Complex sentence: However, material continues to enter the gap on the timescale of the larger accretion disk, moving the planet and gap inward on the accretion timescale of the disk.
Split into simpler sentences: However, material continues to enter the gap on the timescale of the larger accretion disk, moving the planet and gap inward. The timescale of this process corresponds approximately to the accretion timescale of the disk.