Answer: 5800 K
Step-by-step explanation:
The Sun is a star found in the center of the solar system amd almost a perfect sphere of plasma. It constitutes the largest source of electromagnetic radiation in this planetary system and it also generates a magnetic field through a dynamo process. About three-quarters of the Sun's mass consists of hydrogen while the rest is mainly helium, with much smaller amounts of other elements such as oxygen, carbon, neon and iron.
Such as any other star, the Sun has a spherical shape, and because of its slow rotation movement, it also has a slight polar flattening. All the matter that constitutes it is attracted towards the center by its own gravitational force. However, the plasma that forms the Sun is in balance, since the increasing pressure in the solar interior compensates the gravitational attraction, which generates a hydrostatic balance. These enormous pressures are produced due to the density of the material in its nucleus and to the enormous temperatures that occur in it thanks to the thermonuclear reactions that take place there. There is, besides this thermal contribution, one of photonic origin which is the radiation pressure caused by the enormous flow of photons emitted in the center of the Sun.
The quantum mechanics allows to calculate the spectral lines of the atoms and molecules that compose the solar atmosphere at any temperature, however the calculation is not easy. For this reason there are several heavy atomic elements with spectral lines that have transition probabilities that are still uncertain.
However, despite being complicated, scientists have determined that the surface temperature of the Sun is around 5800 K.