Hydrogen-alpha emission

From Memory Alpha, the free Star Trek reference

Hydrogen-alpha emissions are one factor that has to be closely monitored when revitalizing a star.

When Doctor Timicin attempted to revitalize Praxillus, two increases of hydrogen-alpha levels were an early sign that the experiment was going wrong, signalling that neutron migration was taking place during the experiment, which was unexpected, and led to Praxillus going nova. (TNG: "Half a Life")

[edit] Background

The console that La Forge was working on during the experiment on the star is labeled as sensor analysis 4077. This was the M*A*S*H unit that David Ogden Stiers was a member of while he played the character of Charles Winchester on the television series M*A*S*H.