A TEAM OF researchers are one step closer to solving the mystery behind the “most mysterious star in the universe”.
Tabby’s Star, named after astronomer Tabetha Boyajian, is about 50% bigger and 1,000 degrees hotter than the sun, and about 1,000 light years away.
However, it has been inexplicably dimming and brightening sporadically like no other.
The mystery of Tabby’s Star has been found so compelling that more than 1,700 people donated over $100,000 (around €83,160) through a campaign in support of dedicated ground-based telescope time to observe and gather more data on the star.
“We were hoping that once we finally caught a dip happening in real time we could see if the dips were the same depth at all wavelengths. If they were nearly the same, this would suggest that the cause was something opaque, like an orbiting disk, planet, star, or even large structures in space,” co-author of the research Jason Wright said.
Instead, the team found that the star got much dimmer at some wavelengths than others.
The researchers established that dust is most likely the reason why the star’s light appears to dim and brighten.
“The new data shows that different colours 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,” Boyajian said.
The scientists came to this understanding after they closely observed the star through the Las Cumbres Observatory, California from March 2016 to December 2017.
Beginning in May 2017, there were four distinct episodes when the star’s light dipped.
Supporters from the crowdfunding campaign nominated and voted to name these episodes. The first two dips were named Elsie and Celeste. The last two were named after ancient lost cities – Scotland’s Skara Brae and Cambodia’s Angkor.
The authors of the research explained that in many ways, what is happening with the star is like these lost cities.
“They’re ancient. We are watching things that happened more than 1,000 years ago,” the authors wrote.
“They’re almost certainly caused by something ordinary, at least on a cosmic scale. And yet that makes them more interesting, not less. But most of all, they’re mysterious,” they said.
New era of astronomy
The method in which the star is being studied – by gathering and analysing a flood of data from a single target – signals a new era of astronomy.
Citizen scientists sifting through massive amounts of data from the Nasa Kepler mission were the ones to detect the star’s unusual behaviour in the first place.
The main objective of the Kepler mission was to find planets and hence blocking out a tiny bit of starlight. The online citizen science group Planet Hunters was established so that volunteers could help to classify light curves from the Kepler mission and to search for planets.
“If it wasn’t for people with an unbiased look at our universe, this unusual star would have been overlooked,” Boyajian said.
“Again, without the public support for this dedicated observing run, we would not have this large amount of data.”
Now, the researchers said there are more answers to be found.
“This latest research rules out alien megastructures, but it raises the plausibility of other phenomena being behind the dimming,” Wright said.
“There are other models involving circumstellar material – like exocomets, which were Boyajian’s team’s original hypothesis – which seems to be consistent with the data we have.”
Boyajian expressed her excitement at the new findings.
It’s exciting. I am so appreciative of all 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 this out.”
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