Astronomers may have to think a little harder to solve the mystery of Boyajian’s star reports Space.com.
In September 2015, Yale University’s Tabetha Boyajian and her colleagues reported that the star KIC 8462852 has dimmed dramatically multiple times over the past seven years, once by an astounding 22 percent.
NASA’s planet-hunting Kepler space telescope spotted these dimming events. But the brightness dips of “Boyajian’s star,” as it has come to be known, were far too significant to be caused by an orbiting planet, so astronomers began thinking of alternative explanations.
Researchers have come up with many possible causes for the dimming, including a swarm of broken-apart comet fragments, variability in the activity of the star itself, a cloud of some sort in the interstellar medium between Kepler and Boyajian’s star, and, most famously, an orbiting “megastructure” built by an alien civilization to collect stellar energy.
Researchers are testing these hypotheses to the extent possible.
The mystery has only deepened since Boyajian and colleagues’ September 2015 paper. Early last year, for example, astronomer Bradley Schaefer of Louisiana State University determined that, in addition to the periodic brightness dips, the star dimmed overall by about 20 percent between 1890 and 1989. This result was bolstered by another 2016 study, which found that Boyajian’s star dimmed by about 3 percent between 2009 and 2013.
Wright has said that the interstellar-cloud explanation seems the most likely of the proffered hypotheses. But he’s not betting on it. “That would have to be some crazy interstellar cloud,” he told Space.com here last week at the annual fall meeting of the American Geophysical Union.
Researchers may have to dig deeper to figure out exactly what’s causing the strange dimming of Boyajian’s star, Wright said.
“I think it’s very likely that we haven’t heard the right answer yet — that I haven’t heard the right answer yet, anyway,” he said.