It is one of the greatest astronomical mysteries of the moment.
Since 2011, known as the star Tabby recorded irregular changes in brightness that cannot be explained by the passage of a planet, which is what usually alter the brightness of stars. These disturbances are variables and create different light curves, so a priori could not be caused by the planet passing in front of Tabby.
Because of this, the origin of these disturbances has baffled scientists. So much so that all sorts of hypotheses have circulated about it.
The most famous of them holds that it is an alien structure, an artificial artifact designed to remain suspended in the universe: a sphere of Dyson (in honor of the designer of the hypothesis); which could be harnessing energy from the star to feed an advanced extraterrestrial civilization , thus causing its brightness to diminish.
However, astronomers are inclined to a simpler and less proper explanation of a science fiction film.
The last analysis that has been made regarding the strange behavior of Tabby again refutes the extraterrestrial hypothesis. Scientists at NASA have concluded that probably the strange structure that seems to surround Tabby is simply a cloud of uneven dust that moves around the star.
The study was based on the Spitzer and Swift missions of NASA and the Belgian observatory AstroLAB IRIS.
According to a NASA statement, the explanation is as follows: the researchers found less obscuration in the star’s infrared light than in its ultraviolet light. This effect can only be produced by dust particles, since any larger object would obscure all wavelengths equally.
To better understand, let’s move it to everyday life: if you go to the beach on a sunny day and sit under the umbrella, this reduces the amount of sunlight that hits your eyes at all wavelengths. But if you wait for the sunset, it will look red, because the blue and ultraviolet light is dispersed through small particles of dust.
The new study suggests that objects that cause long-term obscuration of the Tabby star cannot be more than a few microns in diameter.
That is, they are dust.
A hypothesis that ends with the idea of extraterrestrial mega-structure and other more exotic speculations.
The strange behavior of Tabby
NASA’s Kepler Space Telescope has been observing irregular darkening in the star for years, which, as we have seen, cannot be explained by the passage of a planet in front of it. Even Kepler even detected a darkening of up to 20% in a matter of days. The star has shown other slight glimmers of brightness without a clear periodicity and without plausible explanation.
Its origin is, at least, enigmatic.
The fundamental thing is that none of these behaviors is the one expected for stars more massive than the Sun, nor has it ever been observed in any of them.
Another possible explanation
This year, a team of Spanish researchers from the University of Valencia and the Institute of Physics of Cantabria elaborated another possible explanation , something more complex but equally plausible.
Although in principle it was ruled out that these changes of brilliance were produced by the passage of a planet, due to irregular curves of them, the Spanish team determined that the changes would not only produce a massive planet, but also that it would have rings , and would be accompanied, in his step, of two groups of asteroids.
Detailed observation will be needed to test this hypothesis, which can be done in 2023, the next time we pass Tabby, theoretically, and this supposed planetary group.
In either case, the alien hypothesis loses force. However, there is as yet no evidence and therefore no hypothesis can be ruled out.