This spectrum looks as if it has a spike on the helium and hydrogen. I have had only one other galaxy with a spike of helium. How common is a helium spike?
by Budgieye moderator
SDSS says that only hot stars have ionized helium. So, 28,000 to 50,000 degrees K
But galaxies are more than stars. There are emissions from black holes, and collisions between clouds of hydrogen. these temperatures can reach millions of degrees.
z= 0.082 0.00001
Three of the big lines, with light blue extending from them, are artifacts, light from our atmosphere. Go to this link and explore sky flux.
Thanks. Its interesting. The only thing I know is what you said, that it has to be really HOT for helium to appear on a spectrum.