(temperature of an equivalent black body in terms of total radiation)
The effective temperature (Teff, Teff,
or what is often meant by black-body temperature, TBB)
of an astronomical body such as a star or planet
is the calculated temperature of a black body of the same size
with the same bolometric luminosity, i.e., the same
total radiationenergy output rate.
It can be considered an estimate of the body's
surface temperature, imperfect for being determined
at a distance and because a star's surface itself is
ambiguous: the radiation reaches us from more than one depth
into the star, and these layers have differing temperatures.
The various temperature determination methods in use
differ but do have some general agreement.
Among other measures are brightness temperatures
(based on a single wavelength or narrow passband) and
color temperatures (based on a color index).