~Twin stars but very different ~

~ Kronos the world-eater & Krios a comoving pair of sun-type stars ~

In a very close galaxy. Two twin stars in the constellation of Cassiopeia.Apparently the same but one of them hides a dark secret..

After this little film introduction ..

This artist’s illustration shows a planet-eating star. Image credit: NASA / CXC / M.Weiss.

The lead author of the study is Sameyong Oh, from Princeton University. But universities as prestigious as Columbia, Yale and the famous Max Planck Institute have collaborated.

Not too far…

Located 350 light years from Earth in the Constellation of Cassiopeia, what in astronomical terms means very close. A team of astronomers have just discovered a binary star system, one of which has turned out to be an authentic "planetary eater".

They discover the existence of Kronos, the star that eats worlds, the scientific study sustains that at least 15 Earth masses.

Image Source STScI Digitized Sky Survey

HD 240430 named Kronos

HD 240429 named Krios

Dubbed Kronos, the Titan of Greek mythology that devoured its children, the analysis of the chemical composition of the star reveals, in fact, that for now it has "swallowed" a quantity of rock mass equivalent to 15 Earths.

We have to take into account that our inner solar system in which we find ourselves adds a total of just over two Earth masses. Which leads us to say that Kronos should have swallowed at least seven times the mass of our inner solar system.

The research, of course, did not start with the intention of "hunting" a world-eater. The scientists were reviewing a catalog with star data from the Gaia mission of the European Space Agency (ESA), looking for star pairs. that had similar speeds and trajectories. This type of "couples" are usually formed by two twin stars, which are born one very close to the other and from the same ingredients.

John Brewer, who was conducting an analysis of the chemical composition of those stars. And by comparing the data the researchers identified Kronos and Krios, who seemed to form a conventional binary system.

But..

But the combined data of both researchers made no sense, at least at the beginning. In fact, the stars of a binary system are usually virtually identical, while Kronos and Krios, had a very different "chemical makeup", including the largest difference in metal content observed in any other binary system to date.

Chemical discrepancy…

Possible explanations included that one of the two stars was older than the other; or that both were formed from different gas clouds; or that the materials of the original gas cloud were not uniformly mixed. But in the end, they were all dismissed as unlikely.

Hypothesis..

That was how the hypothesis that one of the two stars was a devourer of worlds was opened. And this despite the fact that there is no direct evidence that there are planets orbiting the binary system.
The differences in the compositions of Kronos and Krios are more pronounced in elements such as iron, silicon, magnesium and lithium, metals that make up the bulk of rocky planets like Earth. And since the researchers found that these elements are concentrated in the outer layers of Kronos, instead of mixing in the entire mass of the star, they concluded that, in all likelihood, the star had devoured a number of planets from the stars. first billion years, or more, from the moment of his formation. In this way, the added materials could alter the composition of the outer layers of Kronos and make them different from their twin Krios.

Previous studies had already provided similar evidence of other types of stars devouring planets, but a case as extreme as this one had never been observed.

The next Gaia data could reveal planets with very elliptical orbits around Kronos. His twin Krios, on the other hand, stayed far enough away from other stars and has not suffered similar effects in his eventual planetary system.