An Etymological Dictionary of Astronomy and Astrophysics

An evolutionary stage in the formation of low-mass → protostars resulting from a → Class II object between 1 to 10 million years after the initial → gravitational collapse. At this stage → accretion has ceased completely and what remains
from the → circumstellar disk is a → debris disk. The temperature and density of the → pre-main sequence star keep increasing as the object slowly contracts to its final size. Most of the → luminosity derives from protostellar contraction. The → spectral energy distribution (SED) resembles a stellar → blackbody, peaking at optical and infrared wavelengths. Minor → infrared excess is still observed. The SED has a negative → spectral index (α_IR < -1.5). Class III objects are sometimes called → weak-line T Tauri stars.

See also: → class; → three.