An unusual star known to experience dramatic dips in brightness has sparked countless theories since its discovery, with many suspecting an ‘alien megastructure’ could be behind the phenomenon.
But now, scientists say the real cause of the dimming seen at Tabby’s Star may be far more mundane.
Data from NASA’s Spitzer and Swift missions, as well as the Belgian AstroLAB IRIS observatory have revealed the star’s ultraviolet light is dimming more than its infrared during these events.
According to the experts, this means something much smaller than the proposed Dyson Sphere must be to blame – most likely uneven clouds of dust orbiting the star.
The team estimates the objects causing the mysterious dimming at Tabby’s Star are no more than a few micrometers wide. These particles must be larger than interstellar dust – instead, it may be circumstellar dust, or the dust that circles a star. The ring of dust is illustrated above
‘This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming,’ said lead author Huan Meng, of the University of Arizona, Tucson.
‘We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period.’
The researchers liken this type of non-uniform dimming to effects seen on Earth every day.
The sun appears to look red at sunset, for example, because the blue and ultraviolet light is scattered by tiny particles, according to NASA.
In the new study published in the Astrophysical Journal, the team estimates the objects causing the mysterious dimming at Tabby’s Star are no more than a few micrometers wide (or, roughly one ten-thousandth of an inch).
These particles must be larger than interstellar dust – instead, it may be circumstellar dust, or the dust that circles a star.
The researchers collected observational data of Tabby’s star from October 2015 to March 2017 from two Nasa telescopes – Swift, which takes X-ray and UV measurements, and Spitzer, which measures objects in infrared.
Speaking to Inverse in September, Huan Meng, lead author of the study, said: ‘We found that from UV, throughout the visible spectrum, to IR, the star is dimming at every wavelength we monitored.’
It has baffled astronomers since it was first discovered in 2015, but now experts believe they may be one step closer to solving the mystery of Tabby’s star (artist’s impression pictured)
This suggests that initial data collected by Nasa’s Kepler telescope was incorrect.
The researchers discovered that the dimming rate of Tabby’s star differed significantly between UV and infrared, suggesting ‘micro-sized dust screens’ are to blame for this irregular dimming.
Dr Meng said: ‘Only microscopic fine-dust screens are able to scatter the starlight in the way characterized by measurements.’
Rather than aliens, the researchers strongly suspect that a microscopic dust ring originating from circumstellar material found in the system is causing the dimming and brightening of Tabby’s star.
Dr Meng said: ‘It cannot be anything from the interstellar medium.’
But while the researchers suspect the dimming is caused by a dust ring, they stress that ‘this is not a firm conclusion.’
Tabby’s Star has baffled astronomers since it was first discovered in 2015.
The star, otherwise known as KIC 8462852, is located 1,400 light years away, and dims at a much faster rate than other stars, which some experts have suggested is a sign of aliens harnessing the energy of a star.
But the new study ‘eliminates the possibility of an alien megastructure.’
Previous studies have claimed the strange dimming could be evidence of a Dyson Sphere – a hypothetical structure which could be used by an advanced alien race to harness the energy of a star (artist’s impression pictured)
The new findings address the long-term dimming seen at Tabby’s Star, but according to NASA, the shorter-term events still remain a larger mystery.
This phenomenon was observed this year in three-day spurts.
And, the more extreme dips, with up to 20 percent drop in brightness, also remain unaccounted for.
The findings also contradict research published at the end of August, which suggested that a ringed Saturn-like planet was to blame for the irregular dimming.
Researchers from the University of Antioquia in Colombia made the claim in a paper published on the Arxiv electronic archive.
WHAT IS A DYSON SPHERE?
A suggested method for harnessing the power of an entire star is known as a Dyson sphere.
First proposed by theoretical physicist Freeman Dyson in 1960, this would be a swarm of satellites that surrounds a star.
They could be an enclosed shell, or spacecraft spread out to gather its energy – known as a Dyson swarm.
If such structures do exist, they would emit huge amounts of noticeable infrared radiation back on Earth.
But as of yet, such a structure has not been detected.
Creating a Dyson ‘bubble’ would be an incredible engineering challenge but it is considered to be far more feasible than surrounding a star in a rigid sphere
Source: All About Space magazine
They argue that if a ringed planet like Saturn was in close orbit of the star with tilted rings, it would seem to dim the light coming from it in an irregular pattern.
The rings would first block the light as the planet passed in front of the star, followed by the planet itself, before the rings again blocked more light.
And because the tilted rings would be at a different angle on each pass, it would appear to be a random occurrence.
But with enough information, a pattern could be established.