The most mysterious star in the universe is finally revealing some of its secrets. Thanks to a successful Kickstarter campaign and the work of over 200 researchers, it is possible to say that the curious light dips of Tabby’s Star are definitely not caused by an alien megastructure.
The star was observed regularly between March 2016 and December 2017, and after May 2017 four light dips were detected, the first since the originals seen by planet-hunter telescope Kepler. The dips in the light of the star had different intensities at different wavelengths, indicating that whatever the cause, it couldn’t have been a solid object. The research is reported in the Astrophysical Journal Letters.
“Dust is most likely the reason why the star’s light appears to dim and brighten," lead author and the star's discoverer Dr Tabetha Boyajian, from whom it takes its nickname, said in a statement. "The new data shows that different colors of light are being blocked at different intensities. Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure.”
The team used the Las Cumbres Observatory and were able to collect the largest amount of data yet on this object. And while they could reject the alien megastructure hypothesis, there is no definitive answer to what’s causing the dips in brightness.
“This latest research rules out alien megastructures, but it raises the probability of other phenomena being behind the dimming,” co-author Jason Wright, an assistant professor at Penn State University, explained. “There are models involving circumstellar material – like exocomets, which were Boyajian’s team’s original hypothesis – which seem to be consistent with the data we have. Some astronomers favor the idea that nothing is blocking the star – that it just gets dimmer on its own – and this also is consistent with this summer’s data.”
Four dips were observed over the summer and the contributors to the Kickstarter voted on the names, with the first two called Elsie and Celeste and the latter two named after two ancient lost cities, Scotland’s Skara Brae and Cambodia’s Angkor.
The involvement of citizen scientists has been crucial to not only making this research happen but to the discovery of the curious star in the first place. People participating in the Planet Hunters initiative were responsible for flagging up the unusual light curve of the star.
“If it wasn’t for people with an unbiased look on our universe, this unusual star would have been overlooked,” Boyajian added.
"I am so appreciative of all of the people who have contributed to this in the past year – the citizen scientists and professional astronomers. It’s quite humbling to have all of these people contributing in various ways to help figure it out.”