In 1927, Hermann Zanstra showed that for a star in an optically thick nebula, this quantity can be estimated from the flux of Balmer lines from the nebula. The ratio of this quantity to the 3/2 ["three halves"] power and the square root of density is proportional to the Jeans Mass. In the Mestel theory, the rate of change of this quantity in white dwarfs is proportional to the negative 7/2 [“seven halves”] power of this quantity. According to the Schwarzschild condition, when the radial (*) gradient of this property exceeds its adiabatic value, stars will undergo convection. This quantity to the fourth power is proportional to luminosity in the Stefan-Boltzmann law. According to Wien’s law, stellar color is directly related to this quantity, meaning blue stars have higher values of it. For 10 points, name this quantity which, at the sun’s surface, is 5,770 Kelvin. ■END■ (10[1])