Observations of the protoplanetary disks that surround young stars provide crucial information about the initial conditions for planet formation. In a recent study, a team of scientists has proposed a novel new approach for determining disk properties from observations.
Limitations to Direct Measurement
Artist’s impression of a protoplanetary disk surrounding a young star. [ESO/L. Calçada]The surface density of protoplanetary disks (i.e., how much mass is there and where is it concentrated?) can’t be measured directly, since most of the disk mass is in molecular hydrogen gas, which doesn’t readily emit.
Instead, disk surface densities are inferred by measuring other components of the disk, like dust or molecules like CO or HD, and then making assumptions about the molecular abundances or the dust-to-gas ratio in the disk. Disk surface density estimates are therefore heavily dependent upon the assumptions that went into them.
Now, a team of scientists led by Diana Powell (University of California Santa Cruz) has proposed a new technique in which observations of a disk in different wavelengths can be used to determine its surface density profile without the need for such assumptions.
Schematic showing disk dust lines for three different particle sizes, s1 > s2 > s3. Particles ...