The star, named HIP68468, is similar to our Sun in terms of size, mass and luminosity and calculations show the age of this star is similar to that of the Sun. Stars similar to the Sun are known as “solar twins” and solar twins are useful to study to provide insights into what is likely to happen in our solar system.
In 1995, the first planet known to orbit a star other than the Sun was discovered. In the 21 years since then, 2,000 exoplanets have been found. Observations of exoplanets orbiting solar twins are useful to determine what might happen to Earth and other planets in the solar system. The search for more exoplanets is continuing.
HIP68468 has been studied by Jorge Melendez of Brazil’s Sao Paulo University. Using the telescope at Chile’s La Silla Observatory, Melendez discovered one of the planets orbiting HIP68468 was missing.
Researchers discovered HIP68468 has four times the amount of lithium that should be found in a star its age. A large amount of heat-resistant metals were also found in the star, leading scientists to conclude HIP68468 consumed planets that fell into it. The metals found in the star are those usually found on rocky planets.
Excess lithium is not unique to HIP68468. Of the 60 solar twins that have so far been discovered, 15 percent were found to have more lithium than would normally be expected. More systems will have to be studied to determine how common it is for stars to eventually swallow planets that orbit them.
The big question is will the Earth eventually be “eaten” by the Sun? According to scientists, there is no need to panic at least for now. Jacob Bean, of the University of Chicago, said the research shows many planetary systems, including the solar system, have violent histories. Observing HIP68468 provides information on how planetary systems evolve over time.
Debra Fischer, a professor of astronomy at Yale University, did not take part in the study but has observed computer simulations. According to Fischer, these simulations show billions of years from now gravitational tugs will result in Mercury falling into the Sun. Venus and Earth could follow. Although researchers have not actually observed a star eating a planet, there is no doubt it occurred. Fischer likened the situation to a cat and a canary. If a cat is seen sitting next to a canary’s cage with yellow feathers in its mouth, it is pretty well certain the cat ate the canary.
The research has been published in the journal Astronomy & Astrophysics.
