Stellar nodes

Now let us take — 4A = 0, which means that the two roots ate equal ( degeneracy ). This case is similar to the two previous ones. If the two roots ate positive, then the point is called the stable stellar node (attractor) if they ate negative, it is called the unstable stellar node (repeller). 

A plane-parallel stellar atmosphere is a semi-infinite medium. In the numerical calculation, we divide it into n finite elements and 1 semi-infinite element. Let us define a node as a point between two elements. Node 0 is defined as the boundary between the surface element and the vacuum. In total, we have n+1 nodes. The distribution of any physical quantity is represented by a vector of n+1 dimensions with its values at the n+1 nodes as elements. The mean intensity of radiation J is written in the ordinary expression as... 

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