Low-ionization nuclear emission-line region

The Sombrero Galaxy (M104) as observed by the Hubble Space Telescope (HST). The Sombrero Galaxy is an example of a LINER galaxy.[1] Credit: HST/NASA/ESA.

A low-ionization nuclear emission-line region (LINER) is a type of galactic nucleus that is defined by its spectral line emission. The spectra typically include line emission from weakly ionized or neutral atoms, such as O, O+, N+, and S+. Conversely, the spectral line emission from strongly ionized atoms, such as O++, Ne++, and He+, is relatively weak.[2] The class of galactic nuclei was first identified by Timothy Heckman in the third of a series of papers on the spectra of galactic nuclei that were published in 1980.[2]

  1. ^ L. C. Ho; A. V. Filippenko; W. L. W. Sargent (1997). "A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". Astrophysical Journal Supplement. 112 (2): 315–390. arXiv:astro-ph/9704107. Bibcode:1997ApJS..112..315H. doi:10.1086/313041. S2CID 17086638.
  2. ^ a b T. M. Heckman (1980). "An optical and radio survey of the nuclei of bright galaxies - Activity in normal galactic nuclei". Astronomy and Astrophysics. 87: 152–164. Bibcode:1980A&A....87..152H.