Galactic disk
= Galactic disk
= Galactic disc
{synonym}
A <galactic disk> is a flattened stellar or gaseous component of a <galaxy>, commonly supported mainly by ordered rotation. Its radial mass profile determines its <galaxy rotation curve>; thickness, truncation and external forces also matter. A <galactic disk> need not be an <exponential galactic disk>, and its neutral-gas absorption radius need not equal a stellar scale length.