The Big Picture
Why study disks, you ask? The disks around young stars are composed of the leftover material from the formation of the star. Presumably they’re also the raw material for the planets that will eventually form around the star. And once planets form, they will inevitably interact with their natal material. Studying the disks gives us insight into how and when in the life of a star planets might form, and can tell us what types of planets/systems are commonly formed (e.g., is our own solar system typical?)
Below are short descriptions of some of the research themes I have pursued recently (with my excellent collaborators and group members, hence the "we"). If you're a student looking for a project to work on, please send me an email or stop by to chat!
The disks around young stars are accretion disks. Not only does this mean that material falls from the disk onto the star, but also that material is constantly being transported from one part of the disk to another, causing the disk to spread and heat and evolve with time. Understanding how material redistributes itself through the disk is important for understanding when, where, and how much material is available for planet formation. We are conducting observational tests of some of the leading theories about how this evolution occurs.
Unlike the primordial disks around very young (<10 Myr-old) stars,
the dusty disks around main sequence stars are tenuous, virtually
gas-free, and should have lifetimes much less than the age of the star.
So why are they still there? The simplest answer is that these disks
are generated by the grinding collisions of planetesimals that have formed
around the star. Debris disks are exciting for a number of reasons,
not least because they present a unique source of information about the
properties of young planets that are otherwise difficult or impossible
to observe. Some of my current research involves using debris disk morphology to measure the mass of any planetary bodies that might be dynamically stirring the dust.
In order for a disk to transition from the protoplanetary to debris disk phase, its primordial gas and dust must somehow be cleared from the system. There is a lot of interest in exactly how this transition takes place, particularly since this is the time in the life of a disk when it is likely to be forming planets. We have investigated this stage of evolution by making careful imaging studies of systems that seem to be at various stages of the clearing process. We have resolved giant dust cavities in young disks, and have modeled gas and dust in two types of systems at older (~10 Myr) ages: those that retain a molecular gas disk despite evolved debris-like dust, and those that have apparently primordial dust properties but greatly reduced molecular gas masses.