2006/09/11 by J. Bernard-Salas, E. Peeters, G. C. Sloan +3 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Asymptotic giant branch #Emission spectrum #Infrared #Large Magellanic Cloud #Line (geometry) #Nebula #Planetary nebula #Spectral line #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/509777
published as Astrophys.J.652:L29-L32,2006 · 5 pages (in emulateapj), 1 table, 2 figures. Accepted for publication in ApJ Letters
arxiv created 2006/09/11 · openalex publication_date 2006/10/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
We present the first mid-infrared spectra of SMP LMC 11 in the Large Magellanic Cloud. While this object resembles a planetary nebula in the optical, its infrared properties are more similar to an object in transition from the asymptotic giant branch to the planetary nebula phase. A warm dust continuum dominates the infrared spectrum. The peak emission corresponds to a mean dust temperature of 330 K. The spectrum shows overlapping molecular absorption bands from 12 to 17 μm corresponding to acetylene and polyacetylenic chains and benzene. This is the first detection of C 4 H 2 , C 6 H 2 , C 6 H 6 , and other molecules in an extragalactic object. The infrared spectrum of SMP LMC 11 is similar in many ways to that of the preplanetary nebula AFGL 618. The IRS spectrum shows little evidence of nitrogen-based molecules that are commonly seen in Galactic asymptotic giant branch stars. Polycyclic aromatic hydrocarbons are also absent from the spectrum. The detection of the [Ne II] 12.8 μm line in the infrared and other forbidden emission lines in the optical indicates that an ionized region is present.