In the standard model of stellar structure (I. Nicholson, The sun. Rand McNally, New

Chapter 21, Problem 21.38

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In the standard model of stellar structure (I. Nicholson, The sun. Rand McNally, New York (1982)), the interior of the Sun is thought to consist of 36 per cent H and 64 per cent He by mass, at a density of 158 g cm3. Both atoms are completely ionized. The approximate dimensions of the nuclei can be calculated from the formula rnucleus = 1.4 1015 A1/3 m, where A is the mass number. The size of the free electron, re 1018 m, is negligible compared to the size of the nuclei. (a) Calculate the excluded volume in 1.0 cm3 of the stellar interior and on that basis decide upon the applicability of the perfect gas law to this system. (b) The standard model suggests that the pressure in the stellar interior is 2.5 1011 atm. Calculate the temperature of the Suns interior based on the perfect gas model. The generally accepted standard model value is 16 MK. (c) Would a van der Waals type of equation (with a = 0) give a better value for T?