Among solar-type main sequence stars with FGK spectral types, exoplanets and debris disks are fairly common. Exoplanets and debris disks grow out of massive disks of gas and dust that surround every newborn solar-type star. With Joan Najita and Ben Bromley, my research focuses on the transformation of a dusty disk into a planetary system and debris disk.
The schematic to the left illustrates the basic problem. Young stars with ages of a few Myr or less have two broad classes of disks as shown in the two panels in the left of the graphic. All have a compact disk with a radius of 20-40 au. In roughly 25%, bright rings of gas and dust lie outside the compact disk; the rest may have undetected rings. Stars with ages of 100~Myr and older (illustrated in the two right panels of the graphic) may have a set of debris rings or a set of planets or both. We collect observational data and perform numerical calculations to see which paths are most commonly followed. So far, it seems that rings evolve along all four paths from the two left graphics to the two right graphics. The two horizontal paths, from bright rings to debris disks and from compact disks to planetary systems seem more common than the two diagonal paths.
Our recent projects include:
- We have built a comprehensive compilation of data on stars observed by the Spitzer and Herschel satellites to identify cold debris disks. We plan to use these data to learn how disks and rings of gas and dust surrounding young stars become planetary systems.
- We have used observations of young stars to compare the masses of their protoplanetary disks to the masses of planets around much older stars. This analysis indicates that planet formation begins in the first few hundred thousand years in the life of a young star. Recent analyses show evidence for planet formation in the disks of the youngest known stars with ages of less than 500,000 yr.