How do planets form?

We live at a time in human history when we know that our galaxy is teeming with rocky planets like ours. Whether or not such planets are habitable is linked to the building blocks and raw materials that were present in their planetary nurseries. As it was forming 4.5 billion years ago, our solar system was embedded within such a nursery, or protoplanetary disk, with the right conditions to create a habitable rocky planet with a gaseous atmosphere. Since we cannot go back in time to study these conditions in our solar system, I turn to protoplanetary disks in our galaxy to understand how planets form.

Credit: NAOJ

What are the footprints of forming planets?

As planets form, they create telltale footprints in the shape of ring-like gaps in the protoplanetary disk. This is because planets will accumulate and clear out the material around themselves as they form.  I search for gaps in protoplanetary disks to catch planet formation in action.  I work with models and multiwavelength data to detect and measure the sizes of gaps in protoplanetary disks to link these measured observational properties to theoretical models.


Credit: NASA/JPL-Caltech/T. Pyle (SSC)

What is the timescale for planet formation?

Since significant gas must be present in the protoplanetary disk for gas giant planets to form, the lifetime of the protoplanetary disk places an upper limit on the timescale for giant planet formation. The longevity of gas in the disk is dictated by the rate at which gas is eroded by photoevaporative winds created by high-energy ionizing radiation from the central star.  I work to improve our understanding of disk photoevaporation by measuring infrared emission lines that have been proposed to be diagnostic of this high-energy radiation.


Credit: NASA/JPL-Caltech/R. Hurt (IPAC)

How do young protoplanetary systems change over time?

Studying the interaction between the protoplanetary disk and its host star is crucial since the star is the dominant heating source of the disk and, therefore, impacts the disk structure and composition. While we know that high-energy radiation fields of young stars are highly variable, we do not understand how or if the variability results in disk structural and compositional changes.  I work with multiwavelength, multi-epoch data to trace the connection between changes in the high-energy emission of young stars and the surrounding disk.