nai

Project Progress

We have run the most realistic simulations of the final stages in the formation of Earth-like planets to date (Raymond), including 10 times as many particles as previous simulations. We have also applied models of terrestrial planet growth to several new astrophysical environments:

1. Around low-mass stars (Raymond, Scalo, Meadows). Assuming that planets below a certain mass cannot sustain life, we have shown that low-mass stars may have a lower probability of harboring habitable planets.
2. In systems with close-in giant planets (Mandell, Raymond). We have shown that terrestrial planets in the habitable zone can co-exist with close-in giant planets. These habitable zone planets are likely to be covered by global oceans.
3. In the known sample of giant planets around other stars (Raymond, Mandell). We have developed rough limits on which giant planet orbits allow habitable planets to form.
4. In binary star systems (Raymond). We have shown that habitable planets can form in an astronomically relevant subset of binary star systems.

We have also examined the formation of planetesimals, the building blocks of terrestrial planets (Scalo). New results from 3D hydrodynamical simulations indicate that protoplanetary disks may be seeded with ~100 meter-sized bodies that formed via gravitational collapse of turbulence-concentrated grain clusters within the parent molecular cloud. The presence of these building-sized objects may avert a major problem for the growth of larger bodies, because in traditional models for particle evolution in disks, interactions with the gas cause m-sized bodies to fall into the Sun on very short timescales.

Finally, we have studied the delivery of organic molecules, particularly carbon, to the Earth and habitable planets (Kress). We have found that protoplanetary disks may contain “sootlines”, inside which carbon is unable to condense due to too-high temperatures (analogous to the “snowline” for water). Habitable planets must acquire their carbon from beyond this sootline.

{{ 1 }}

{{ 2 }}