A disk component of a → spiral galaxy
containing → stars, → gas,
and → dust
which are confined to the galaxy’s → plane of rotation.
In contrast to
→ thick disks, thin disks
contain the bulk of the → baryonic matter in spiral
galaxies. For example, on the order of 60-90% of the baryonic matter in the
→ Milky Way is located in the thin disk. The scale height of the
thin disk in the Milky Way is about 400 → light-years,
whereas its scale length is about 10,000 light-years. Moreover, the outer regions of
thin disks appear to be bent by the → warp phenomenon.
The thin disks of spiral galaxies are active sites of
→ star formation, especially in
the spiral arms. For this reason, stars in the thin disk tend to be
relatively young. Thin disk stars also tend to be
→ metal-rich compared with thick disk and
→ halo stars,
and typically have a → metallicity similar to that of the Sun.
See also: → thin; → disk;
