Division ring and Quadratic Extension

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First We define involution map which is map

$*$ : $R \rightarrow R$ such that it satisfy

$ i)\ (a+b)^* = a^*+ b^*$ $ii)\ (ab)^* = b^*a^*$ $iii) (a^*)^* = a$

for $a,b$ in $R$.

Now $Z$ be center of ring $R$ now define Involution of first kind over $R$ where $R$ is division ring such that enter image description here

How to describe involution of second kind and what is the automorphism of order 2 here? Also I know that $Z/Z_0$ is galois quadratic extension but why it is quadratic and what is minimal polynomial associated with it? enter image description here