Large Planets, Big Questions

The beginning and the end of star formation was never of major concern to astronomers. However, what happens in between was a mystery to be solved and today astronomers have developed a theory which might help explain this phenomenon.

The new theory is computer modeled and it shows how rocky boulders around infant stars team up to form planets without actually falling into stars. Mordecai-Marc Mac Low, who is an astrophysicist at the American Museum of Natural History in New York City, said that the mid-way of planet creation has been a stumbling block for approximately thirty years. The biggest reason, he explains, is that boulders tend to actually fall into the star. For this not to happen, a new mechanism needed to be developed to prevent them from dragging into a star. And the solution is very simple: put a bunch of boulders together, they join and fight a cosmic headwind that would otherwise doom them. The dust around the stars originates in an accretion disk, which is basically a collection of dust and gas that circles around a star. Now, what happens over time is that this dust and gas start to form boulders by bunching together. Eventually, they meet wind resistance from the disk’s mist of gas. This wind tends to be deadly – it drags the boulders right into the star. However, the new computer modeled theory showed that boulders can actually crunch together and form new planets. "Turbulence in the disk concentrates boulders in regions of higher pressure," Mac Low said, noting that such a disturbance is enough to enable the boulders to fight the dooming headwind. "If the gas is sped up, the boulders don't see a headwind. By getting the gas going with them they conserve energy and stay in orbit. The end of the story is that enough boulders gather together, gravity takes over and they collapse into planet-like bodies.” Mac Low’s research will be published in the upcoming issue of the journal Nature. Even though the solution to the mind tickling problem seems too easy, Mac Low notes that there are many questions that remain. He notes that the whole process of planet creation cannot be deemed to be an open and shut case. Also, scientists are unaware how exactly these boulders collapse into a planet because there are thousands upon thousands of them. However, he believes the theory is reliable and will help explain how large objects form. In the future, Mac Low and his team plan to address the mystery behind collapsing boulders into planetesimals or protoplanetary chunks of rock.