Peruvian astronomers find evidence that a rocky planet was “swallowed” by a star

An international team of astronomers, led by a Peruvian scientist, has detected signs that a rocky planet was absorbed by a star in the HIP 71726-37 binary system, according to a study accepted for publication in the US Astronomical Journal. It is as if the Sun has absorbed the Earth.

Binary systems are made up of two stars that orbit each other. In this case, the stars that make up the HIP 71726-37, HIP 71726 and HIP 71737 system are separated. These were born from the same cloud of molecules and at the same time, so. They are located at a distance of 11 million astronomical units (distance between the Earth and the Sun) from us.

“The difference in chemical composition between the components of the binary should be zero. But this is not observed in HIP 71726-37, since the difference is 0.1 dex. This means that ”, explains the Peruvian astronomer and main author Jhon Yana Galarza, from the Department of Astronomy of the University of Sao Paulo (USP), in Brazil.

In a binary system, the differences in chemical composition do not necessarily indicate that there was an event such as the absorption of a planet, but the difference in the concentration of lithium (Li) does make the study authors think that at some point the star HIP 71726 “Swallowed” a rocky body.

“If one of the stars has much more lithium than the other, This is shown in HIP 71726. This star is richer than its companion HIP 71737, not only in iron but also in lithium, plus or minus 1.3 dex. This means that HIP 71726 is 10 times richer in lithium “, details Yana Galarza, a graduate of the University of San Marcos.

Although more studies are necessary to confirm that this astronomical event happened, the scientist considers that “[este trabajo] is an important indication that and that in some cases they can be swallowed by their stars ”.

To assume that a planet was swallowed by the star of a binary system it is necessary to take into account two elements: the binary system must be chemically inhomogeneous (different in composition) and, on the other hand, the star with the most metals must also be the one richest in lithium. From this, simulations of the astronomical event are carried out.

, but some previous studies have shown that these phenomena are not uncommon. In a recent work published in Nature, a team of researchers, including the Peruvian astronomer Jorge Meléndez, analyzed 107 stars and determined that 25% could have “swallowed” their planet.

The present study, which is hosted in the Arxiv prepublication repository, also includes astronomers Ricardo López (Mexico), from the University of Texas; Jorge Meléndez (Peru), professor at USP; and Diego Lorenzo (Brazil), who is doing a post-doctorate at USP.

Yana and Meléndez, in addition, are authors of the research that accounted for the recent discovery of a group of 129 stars similar to the Sun, which (Sol, in Quechua), one of the main Inca deities.

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