Studying planet formation around low-mass stars and brown dwarfs through observations of their circumstellar disks

Observations of circumstellar accretion disks around young stars provide fundamental constraints on the process of planet formation. Disks around low-mass stars and brown dwarfs have been studied extensively in recent years, primarily through infrared imaging and spectroscopy with the Spitzer Space Telescope. I review the observations of these disks that are relevant to planet formation, including disk fractions and lifetimes, the presence of inner holes, grain growth and dust settling, and the abundances of organic molecules. In particular, I summarize the dependence of these properties on stellar mass to compare the prospects for planet formation between stars like the Sun, low-mass stars, and brown dwarfs.