Sun-like Stars that Gobble Earth-like Planets Analyzed for Chemical Signature (VIDEO)

Sun-like stars don't just provide warmth to their planets. Scientists have found that these stars are "earth-eaters" and that during their development they ingest large amounts of the rocky material that form terrestrial planets. Now, scientists are looking a little bit closer at these sun-like stars, learning a bit more about their chemical composition and what effects this might have on their nearby planets.

Stars consist of more than 98 percent hydrogen and helium. All of the other elements make up less than 2 percent of their mass. These other elements, which are heavier than the two main gases, are metals; astronomers have coined the term "metallicity" to refer to the ratio of the relative abundance of iron to hydrogen in the star's chemical makeup. For years, scientists have attempted to link star metallicity with the likelihood of planet formation.

In order to find out whether metallicity could indeed impact planet formation, the researchers looked at the abundance of 15 specific elements relative to that of the sun. Then, they examined the planet-hosting binary pair of stars called HD 20781 and HD 20782.

"Trey has shown that we can actually model the chemical signature of a star in detail, element by element, and determine how that signature is changed by the ingestion of Earth-like planets," said Keivan Stassun, one of the researchers, in a news release. "After obtaining a high-resolution spectrum for a given star, we can actually detect that signature in detail, element by element."

Both of the stars that the researchers studied are G-class dwarf stars, similar to the sun. One star is orbited by two Neptune-sized planets while the other possesses a single Jupiter-sized planet. After analyzing the spectrum of the two stars, the researchers found that the higher the melting temperature of an element, the higher its abundance. In addition, they found that the two stars had different chemical compositions; the star with the Jupiter-sized planet appears to have swallowed an extra ten Earth masses in comparison to our sun while the one with the Neptune-sized planets scarfed down an additional 20. This in particular serves as a compelling signature of the ingestion of Earth-like rocky material. These findings actually support that a star's chemical composition and the nature of its planetary system are linked.

"Imagine that the star originally formed rocky planets like Earth. Furthermore, imagine that is also formed gas giant planets like Jupiter," said Trey Mack, one of the researchers, in a news release. "The rocky planets form in the region close to the star where it is hot and the gas giants form in the outer part of the planetary system where it is cold. However, once the gas giants are fully formed, they begin to migrate inward and, as they do, their gravity begins to pull and tug on the inner rocky planets. With the right amount of pulling and tugging, a gas giant can easily force a rocky planet to plunge into the star. If enough rocky planets fall into the star, they will stamp it with a particular chemical signature that we can detect."

The findings are published in The Astrophysical Journal.