthly Notices of the Royal Astronomical Society.
While similarities with Boyajian’s star are obvious, the light changes in VVV-WIT-07 are more dramatic. Tabby's star had a dip in light that at its highest was 22 percent. The July 2012 eclipse for this new star blocked 80 percent of the light. By comparison, transiting planets tend to block a very low percentage of a star’s light when they move in front of it.
The mystery of VVV-WIT-07 will only be solved with more observations. The team suggests that if the star is orbited by something it could have a period of 170 or 322 days, so astronomers may spot something if they observe it at the right time.
The team also point out that as the survey that collected the data wasn’t actually looking for an object such as this, it's possible new surveys will find even more of these oddballs hiding in plain sight around the galaxy.