Transcript: The first systematic survey of active galaxies was carried out by Carl Seyfert in the 1940s. The galaxies he identified, mostly blue mostly spiral galaxies, are named after him. Gas in Seyfert galaxies is highly ionized by an amount that’s too large to be explained by the action of hot stars as in an HII region. There is basically an intense source of ultraviolet photons that cannot be explained by normal stellar processes somewhere in the nucleus. A normal spiral will show broadening of the emission lines based on the rotation of the galaxy, a few hundred kilometers per second in velocity width, but in Seyfert galaxies the width of the broad emission lines is thousands of kilometers per second. Either the gas is being ejected from the nucleus or it’s bound by a large massive object. Either way something unusual is going on in the centers of Seyfert galaxies.