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A team of astronomers who had been creating a survey of stars at the Max-Planck Institute for Astronomy in Heidlberg, Germany have detected a planetary system – 375 light-years away in the constellation Cetus – that is nearly as old as the universe.
The star in the system, designated HIP 11952, is estimated to be 12.8 billion years old, having formed just a billion years after the Big Bang. Our system, by comparison, is only 4.6 billion years old. Two gas giant planets, HIP 11952b and HIP 11952c, each the size of Jupiter, orbit HIP 11952 and have an orbital period of seven days and nine and a half months, respectively.
The age of this system is certainly stunning, but the composition of the HIP 11952 and its planets are what baffles astronomers: they lack the presence of heavy elements (carbon, oxygen, and iron, for example), contradicting a major aspect of the Accretion theory.
Basically, the Accretion theory describes how solar systems are born and develop, but it also states that planets need a high concentration of heavy elements to form. Many planets that astronomers have studied before the discovery of the HIP 11952 system have all been made of many heavy elements. Even the gas giants in our own solar system contain them – mostly metals in their cores, which need these elements in order to form.
However, shortly after the Big Bang, the lighter elements (hydrogen and helium) dominated the universe. Stars were just beginning to form. Only when these first stars went nova did heavy elements exist, but this must have occurred billions of years following the Big Bang, considering the average lifespan of stars.
Despite the contradiction brought forth by the HIP 11952 system, the Accretion theory is still backed-up by evidence of other planets – largely detected by the NASA spacecraft Kepler – that are composed of heavier elements. These planets and their parent stars, however, are young in comparison with the universe’s age.
Nonetheless, the fact that HIP 11952b, and HIP 11952c exist proves that planets are able to form without the presence of heavy elements and, therefore, have astronomers considering new possibilities of how planets come into being. To solve the Accretion theory issue, they would need to further find and study older and metal-poor planets.
“We would like to discover and study more planetary systems of this kind,” Anna Pasquali tells Huffington Post. Pasquali is a co-author of the team’s paper and is from the Center for Astronomy at Heidelberg University (ZAH). “That would allow us to refine our theories of planet formation. The discovery of the planets of HIP 11952 shows that planets have been forming throughout the life of our Universe.”
According to their paper, the team accounts for the lack of heavy elements and HIP 11952’s long age by surmising that HIP 11952 is a dwarf star, a type of star that has low metallicity and a long lifespan.