This STIS spectral image shows the velocity distribution of the carbon emission from the gas in the core of NGC 4151. Itrequires more energy to make the carbon gas glow (CIV at 1549 Angstroms) than it does to ionize the oxygen gas seen in the other images. This means we expect that the carbon emitting gas is closer to the heart of the energy source.

Credit: John Hutchings (Dominion Astrophysical Observatory), Bruce Woodgate (GSFC/NASA/ESA), Mary Beth Kaiser (Johns Hopkins University), Steven Kraemer(Catholic University of America), and the STIS Team