Svelato il mistero della stella più curiosa della galassia
Nel 2015 gli astronomi scoprirono una particolare stella nella costellazione del Cigno a circa 1.600 anni luce dalla Terra.
KIC 8462852 subiva anomale variazioni della sua luminosità apparente. La quantità della luce emessa dalla stella e fotografata dal telescopio spaziale Keple diminuiva anche del 22% in alcuni momenti.
Questa particolarità aveva suscitato la nascita di ipotesi extraterrestri; una Sfera di Dyson attorno alla stella poteva infatti spiegare un'anomalia unica nel suo genere.
Tuttavia nuove rilevazioni suggeriscono ipotesi meno fantascientifiche e che non richiedono megastrutture.
La particolarità della stella KIC 8462852 (o Stella di Tabby) sarebbe da ricercarsi esclusivamente in una enorme concentrazione di polveri che ne schermerebbero la luce.
The mysterious flickering around the star in the swan constellation is likely caused by ordinary dust, according to an analysis of new data published Wednesday in The Astrophysical Journal Letters. Astronomers have found that the mystery dimming is much deeper at blue wavelengths than at red wavelengths, which means the object responsible for it is not opaque. The data suggest that the dimming is likely caused by a cloud of very small particles of cosmic dust, which measure less than one micron each, smaller than the size of a human red blood cell.
"If you imagine you have some light source and a planet—which is an opaque object—goes in front of it, it will block blue light just as much as it would the red light," said Tabetha Boyajian, an astronomer at Louisiana State University who led the analysis. "What we're seeing for this star is that the drop in the star's brightness is much greater in the blue than it is in the red."
If the dimming had occurred in all colors equally, megastructures would still be on the table. "The fact that the data came in the other way means that we now have no reason to think alien megastructures have anything to do with the dips of Tabby's Star," wrote Jason Wright, the Pennsylvania State University astronomer who first suggested the alien megastructure theory, in a blog post Wednesday. (Astronomers have nicknamed the star Tabby’s Star, after Boyajian.)
