Solar System's Youth Gives Clues to Habitable Planet Hunt

Our solar system formed about 4.6 billion years ago--relatively recently in the grand scheme of the universe. The comets and meteorites left over from that time contain clues to our solar system's earliest days; unfortunately, some of the findings don't seem to match up. Now, scientists have developed a new set of theoretical models that could explain why some of these findings just don't seem to add up.

There are several ways to examine our solar system's formative period. One is to study samples of small crystalline particles that were formed at high temperatures but now exist in icy comets. Another method is to analyze the traces of isotopes found in primitive meteorites. Over time, these isotopes decay and turn into different elements; the initial abundances of these isotopes, in turn, tell scientists where they might have come from and show how they might have traveled around the early solar system.

Although scientists have been employing these methods for years, though, there are some discrepancies in the research. The general theory is that our solar system formed when a disk of rotating gas around our sun transferred material to the star. Yet analysis of particles and isotopes from comets and meteorites present a mixed picture of solar system formation. It's not just a matter of mass transfer. Researchers found that the heat-formed crystalline grains in comets imply significant mixing and outward movement of matter from close to the star to the outer edges of the solar system. In addition, some isotopes, such as aluminum, support this view. Other isotopes, though, seem to pain a different picture.

In order to find out exactly what was happening, the researchers created new models. These models demonstrated how a phase of marginal gravitational instability in the gas disk surrounding a proto-sun, leading to an outburst phase, could explain the contrary findings. In addition, the model also shows that the ratio of aluminum isotopes can be explained by the parent isotope having been injected in a one-time event into the planet-forming disk by a shock wave from an exploding star and then travelling both inward and outward in the disk.

"These results not only teach us about the formation of our own solar system, but also could aid us in the search for other stars orbited by habitable planets," said Alan Boss, one of the researchers, in a news release. "Understanding the mixing and transport processes that occur around Sun-like stars could give us clues about which of their surrounding planets might have conditions similar to our own."

The findings are published in The Astrophysical Journal.