Fig3_6 Internal compression of the Sun

Fig3_6 Internal compression of the Sun

Fig. 3.6 . The variation of pressure, luminosity, temperature and mass density with fractional radial distance from the Sun's center (left) to its visible disk (right). At the Sun's center, the temperature is 15.6 million K and the mass density is 151,300 kg m-3; the central pressure is 2.33 x 1016 Pa or 233 billion times that of the Earth's atmosphere at sea level (one bar equivalent to 100,000 Pa). Nuclear reactions occur only in the central core, out to about 25 percent of the Sunís radius. The energy produced in the core is transported by radiation out to 71 percent of the starís radius, where the temperature has dropped to about 2 million K and the density has fallen to about 200 kg m-3. The energy is then transported by convection out to the Sunís visible disk, known as the photosphere, where the temperature is 5780 K, and the pressure and density have dropped off the scales of the graph.

Copyright 2010, Professor Kenneth R. Lang, Tufts University