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Astronomers offer new theory of planet evolution

Astronomers involved in a recent study have formulated a theory about how “gas giant” planets are created.

Gas giants, such as Jupiter and Saturn in the solar system, are uninhabitable and are so named because they are made primarily of gases, and not solid materials like on Earth.

Astronomers involved in the study utilized the power of the most sophisticated land telescope in existence in order to hypothesize that gas giants are formed by collecting gas and dust that circle new stars. Previous research has revealed that newborn stars are surrounded by this gas and dust from birth and that it stays with the star for millions of years.

“Astronomers have been predicting that these streams must exist, but this is the first time we’ve been able to see them directly,” said University of Chile astronomer Simon Casassus, who led the study. “The planets grow by capturing some of the gas from the outer disc, but they are really messy eaters. The rest of it overshoots and feeds into the inner disc around the star.”

Researchers reached their conclusions after observing a young star, which is referred to HD 142527, over 450 light years from Earth and reported them in the journal Nature. While studying HD 142527, the astronomers noticed a chunk of missing debris surrounding the new star. They say brand new gas giants may be stealing from HD 142527’s gas and dust ring.

The research team now believes that as the gas giants orbit the new star, they steal the gas and dust in the debris ring surrounding the star. In addition, the study revealed that these planets may also collect gas that flows from the outer portion of the star’s debris disk to the inner portion in streams.

Another first is the detection of the diffuse gas in the gap. “Astronomers have been looking for this gas for a long time, but so far we only had indirect evidence for it. Now, with ALMA, we can see it directly,” explains Gerrit van der Plas, another team member at Universidad de Chile.

In order to make their observations, Casassus and his team of astronomers used the Atacama Large Millimeter/Submillimeter Array, or ALMA, telescope. The ALMA telescope was developed by the European Southern Observatory and is still under construction in the Atacama Desert in Chile.

The ALMA telescope allows the user to view light at submillimeter wavelengths and is considered the most sophisticated land telescope in existence today. Utilizing the ALMA telescope, Casassus and his team were able to locate gas streaming through the gap in the inner and outer portions of HD 142527’s debris ring.

The gap in the star’s disk is not small, in fact it starts at approximately 10 astronomical units, or AUs — about 10 times the span of the Earth to the sun, and ends at over 140 Aus. According to Sebastian Perez, who also worked on the project, the researchers believe there is a gas giant developing within about 90 AUs of the gap that is causing the gas streams to form.

The study is likely just the first step towards better understanding the evolution of the largest planets of our solar system. According to the astronomers, an additional study will aim to find out more about the suspected planets by studying the gas streams as well as the diffuse gas. The ALMA telescope is still under construction, and has not yet reached its full capabilities, and  when it is complete its vision will be even sharper, and new observations of the streams may allow the team to determine properties of the planets, including their masses.