Instead of solving the mystery, a new study from Carnegie’s Josh Simon and Caltech’s Ben Montet has deepened it.

Let’s cover a bit of background about this unusual star (that is 1,500 light-years away!) before we look at the new analysis.

From our coverage back in January:

The star, KIC8462852, has confused astronomers because the light it gives off keeps changing in fast, drastic ways that do not follow any pattern. Between 2009 and 2013 for example, the star would randomly lose up to 20% of its brightness. Planets etc. revolving around it were ruled out because the dimming would follow a pattern in that case and this didn’t.

Last year, Penn State astronomer Jason Wright announced that it is possible that alien life may exist around the mysterious star.

KIC 8462852 achieved fame in 2015 when a scientific paper suggested that a vast alien megastructure could have been responsible for temporary dips in the luminosity of the star that were recorded by the Kepler Space Telescope first in 2011, and then again in 2013.

The Kepler was looking for tiny dips in the light emitted by the star. These dips are often shadows cast by transiting planets — especially when they repeat periodically — as you’d expect if they were caused by orbiting objects. But because Kepler was looking for these dips in more than 150,000 stars simultaneously, it was hard for the science team to sort out all the data.

So, the Kepler team sought help from the public, as The Atlantic reported last year:

The Kepler Space Telescope collected a great deal of light from all of those stars it watched. So much light that Kepler’s science team couldn’t process it all with algorithms. They needed the human eye, and human cognition, which remains unsurpassed in certain sorts of pattern recognition. Kepler’s astronomers decided to found Planet Hunters, a program that asked “citizen scientists” to examine light patterns emitted by the stars, from the comfort of their own homes.

In 2011, several citizen scientists flagged one particular star as “interesting” and “bizarre.” The star was emitting a light pattern that looked stranger than any of the others Kepler was watching.

Last September, New Scientist asked Tabetha Boyajian of Yale University, who led a team of astronomers investigating the signal, about the citizen scientists’ reports:

It was kind of unbelievable that it was real data. But after checking and double checking for anything that could have gone wrong with the telescope, they decided the signal must be real – and were forced to come up with an explanation. We were scratching our heads. For any idea that came up there was always something that would argue against it.

In October of 2015, Boyajian published a paper titled “Where’s The Flux?” (a joking reference to the slang expression of disbelief “WTF” – a nickname for the star itself is the “WTF star”) describing the star’s mysterious behavior.

Several of the citizen scientists are listed as co-authors. The paper explores a number of scenarios that might explain the pattern: instrument defects, the shrapnel from an asteroid belt pileup, or an impact of planetary scale, like the one that created our moon. While the paper concluded that something must be blocking the star’s light from the outside, exactly what that is has yet to be determined.

Boyajian’s paper only considered natural explanations, but she has said she’s open to exploring unnatural ones.

Wright said of the data:

When [Boyajian] showed me the data, I was fascinated by how crazy it looked. Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.

Now, to the new findings.

Phys.org reports:

Simon and Montet’s findings caused a stir in August, when they were posted on a preprint server while their paper was being reviewed. Now their work is now accepted for publication by The Astrophysical Journal.

The researchers analyzed further Kepler observations of the puzzling star and showed that in addition to its rapid unexplained brightness changes, the star also faded slowly and steadily during the four years it was watched by Kepler.

Speculation to explain KIC 8462852’s dips in brightness has ranged from an unusually large group of comets orbiting the star to an alien megastructure. In general, stars can appear to dim because a solid object like a planet or a cloud of dust and gas passes between it and the observer, eclipsing and effectively dimming its brightness for a time. But the erratic pattern of abrupt fading and re-brightening in KIC 8462852 is unlike that seen for any other star.

Simon and Montet found that, over the first three years of the Kepler mission, KIC 8462852 dimmed by almost 1 percent. Its brightness then dropped by an extraordinary 2 percent over just six months, remaining at about that level for the final six months of the mission. They compared this with more than 500 similar stars an found that none exhibited such a dramatic dimming in just six months, or a total change in brightness of 3 percent.

“The steady brightness change in KIC 8462852 is pretty astounding,” said Montet. “Our highly accurate measurements over four years demonstrate that the star really is getting fainter with time. It is unprecedented for this type of star to slowly fade for years, and we don’t see anything else like it in the Kepler data.”

“This star was already completely unique because of its sporadic dimming episodes. But now we see that it has other features that are just as strange, both slowly dimming for almost three years and then suddenly getting fainter much more rapidly,” Simon added.

The six months of dimming could be explained by the breakup of a planet or comets, but the apparent long-term fading must be something else. And, they still don’t know what caused the dramatic change in brightness that was reported last year.

These new findings will make the already challenging research on the WTF Star even more difficult, astronomers say:

“It’s a big challenge to come up with a good explanation for a star doing three different things that have never been seen before,” Montet said. “But these observations will provide an important clue to solving the mystery of KIC 8462852.”

Last year, astronomers searched for signs of potential laser communications and radio signals coming from KIC 8462852, but found nothing.

Wright and his colleagues plan to begin more research this month, however. They’ve secured time on West Virginia’s huge Green Bank Telescope for this purpose, reports Space.com:

“This is a 1-in-300,000 object,” Wright said. “People have gone looking for more, and it’s the only one. So that also says you’re allowed to invoke one really rare thing, because it is a rare phenomenon.”

In this video, author and futurist John Michael Godier discusses the star.