The interstellar 4.62 micron band

Astrophys J. 1999 Mar 1;513(1 Pt 1):294-304. doi: 10.1086/306827.

Abstract

We present new 4.5-5.1 micron (2210-1970 cm-1) spectra of embedded protostars, W33 A, AFGL 961 E, AFGL 2136, NGC 7538 IRS 9, and Mon R2 IRS 2, which contain a broad absorption feature located near 4.62 micron (2165 cm-1), commonly referred to in the literature as the "X-C triple bond N" band. The observed peak positions and widths of the interstellar band agree to within 2.5 cm-1 and 5 cm-1, respectively. The strengths of the interstellar 4.62 micrometers band and the ice absorption features in these spectra are not correlated, which suggests a diversity of environmental conditions for the ices we are observing. We explore several possible carriers of the interstellar band and review possible production pathways through far-ultraviolet photolysis (FUV), ion bombardment of interstellar ice analog mixtures, and acid-base reactions. Good fits to the interstellar spectra are obtained with an organic residue produced through ion bombardment of nitrogen-containing ices or with the OCN- ion produced either through acid-base reactions or FUV photolysis of NH3-containing ices.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Ammonia / analysis
  • Astronomical Phenomena
  • Astronomy*
  • Cosmic Dust / analysis*
  • Cyanates / analysis
  • Extraterrestrial Environment*
  • Hydrocarbons / analysis
  • Ice / analysis*
  • Nitriles / analysis
  • Nitrogen / analysis
  • Photolysis
  • Silanes / analysis
  • Spectrophotometry, Infrared
  • Spectrum Analysis
  • Thiocyanates / analysis
  • Ultraviolet Rays

Substances

  • Cosmic Dust
  • Cyanates
  • Hydrocarbons
  • Ice
  • Nitriles
  • Silanes
  • Thiocyanates
  • Ammonia
  • Nitrogen