Massimo Marengo’s work in stellar astrophysics keeps returning to the mysterious dimming of Tabby’s star some 1,000 light years from Earth. This particular middle-aged star — KIC 8462852, also known as Tabby’s Star or Bayesian’s Star, after Tabatha Bayesian, a Louisiana State University astronomer and lead author of a 2016 paper introducing the star — is an interesting case.
Tiny dips in a star’s brightness can indicate a planet is passing in front of the star. This star was dimming by up to 20 percent. It was also dimming irregularly, sometimes for days and months at a time. And smaller, longer-term dimming continues today.
The star can potentially tell us a lot about the kind of processes that happen in the planetary systems of regular stars. But this is very rare — it’s the only star we’ve found that shows these phenomena.
The paper’s findings are based on space observations from NASA’s Spitzer and Swift missions, plus ground observations from amateur astronomers at Belgium’s Astor LAB IRIS public observatory. All the observations were from October 2015 through December 2016, and from ultraviolet to mid-infrared wavelengths, including visible light.
That he combined NASA observations with the data from Belgium. Tuba developed software to help with the analysis.
It turns out there was less dimming of the star’s infrared light than its ultraviolet and visible light.
Much more likely is circumstellar dust — small particles orbiting the star — blocked some of the shorter ultraviolet light but allowed larger wavelengths of infrared light to jump though, he said.
Marengo said the data seems to indicate the dust particles are too large to be the kind usually found in interstellar dust clouds between the star and Earth.
A 2015 study by Marengo and two former Iowa State graduate students, published by The Astrophysical Journal Letters, looked at deep, short-terms dips in the star’s brightness.
Even with all the recent attention, Marengo said there’s still more to learn from this star.