▁from ▁the ▁Christ ensen - D als ga ard ▁review ▁of ▁hel io se ism ology , ▁Chapter ▁IV . ▁ ▁Equ ations ▁of ▁state ▁The ▁numerical ▁solution ▁of ▁the ▁differential ▁equations ▁of ▁stell ar ▁structure ▁requires ▁equations ▁of ▁state ▁for ▁the ▁pressure , ▁opacity ▁and ▁energy ▁generation ▁rate , ▁as ▁described ▁in ▁stell ar ▁structure , ▁which ▁relate ▁these ▁variables ▁to ▁the ▁density , ▁temperature ▁and ▁composition . ▁ ▁Hel io se ism ology ▁ ▁Hel io se ism ology ▁is ▁the ▁study ▁of ▁the ▁wave ▁oscill ations ▁in ▁the ▁Sun . ▁Ch anges ▁in ▁the ▁propag ation ▁of ▁these ▁waves ▁through ▁the ▁Sun ▁reve al ▁inner ▁structures ▁and ▁allow ▁ast ro phys ic ists ▁to ▁develop ▁extremely ▁detailed ▁profiles ▁of ▁the ▁interior ▁conditions ▁of ▁the ▁Sun . ▁In ▁particular , ▁the ▁location ▁of ▁the ▁con ve ction ▁zone ▁in ▁the ▁outer ▁layers ▁of ▁the ▁Sun ▁can ▁be ▁measured , ▁and ▁information ▁about ▁the ▁core ▁of ▁the ▁Sun ▁provides ▁a ▁method , ▁using ▁the ▁SS M , ▁to ▁calculate ▁the ▁age ▁of ▁the ▁Sun , ▁independently ▁of ▁the ▁method ▁of ▁infer ring ▁the ▁age ▁of ▁the ▁Sun ▁from ▁that ▁of ▁the ▁oldest ▁meteor ites . ▁This ▁is ▁another ▁example ▁of ▁how ▁the ▁SS M ▁can ▁be ▁ref ined . ▁ ▁Ne ut r ino ▁production ▁ ▁H ydro gen ▁is ▁f used ▁into ▁hel ium ▁through ▁several ▁different ▁interactions ▁in ▁the ▁Sun . ▁ ▁The ▁vast ▁majority ▁of ▁neut r inos ▁are ▁produced ▁through ▁the ▁pp ▁chain , ▁a ▁process ▁in ▁which