Dirty Stars Make Good Solar System Hosts




 "When you observe stars, the ones with more heavy elements have more planets," says co-author Mordecai-Mark Mac Low, Curator of Astrophysics at the American Museum of Natural History. "In other words, what's in the disk reflects what's in the star. This is a common sense result." Observation of distant solar systems shows that exoplanets, or planets that orbit stars other than the Sun, are much more abundant around stars that have a greater abundance of elements heavier than helium, like iron and oxygen. These elements are the ones that can turn into rocks or ice.








Youdin adds that "There's an inherent advantage in being born rich, in terms of solid rocks. But less advantaged systems, like our own Solar System, can still make planets if they work to marshal their resources and hang onto their solids as the gas evaporates away. So the Sun is middle-class, rather than rich." The Sun's abundance of heavy elements suggests its protoplanetary disk (the disk from which the Solar System formed) had close to the critical ratio of pebbles to gas; if the abundance of heavy elements had been slightly less, planetesimals and planets would have been far less likely to form, and we would not be here to study the question.


The results of this paper will be presented on October 8, 2009 at a meeting of the Division of Planetary Sciences of the American Astronomical Society in Puerto Rico. Computer simulations were performed on the Huygens cluster in Amsterdam and the PIA cluster of the Max Planck Institute for Astronomy. Additional funding came from the NASA Origins of the Solar Systems Program and the NSF Cyberenabeled Discovery Initiative.


Media Inquiries: Department of Communications, 212-769-5800