gerder-ye nâzok, disk-e ~
Fr.: disque mince
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.