text: For an object at high redshift, a K-correction must be applied to this quantity to convert it to an equivalent measurement in the rest frame of the object.
full_question: For an object at high redshift, a K-correction must be applied to this quantity to convert it to an equivalent measurement in the rest frame of the object. Dividing a body's kinetic energy by this quantity gives its Kelvin-Helmholtz time scale. An empirical law sets this quantity for a main-sequence star proportional to its mass to the 3.5th power. The fifth root of one hundred is known as Pogson's ratio because N. R. Pogson developed the Hipparchus scale for measuring a logarithmic variety of this quantity, which is called "apparent" if measured from the perspective from the earth. For 10 points, name this quantity which is proportional to the fourth power of temperature in the Stefan-Boltzmann equation, the energy per unit time emitted by a stellar object.
first_sentence: For an object at high redshift, a K-correction must be applied to this quantity to convert it to an equivalent measurement in the rest frame of the object.
raw_answer: luminosity [or apparent magnitude; or absolute magnitude; prompt on "brightness"]