subgiant(redirected from Sub-giant)
subgiant(sub-jÿ -ănt) A giant star of smaller size and lower luminosity than normal giants of the same spectral type, Alpha Crucis being an example. Subgiants form luminosity class IV, lying between the main-sequence stars and the giants on the Hertzsprung–Russell diagram.
a member of a group of cool stars located between the giants and the main sequence in the Hertzsprung-Russell diagram. By comparison to main sequence stars of the same luminosity, subgiants are larger and have lower surface temperatures. Most known examples of subgiants are found in eclipsing binary systems of the Algol type. Subgiants apparently represent a late stage in the development of binary stars.