The temperature of the free electrons in a plasma, determined from their mean kinetic energy; also known as kinetic temperature. Inside stars, this measure of temperature is likely to give close agreement with other methods, but in rarefied gases found in nebulae and the outer atmospheres of stars it is often quite different. For example, the electron temperature of the solar corona ranges from 500 000 to 2 million K, although its effective temperature is only about 50–100 K.